Phd Abstracts India-Microbiology

DEPARTMENT OF MYCOLOGY & PLANT PATHOLOGY

Ph.D. THESIS ABSTRACTS

1. Name of the student and Admission No.

Kiran Bala Mehta (S-82-A-2-D)

2. Name of Major Advisor Dr. C.L.Jandaik3. Title of Thesis Studies on physiology and cultivation of

Pleurotus sapidus (Schulzer) Kalch.4. Year of completion of Degree 19855. Abstract of Thesis

The sporophores of Pleurotus sapidus were white, moderately fleshy, typically oyster shaped, pileus measuring maximum upto 11 cm diameter. The morphological features closely resembled the type species, P. ostreatus (Jacq. ex. Fr.) Kummer but had a lilac spore print. The physiological studies on P. sapidus revealed that it gives best radial growth on potato-dextrose agar whereas, maximum mycelial weight was recorded in glucose-asparagine solution. The optimum temperature and pH for maximum vegetative growth were found to be 25oC and 5.6, respectively. Both sorbitol and glucose proved to be the best carbon sources while alanine, tyrosine and asparagine, proved best sources of nitrogen. P. sapidus rapidly colonised bajra and Jowar grains, however, maximum yields were obtained with wheat grain spawn and active mycelial spawning. Wheat straw and paddy straw when supplemented with five per cent wheat bran gave the best yield. Good yields were obtained when bags were opened after 25 days of spawning and subsequently kept in the temperature range of 20-25oC with 85-95 per cent relative humidity. The freshly harvested fruit bodies can easily be stored in sealed polythene bags upto 72 hours (maximum) at room temperature (20-30oC) and in freeze (0-5oC) upto 2 months. Moreover, fruit bodies can be dehydrated either mechanically (40-60oC) or in sun. The rehydration ratio was 1:8 approximately. Analysis of different developmental stages of P. sapidus viz., primordia, mature and over mature fruit bodies showed the presence of about 90 per cent moisture. Carbohydrates, fat, protein, fibre and ash were in the range of 51.6-62.0, 0.8-2.0, 14.4-18.2, 13.7-15.6 and 8.3-13.3 per cent, respectively. The mineral analysis revealed that calcium, phosphorus and potassium varied from 0 to 60, 1060 to 1200 and 7533 to 10485 mg/100 g and iron, copper and manganese from 115.5 to 160.5, 27.5 to 43.0 and 39.5 to 43.0 ppm, respectively. The breeding studies by intermating compatible mating types revealed a tetrapolar mechanism of incompatibility.


Gulam Mohamad Dar (S-81-A-3-D)

2. Name of Major Advisor Dr. P.K.Seth3. Title of Thesis Studies on Cladobotryum dendroides (Bull.

per Merat) W. Gam. & Hoozam., causing cobweb disease of Agaricus bisporus (Lange) Sing., and its control

4. Year of completion of Degree 19855. Abstract of Thesis

The mean disease incidence varied between 5.50 to 22.14 per cent. The pathogen was found to attack all the developmental stages of this mushroom. Earliest symptoms of the disease appeared on the mushroom trays infested 12 days after casing. Attacked mushrooms looked like cottony balls. Inoculation 12 days after casing recorded the highest incidence of the disease. The maximum incidence was associated with spent compost casing material. The pathogenic fungus survived in sterilized casing soil for a period of 5 months under laboratory temperatures (10-25oC) whereas, under natural conditions it survived upto 7 months and its virulence decreased with the increase in storage period. Microscopic examination revealed extensive necrosis of the mycelium of Agaricus bisporus. Amongst the solid and liquid media, Sabouraud’s agar and glucose asparagine solution supported maximum growth of the pathogen. A temperature range of 21-24oC and pH range between 6.0-6.4 was found most suitable for the growth of the pathogen. A C:N ratio of 50:1 proved optimum for fungal growth. Thermal sensitivity revealed spores under dry state were capable of surviving 100oC for 15 minutes, whereas, under wet state they survive only 45oC for 15 minutes. Significant reduction of phenol (both total and orthohydric), total sugars, non-reducing sugars, fungal starch, total carbohydrates, proteins (both soluble and crude proteins), fats and free amino acids in varying degrees on account of pathogenesis by C. dendroides. Upon infection the activity of peroxidase decreased rapidly but activity of polyphenol oxidase was augmented at initial infection but decreased significantly at advancement of the disease conditions. The activity of amylase increased significantly with increase in disease development but expression of invertase was more pronounced at initial disease condition as compared to an advance stage of pathogenesis. Themotherapy revealed that the pathogen being killed below the pasteurization temperatures of casing and compost. Bavistin + TMTD at 0.6 and 0.9 g/m2 and TBZ at 0.9 g/m2 treatments proved most effective against cobweb disease and gave yields comparable to the untreated uninfected control.


Kuldeep Kumar Sharma (S-81-A-4-D)

2. Name of Major Advisor Dr. V.K.Gupta3. Title of Thesis Epidemiology and control of powdery mildew

of apple4. Year of completion of Degree 19855. Abstract of Thesis

The maximum disease incidence upto 80 per cent was observed in Mashobra, whereas at Solan it was minimum (20%). At Kullu, Thanedhar, Rajgarh and Kotkhai the incidence was 69, 61, 53 and 42 per cent, respectively. The disease incidence was low in Delicious cultivars whereas cultivars namely Jonathan, McIntosh, Baldwin and Tydeman’s Worcester were highly susceptible. Conidia germinated from 5-30oC with maximum at 20-25oC on apple leaves whereas on slides the germination started at 10oC. On dry glass slides, conidial germination initiated at 96 per cent RH but on apple leaves the germination started at 85.5 per cent RH. No germination was obtained in free water on slides. It did not occur below 98.5 per cent and at 5, 10 and 30oC. Two cultivars namely, Yantarka Altaiskaya and Bagzanka Kaschenco were highly resistant with no apparent infection. The conidia germinated and produced germ tubes on leaves of all the non-host plants (peach, plum, apricot, oak, almond, cherry, pear, Cotoneaster) studied in addition to apple but did not cause any infection in them. These germinated and produced germ tubes of almond equal length on the leaves of both the resistant and susceptible apple cultivars. Each perithecium had a single ascus (36-40.5 x 36-47.5 µm) which in turn, produced 4-8 hyaline ascospores (13.5-18.0 x 13.5-15.75 µm) oval to globose in shape. The ascospores failed to germinate in water. Maximum inhibition of spore germination (78.09%) was obtained with saprol followed by calixin (76.09%). All fungicides completely suppressed sporulation in established lesions for 14 days and Bavistin and Baycor did not allow spore production for 21days in such spots. Amongst the fungicides Baycor (0.05%) provided the most effective control of powdery mildew. Amongst the non-systemic fungicides, Sulfex was significantly superior to Karathane in controlling the disease.


Dhanbir Singh (S-81-A-2-D)

2. Name of Major Advisor Dr. R.K.Agarwala3. Title of Thesis Studies on apple canker caused by Sphaeropsis

malorum Berk. and its control4. Year of completion of Degree 19855. Abstract of Thesis

Temperature ranging between 20-22oC accompanied by high relative humidity (80-90%) during July-August favoured the leaf spot and canker lesions development under field conditions. Maximum canker incidence (92%) was recorded in Kullu valley orchards. The canker incidence decreased with the increase in altitude in Kullu valley. Maximum incidence (38.80%) was recorded on MM 106 followed by Crab apple seedlings (36.19%) and 22.48 per cent on trees with MM 104 rootstock. The canker incidence in scion varieties with M 7 and M 9 rootstock was only 16.66 and 20.00 per cent, respectively. The maximum severity of leaf spot (49.60%) was recorded on Golden Delicious by Red Delicious. Maximum lesion size (38.50 mm) on twig was developed on Tropical Beauty followed by Royal Delicious (36.58 mm). Fruits of ten apple cultivars without exception were found susceptible to the diseases. The conidia remained viable more than 173 days on dead twigs and 117 days in mummified fruits. Potato dextrose agar and Richard’s medium were found as best suited solid and liquid media, respectively for obtaining maximum growth. Only oat meal agar supported the sporulation of the test fungus. The pathogen exhibited optimum growth at temperature 25oC and pH 7.0. The optimum temperature for conidia germination was found as 25oC. The activity of peroxidase was increased in leaves and bark but it decreased in fruits upon infection. No polyphenol oxidase activity was observed in diseased fruits, however, it increased in diseased leaves and bark. Amongst pectinolytic and cellulolytic enzymes, PMG and cellobiase were the most active. Benomyl was adjudged to be the best fungicide in reducing the leaf spot of apple both in pots and the field. Preharvest sprays of thiabendazole and benomyl at 500 ppm were significantly superior in controlling the black rot incidence in storage. Among fungicidal paints tested, cowdung clay paint ranked first in healing the scarified canker wound (83.5%). Preharvest spray of benomyl was highly economical in checking postharvest spoilage of apple.


S.K.Gupta (S-81-A-7-D)

2. Name of Major Advisor Dr. R.K.Agarwala3. Title of Thesis Crop rotation and soil amendment studies in

control of Sclerotinia sclerotiorum (Lib.) de Bary


Cultural practices were found to be very effective in controlling the disease. It was found that the paddy rotated cauliflower plants gave higher yields and also had reduced disease incidence appreciably followed by maize rotation. Significant reduction in sclerotial population was observed in sunflower cake and sarson cake amendments. Among different fungal antagonists tried, Fusarium solani and Aspergillus terreus caused significant reduction in sclerotial population. All the antagonists screened were found effective against the test fungus but the best antagonistic activity was due to F. solani and A. terreus. With the development of the disease, reduction in phenolic content of the stalks was observed. After infection total phenols were decreased in all treatments. Total and reducing sugars increased in all treatments in the healthy mature plants except A. terreus. Toxic metabolites production by antagonistic fungi revealed that all the antagonists inhibited the growth of test pathogen.


Suresh Kumar Nayar (S-81-A-6-D)

2. Name of Major Advisor Dr. R.K.Agarwala3. Title of Thesis Studies on leaf rust resistance in wheat4. Year of completion of Degree 19855. Abstract of Thesis

Six wheat cultivars –C 306, VL 421, WH 322, K 7917, Raj 1972 and HUW 12 were tested at the seedling stage against all the available 19 races of leaf rust (Puccinia recondita tritici) namely, 10 (13R19), 11(0R8), 12 (5R5), 12A (5R13), 12B (1R5), 17 (61R24), 20 (5R27), 63 (0R8-1), 77 (45R31), 77A (109R31), 77A-1 (109R23), 104 (17R23), 104A (21R31), 104B (29R23), 106 (0R9), 107 (45R23), 108 (13R27), 162 (93R7) and 162A (93R15). HUW 12 carry Lr14a; C 306, Lr3 and VL 421, Lr15 + Lr3, whereas Raj 1972, K 7917 and WH 322 have Lr15, Lr1 and Lr10, respectively along with one more Lr gene which could not be postulated on the basis of IT data. The presence of almost all the postulated genes was validated by genetical methods except for Lr3 where either a different gene or modifiers are involved. Lr genes namely Lr2a, Lr10, Lr17 and Lr31 (Lr18) were sensitive to temperature against some specific races.


Chander Dev Thapa (S-80-A-13-D)

2. Name of Major Advisor Dr. C.L.Jandaik3. Title of Thesis Studies on the dry bubble disease of mushroom

(Agaricus brunnescens Peck) caused by Verticillium fungicola (Preuss) Hassebr.


The pathogen could spread through water splash, contact, sciarid flies (adults and larvae), springtails and mites. Beside Agaricus brunnescens, the pathogen could infect A. bitorquis successfully and was able to grow and sporulate on fruit bodies of different Pleurotus species without expressing typical symptoms. Maximum spore germination of Verticillium fungicola was recorded at 25oC and pH 5.5. Spore germination of the pathogen was favoured by extracts of mushroom fruit bodies. The mycelium and spores of V. fungicola when exposed to wet heat (45oC and above) for 10 minutes failed to exhibit growth and germination. Spores and mycelial discs when exposed to different temperatures in dry state, the former could germinate (3%) even after exposure of 90oC whereas the latter could grow only after exposure to 80oC for 10 minutes. The pathogen could survive for 8 months under natural conditions. Best growth of the pathogen was supported by coat meal agar and Richard’s solution. Optimum temperature and pH for the vegetative growth and sporulation of V. fungicola were found to be 25oC and 5.5, respectively. Decrease in both total phenol and orthodihydroxy phenols upon infection as compared to the healthy. There was decrease in total and non-reducing sugars due to infection of V. fungicola. The nitrogen content was less in diseased mushrooms at all the stages except in pinhead stage. The contents of potassium, iron and calcium were more in diseased fruit bodies at all the stages/parts analysed. When various fungicides with different concentrations were amended in the solid medium, the per cent inhibition in growth of V. fungicola was maximum with Bavistin + TMTD. When four sprays were given separately at an interval of fifteen days, the per cent reduction in disease incidence was correspondingly more with four sprays as compared to one spray in all the fungicides used except in case of Benlate, Daconil and Tecto which resulted in less reductions in per cent disease incidence. The loss in yield was minimum with one spray of Benlate and Bavistin + TMTD.


Mohinder Kumar Behl (S-80-A-5-D)

2. Name of Major Advisor Dr. S.C.Chowfla3. Title of Thesis Studies on shoe-string disease of tomato

(Lycopersicon esculentum Mill.)4. Year of completion of Degree 19855. Abstract of Thesis

Characteristic symptoms produced by the virus on tomato included mosaic, vein clearing, downward curling and shoe-stringing of leaves. The virus was found to be easily sap transmissible as well as through aphid vectors. Myzus persicae was the most potent vector followed by Aphis craccivora and A. gossypii. It was not transmitted through seed. Apterous forms of aphid transmitted the virus most efficiently. Optimum pre-acquisition fasting period recorded was 90 minutes, whereas, the acquisition and transmission threshold period were 5 minutes each. The virus had a thermal inactivation point between 55-60oC, dilution end point ranged between 1:10,000 to 1:1,00,000 and longevity in vitro was 4 days at room temperature (28-32oC). Phosphate buffer (0.2 M pH 7.0) was found to be suitable extracting medium. Chloroform plus carbon tetrachloride (1:1) mixture was the best organic solvent for purifying the virus. The antiserum prepared against the virus had a titre of 1:512 to 1:1024 against crude and purified virus preparations, respectively. The virus was found to be serologically related to PVY and under electron microscope it was observed to have flexuous particle with 750 x 11.12 nm size. It was identified as necrotic strain of PVY by virtue of its inducing veinal necrosis on the indicator host i.e. N. tabaccum var. Sasun NN. Out of 115 varieties tested only HC 238 and S-12 were found to be highly resistant. Inoculated resistant line contained more phenols and OD phenols than the inoculated susceptible variety. At initial stages of infection peroxidase activity was more in resistant line, whereas, polyphenol oxidase activity was more in susceptible variety. Virus infection resulted decrease in total, reducing and non-reducing sugar content. During early infection the changes observed in leaf tissues were hypertrophy of epidermal and palisade parenchymatous cells and xylem and phloem vessels. The stem of infected plants showed under developed vascular bundles. Mean air temperature and relative humidity were the main contributing vectors and an average temperature of 22±2oC was found to be most congenial temperature fore the disease development.


Dalip Singh Guleria (S-77-A-11-D)

2. Name of Major Advisor Dr. R.K.Agarwala3. Title of Thesis Studies on Agaricus bitorquis (Quel.) Sacc.4. Year of completion of Degree 19855. Abstract of Thesis

Among different strains studied K 32 and K 26 grew faster than the rest of the strains on synthetic compost. The optimum temperature and pH fore best growth were found to be 30oC and 6.5, respectively for all the strains studied. Out of 12 carbon and 13 nitrogen sources tried, maltose and proline, respectively supported best growth of all the strains. When different carbon : nitrogen (glucose : asparagine) ratios were tried, significantly best vegetative growth of all the strains was recorded with 60:1 ratio. In vitamin nutrition, thiamine was found to enhance significantly best growth of all the strains followed by biotin. Suitability of different spawn substrates to support yield of different strains indicated that spawn prepared on Jowar grains supported maximum yield of all the strains. Maximum yield of mushroom was recorded with through spawning method followed by double layer spawning. When trays were covered with polythene sheet, yield was better as compared to newspaper covering. Compost pH of 7.2 supported maximum yield and decline in pH was much faster in inoculated cased compost as compared to uninoculated. Among different casing materials tried, use of decomposed farm yard manure supported maximum yield of all the strains. When FYM and loam soil were used in combination (1:1 v/v), yield was superior as compared to other combinations of casing materials. Casing depth of 4 cm gave maximum yield of all the strains. A temperature of 28oC followed by 30oC favoured optimum yield of mushrooms. The time required for spawn run was also minimum (10-12 days) with these temperatures. Relative humidity of above 85 per cent and aeration 4-5 hours/24 hours supported maximum yield. Among various pathogens and competitors recorded Verticillium. fungicola, Cladobotryum dendroides and Trichoderma viride were of frequent occurrence. Two sprays of benlate or TBZ resulted in minimum occurrence of T. viride, V. fungicola and C. dendroides.


Gopal Krishan Sood (S-79-A-23-D)

2. Name of Major Advisor Dr. R.K.Agarwala3. Title of Thesis Studies on banded Sclerotial disease (Rhizoctonia

solani f.sp. sasakii) of maize (Zea mays L.)4. Year of completion of Degree 19855. Abstract of Thesis

The disease index was recorded maximum in sub-humid sub-tropical zone followed by sub-humid tropical zone. There was significant reduction in yield in Him-123 and Vijay composite under artificial inoculation conditions were estimated both in the case of cob-yield and grain harvested. The losses sere as high as 70 per cent on 100 grain basis in Him-123 and closely followed by Vijay. The grain yield loss was recorded as high as 93.12 per cent at the maximum disease intensity level in the field. The sclerotia were viable for about two years. The pathogen remained viable in 90 per cent infected seed stored from the previous crop season. Ortho-dihydroxy phenols were increased, whereas, total phenols decreased in leaf and leaf sheath on pathogenesis in Him-123. Polygalacturonase (OG), polymethylgalacturonase (PMG) and pectin transeliminase (PTE) activity was enhanced during pathogenesis. Analysis of diseased and healthy maize leaves for cellulase activity indicated the cellulase activity almost double in leaf tissues on infection. Increase in nitrogen and phosphorus levels increased the disease incidence significantly. Five fungicides viz., Mertect (0.06 %a.i.), Bavistin (0.06% a.i.), Cuman –L (0.10% a.i.), Baycor (0.06% a.i.) and Dithane M-45 (0.20% a.i.) as effective on spray at10 days interval starting on 30 days old crop. Out of 85 germplasm evaluated for their resistance to banded sclerotial disease of maize, 18 were found as resistant.


Rajendra Prasad Kaushal (S-79-A-21-D)

2. Name of Major Advisor Dr. B.M.Singh3. Title of Thesis Genetics of resistance in urdbean (Vigna mungo

(L.) Hepper) to some major diseases occurring in Himachal Pradesh


Forty eight lines/cultivars of urdbean and two accessions of adzukibean were evaluated for resistance to Cercospora canescens, C. cruenta, Colletotrichum truncatum, Erysiphe polygoni and yellow mosaic. Twenty lines of urdbean showed resistance to one or more pathogens. Fourteen urdbean lines, P 7, P 27, P 53, P 103, P 115, P 124, P 127, P 130, P 152, HPU 431, HPU 432, HPU 434, HPU 435 and HPU 502 were resistant to C. truncatum. Twelve lines P 27, P 50, P 53, P 103, P 124, P 127, P 130, P 152, HPU 431, HPU 432, HPU 505 and HPU 25 were resistant to C. cruenta. Only one line P 115 showed resistance to E. polygoni. Two urdbean cultivars Pant U 19 and Pant U 26 were found resistant to yellow mosaic. Nine lines showed resistance to both C. truncatum and C. cruenta and one line was resistant to both E. polygoni and C. truncatum. None of the cultivars/lines of urdbean was found resistant to C. capescens and A. pheseolorum. The adzukibean lines HPU 51and EC 15226 were resistant to isolates of all the pathogens from urdbean. Isolates of C. cruenta from urdbean and adzukibean were host-specific. Isolate of C. truncatum from mungbean was avirulent on urdbean and adzukibean. Isolates of E. polygoni from mungbean and urdbean were virulent on urdbean but avirulent on adzukibean whereas E. polygoni isolate from adzukibean was virulent on urdbean. Isolates of C. canescens from urdbean and mungbean were avirulent on adzukibean. All the isolates of A. phaseolorum were virulent on urdbean but the isolates from urdbean and mungbean were avirulent on adzukibean. Resistance to C. cruenta in the four urdbean lines P 27, P 50, P 53 and P 103 is governed by single recessive genes. Resistance to C. truncatum in P7, P 27, P 103 and P 115 is conditioned by single dominant genes at different loci whereas resistance in P 53 is governed by two complementary genes. Resistance to E. polygoni in P 115 was found to be controlled by a single recessive gene. Resistance to yellow mosaic is cultivars Pant U 19 and Pant U 26 was controlled by single dominant genes at different loci. The study of inheritance of resistance to E. polygoni in adzukibean line EC 15226 showed that it is controlled by cytoplasmic factors and not nuclear genes. Resistance to C. cenescens in the moderately resistant urdbean cultivars HPU 433, Pant U 30 and PDU 2 was quantitatively inherited.


Pranjib Kumar Chakrabarty (S-82-A-3-D)

2. Name of Major Advisor Dr. K.R.Shyam3. Title of Thesis Studies on curd rot of cauliflower4. Year of completion of Degree 19865. Abstract of Thesis

‘A’ type of rot was characterized by soft and malodorous rot of curd tissue, initiated by Fusarium equiseti. ‘B’ type of rot characterized by necrosis, that initiated from the stem of the curd extending upward, was caused either by Sclerotinia sclerotiorum or Pythium aphanidermatum or Pleronospora parasitica. ‘C’ type of rot characterized by the necrosis of the fringes of the curd at the surface forming a brownish black crust, was caused by Alternaria brassicae . ‘D’ type of rot characterized by dry necrosis of the fringes of curd and drying and shrivelling of its smaller stalks was incited by Phoma tropica. The incidence of A type rot was higher than B and C types of rot in all the localities. Temperature, relative humidity and rainfall had a positive correlation with the incidence of A type curd rot, with temperature having the highest correlation coefficient. Incidence of curd rot and curd weight increased progressively with the increase in the level of N, whereas, with the increase of Mg and B through there was an increase in the curd weight yet a considerable decrease in the incidence was observed. Most of the Snowball varieties of cauliflower belonging to FM group exhibited resistance against the disease whereas, the widely cultivated late varieties viz., KAT PSB-1 and Snowball –16 were found to be highly susceptible. All the pathogenic fungi exhibited pectic as well as cellulolytic enzyme activity. Boric acid was found to confer maximum protection to the cauliflower against curd rot. Difolatan amongst the fungicides and bleaching power and Chloramphenicola amongst the antibacterial chemicals were found to provide an effective control of the disease.


Miss Yash (S-82-A-1-D)

2. Name of Major Advisor Dr. R.K.Agarwala3. Title of Thesis Studies on the brown rot of peach caused by

Monilinia species4. Year of completion of Degree 19865. Abstract of Thesis

Out of 18 cultivars of peach screened for resistance against the disease, none was found to be resistant. Peach cultivars Elberta and Tassia Benewas were most susceptible and Sun Red peaches were least susceptible. The fungus was found to infect all stone and pome fruits. Injury provided most vulnerable site for infection to start. The increase in conidial population of the fungus resulted in increased infection. The minimum, optimum and maximum temperatures for the fungus conidia to germinate were 5, 20-25 and 35oC, respectively. The fungus could however, cause infection in peach fruits even at 0oC with an optimum rang of 20-25oC. Both the isolates of the fungus produced polygalacturonase (PG), pectin methyl galacturonase (PMG), polygalacturonate trans-eliminase (PGTE) and pectin methyl trans-eliminase (PMTE) both in cultures as well as in infected peach fruits. The isolate A showed higher enzyme activity than isolate B, establishing the former to be a more virulent isolate. Peach fruits infected with Monilina laxa had higher polyphenol oxidase activity over healthy fruits. Peroxidase activity showed a continuous decline in healthy fruits and a continuous increase in fruits infected with either of the isolates. Total reducing and non-reducing sugar contents, total soluble solids (TSS), acidity and ascorbic acid contents were reduced in peach fruits as a result of infection with M. laxa. Bavistin and thiobendazole at 1000 ppm were found best as tree spray to control brown rot of peach fruits. Similar trend was observed in post-harvest dip treatment with fungicides where Bavistin and Thiobendazole at 500 ppm gave the best control. Fumigation of infected fruits with sodium metabisulphite which released sulphur dioxide fumes was found best among all the fumigants.


Jagdish Kumar (S-82-A-4-D)

2. Name of Major Advisor Dr. G.K.Gupta3. Title of Thesis Studies on the components contributing to

potential ascospore dose of Venturia inaequalis (Cke.) Wint.


Lesion density as determined of 1 m2 leaf area was negatively correlated with the various stages of pseudothecial development i.e. pseudothecial initials, pseudothecia with pseudoparaphyses, pseudothecia with immature wand mature asci. Pseudothecial density not directly linked with lesion density had negative correlation with potential ascospore dose arrived at by measuring the proportion of asci with mature ascospores. Apple cultivar not only affected the pseudothecial density (PD) but also resulted in variable patterns of potential ascospore dose. Cultivars Vance Delicious, Stark Spur Golden and Red Spur Delicious favouring maximum number of pseudothecial initials and pseudothecia with pseudoparaphyses, were the poorest in the production of mature asci and ascospores and reverse was the trend from the leaves of Tydeman’s Worcestor. Quantifying the contribution of each one of these components, it was revealed that only leaf litter density directly influenced PD and potential ascospore dose (PAD), and appropriate would be to minimize the level of leaf litter on the orchard floor by certain means and the inoculum level for delaying the initiation of fungicidal application in spring and keeping apple scab at a low level in the orchard.


Subhash Chand Bhardwaj (S-83-A-16-D)

2. Name of Major Advisor Dr. P.K.Seth3. Title of Thesis Studies on Vert-de-Gris caused by

Myceliophthora lutea Cost. on Agaricus bisporus and its control


Survey of mushroom farms in Himachal Pradesh revealed incidence of 5 to 20 per cent with corresponding losses of 5 to 20 per cent during 1985 and 1986. The pathogen was responsible for the destruction of mycelium, pathogen occurred as circular or uniform colonies through the compost, or mat like seal between compost and casing and only a few clustered mushrooms. Early inoculations with the pathogen resulted in greater losses. Pea stalk compost and FYM recorded good yield despite heavy infestation. Spent compost, air and chicken manure served as sources of the pathogen, spread was through mites, flies and water splashes, favoured by a pH of 7.0 in compost and casing layer. Wet conditions and temperature above 20oC were favourable for spread and increase in duration of storage resulted in loss of viability of the pathogen. Potato dextrose agar and Elliot’s medium were good for solid and liquid medium studies. A temperature of 30oC and a pH of 7.0 with cellulose as carbon, peptone as nitrogen, a C:N ratio of 8.0:0.747, choline chloride (100 ppm) as vitamin source calcium sulphate (5 ppm) as a trace element, ethylene (10 ppm) as a growth regulator source were best suited for the growth of the pathogen. The growth on mushroom extract decreased with maturity and dextrose had maximum impact on growth of the pathogen. Temperature of 30oC and a pH of 7.0 were best for spore germination. Laboratory studies indicated strain numbers 22 and 649 of A. bisporus and K46 of A. bitorquis resistant against pathogen. The pathogen was killed at 51oC for two hours and 60oC for six hours under dry and wet heat, respectively. A decrease in fat, carbohydrate and protein content was recorded in disease compost. The content of amino acids was greatly changed. Decrease in nitrogen, calcium and copper, accumulation of potassium, phosphorous, iron, magnesium, manganese and zinc was common in infected spawned compost. Disease development resulted in decrease in total, OD phenols, increase in ascorbic acid, peroxidase, polyphenol oxidase, cellulase and auxin. Out of the 5 fungicides adjudged effective in laboratory, Benlate (400 and 500 ppm) and Blitox-50 (400 ppm) were found effective against M. lutea and enhanced the yield of A. bisporus when applied to compost or casing soil.


Durga Singh Kaith (S-81-A-1-D)

2. Name of Major Advisor Dr. J.L.Kaul3. Title of Thesis Toximetric studies of systemic fungicides against

Glomerella cingulata (Ston.) Spauld. & Schrenk causing bitter rot of apple


Different systemic fungicides inhibited spore germination of Glomerella cingulata at various concentrations and inhibition ranged from 32.10 to 100 per cent. Bavistin, MBC-50 and Tecto-60 even at the lowest concentration (1 ppm) tried were quite effective. Among non-systemic fungicides, Difolatan resulted in 50 per cent inhibition at 2 ppm. Maximum (41.62 mm) growth inhibition zone (well method) at highest concentration (250 ppm) was produced by Tecto-60 followed closely by Bavistin and Benlate. Preharvest sprayings protected apple fruits effectively upto 90 days at ambient temperature. Bavistin at 750 ppm was most effective followed by MBC-50 and Tecto-60. In Bavistin (750 ppm) treated dip inoculated fruit, rot was observed only after 150 days, whereas with others the rot was recorded after 120 days at ambient temperature. Systemic fungicides proved effective against puncture inoculated fruits (6 h before inoculation) and Bavistin at 750 ppm afforded 85.70 per cent reduction in rotting after 20 days. Postharvest application resulted in persistence of all the fungitoxicants upto 150 days of storage, irrespective of concentration used. Residues ranging from 2.3 to 4.8 ppm in preharvest sprayed fruits were detected 2 days after harvest and there was gradual decline in residues during storage. Treated fruits had higher TSS, acidity, reducing and total sugars and as well as OD phenols. All the test fungitoxicants effectively inhibited the activity of different pectic enzymes. Different fungicides had varying inhibitory effects on cellulases (Cx) activity of both pre and postharvest treated fruits. Peroxidase and polyphenoloxidase activity in treated fruits were significantly least.


Rattan Lal Sharma (S-80-A-14-D)

2. Name of Major Advisor Dr. J.L.Kaul3. Title of Thesis Studies on the brown rot of apple caused by

Monilinia spp.4. Year of completion of Degree 19875. Abstract of Thesis

Studies on the brown rot of apple revealed the prevalence of Monilinia fructigena, M. laxa (Isolate I and II) and M. laxa f. mali in Himachal Pradesh. The cumulative incidence varied from 3.4 to 15.6 per cent. The maximum disease incidence (6.53%) was due to M. fructigena, while the average incidence of 1.67, 0.53 and 0.49 per cent was observed for M. laxa I and II and M. laxa f. mali, respectively. The entry of brown rot fungi through lenticels, stalk and styler end was selective, but a mechanical injury was the potent avenue of their entry. None of the 18 fruit cultivars tested were resistant to these pathogens. Mycelium of the test fungi grew best on potato dextrose agar and glucose asparagine solution and their maximum growth was obtained at 24-25oC. M. fructigena did not sporulate at any of the test temperature (0-35oC), while the other three fungi sporulated at temperatures ranging from 0 to 16oC. The optimum pH for growth was 4.2, sucrose and asparagine proved best carbon and nitrogen source, respectively. Linear growth rate was more in alternate light and darkness. Optimum temperature for spore germination ranged between 20-25oC. Maximum spore germination was obtained on 1 per cent orange juice incorporated with 0.1 per cent sucrose or glucose. Significant reduction of total reducing and non-reducing sugars, total phenols and OD phenols was observed due to the pathogenesis of Monilinia spp. Highest PG, PMG and PME activity was expressed by M. Laxa I and minimum by M. fructigena. The activity of PGTE and PMTE was higher in healthy uninoculated fruits. Cellulase and cellobiase activity was highest due to M. laxa I infection followed by M. laxa f. mali. Amylase and invertase activities were recorded in culture filtrates of the test fungi and variously infected apples as well. Infections of Monilinia spp. in apple caused a fall in polyphenol oxidase, peroxidase, catalase and ascorbic acid oxidase enzymes. Storing apple between 0-5oC was highly effective in controlling brown rot. Dip treatment of apples in water at 50-52oC for 4 minutes was also effective. Four minutes dip treatment in 200 ppm Bavistin at 52oC proved highly efficacious. Apple coated with paraffin oil and caster oil shellec provided significant protection. Sulphur dioxide fumigation was superior over ammonia releasing fumigation in checking the brown rot disease. Preharvest spray with 1000 ppm of the thiabendazole and Bavistin gave significant control. Relative postharvest efficacy of systemic fungicides was more than non-systemics.


Rattan Chand Garg (S-82-A-6-D)

2. Name of Major Advisor Dr. V.K.Gupta3. Title of Thesis Variability and biocontrol of Phytophthora

cactorum on apple4. Year of completion of Degree 19875. Abstract of Thesis

Four isolates of Phytophthora cactorum were found to be pathogenic on apple rootstocks, cultivars and different plant species. P4 isolate was most virulent amongst the four followed by P3, PL2 and P1. Amongst 25 apple rootstocks tested, MM102 was most resistant. MM106 was less susceptible to P3, MM105 to P1 and P2 and M3 to P1 isolate. M16 rootstock was found to be the most susceptible to all the fungal isolates. Amongst 15 apple cultivars, McIntosh was most susceptible and Red Delicious had least susceptibility. Amongst nine plant species tested, apricot was found to be most susceptible and almond was highly resistant. Amongst different seasons, highest degree of susceptibility in apple rootstocks was noticed during bud swell stage followed by summer and least during the month of September. P4 fungal isolate grew more profusely in culture media but P1 was found to have minimum growth. Healthy susceptible rootstocks (M16 and MM104) had higher amounts of total phenols as compared to resistant ones (MM102 and M26), but in case of OD phenols, reverse trend was noticed. The reduction was more in susceptible rootstocks in comparison to resistant ones. Virulent strains of the fungus caused less increase in OD phenols as compared to less virulent isolates. Healthy susceptible rootstocks had less activity of polyphenol oxidase than resistant ones. The activity increased in all the rootstocks after infection. Peroxidase activity increased after infection in all the rootstocks and susceptible rootstocks had less activity of this enzyme as compared to healthy resistant ones. Amongst bacterial antagonists, Bacillus subtilis (B1) was found to be most effective and it was followed by Enterobacter aerogenes (E). Amongst the fungi, Trichoderma viride (T1) was most effective antagonist.


Vijay Singh Thakur (S-83-A-17-D)

2. Name of Major Advisor Dr. G.K.Gupta3. Title of Thesis Studies on the effect of fungicides on apple scab

(Venturia inaequalis (Cke.) Wint.) pathogenesis4. Year of completion of Degree 19875. Abstract of Thesis

Ergasterol-biosynthesis-inhibiting (EBI) fungicides namely fenarimol (48 µg a.i./ml), prochloraz (297 µg/ml) and bitertanol (250 µg/ml) had longer protective activity for upto 120 hr pre-inoculation. Persistence (retention) of dodine (487.5 µg/ml), mancozeb (1875 µg/ml), dithianon (562.5 µg/ml), carbendazim (375 µg/ml), myclobutanil (45 µg/ml) and bitertanol (187.5 µg/ml) under the impact of 5 cm rainfall was better for effective control of apple scab. The curative activity of EBI and benzimidazole fungicides was confirmed to 72 hr and of benzimidazoles and dodine 48 to 72 hr after inoculation and beyond this interval, their activity was not static. All eight EBI fungicides (bitertanol, etaconazole, myclobutanil, penconazole + captan, PP 523, prochloraz, fenarimol and triforine) shared with carbendazim, thiophanate methyl, dodine and guzatine a high level of pre-symptom activity whereby lesions developed on the leaves were atypical and were either chlorotic or in the form of reddish brown flecks. Ultrastructure studies of subcuticular hyphae of the pathogen with the aid of electron microscope confirmed the reliability of isolation procedure and showed that in myclobutanil induced reddish brown flecks, fungal hyphae had become necrotic with disintegration of various cell organelles. When applied on established scab lesions, myclobutanil (30, 45 and 60 µg/ml) provided maximum reduction in spore numbers and spore germination. Based on the activities of fungicides as studied and utilization of predicted infection periods with the help of Biomat SWG Apple Scab Predictor and deWit Leaf Wetness meter in timing the fungicide application, two different spray programmes (curative versus protectant) were developed and tried in the orchard with high levels of inoculum.


Gulam Muhammad Beig (S-83-A-13-D)

2. Name of Major Advisor Dr. C.L.Jandaik3. Title of Thesis Studies on Pleurotus cystidiosus Miller4. Year of completion of Degree 19875. Abstract of Thesis

The species is characterized by its ceremioid imperfect stage, Antromycopsis brousonetiae Pat. and Traub. The fast linear growth was supported by yeastal PDA whereas maximum dry mycelial weight was recorded on glucose-asparagine solution. Optimum temperature and pH for the vegetative growth were found to be 28±1oC and 6.0, respectively. Among twenty carbon sources tried, dextrose and dulcitol proved to be the best whereas proline and asparagine were the best nitrogen sources. Inssitol (50 ppm), copper/zinc (5 ppm) and gibberellic acid (0.5 ppm) favoured maximum growth of P. cystidiosus. Among several spawn substrates tested, jowar grains favoured the fast linear growth, however, maximum yield and biological efficiency were supported by wheat grain spawn. Temperature range of 26-28oC, relative humidity of above 85 per cent, 2 hour aeration ad 1 hour photoperiod per 24 hours, proved to be optimum for improved substrate colonization, primordia formation and development of fruit bodies as well as yields. The total crude protein content varied from 26.87 per cent in primordia to 37.06 per cent in mature sporophores. The fungal pathogen/competitors observed during the cultivation experimentation were Oedacephalus glomerulosum, G. lineatus, Gliocladium deliquescens and Sibirina fungicola among the pathogens while the competitors were Trichoderma viride, Styasnus medius and Sordaria fimicola. The freshly harvested fruit bodies could easily be stored in sealed polythene bags upto 48 hours at 20-25oC and in refrigerator (0-5oC) upto 18 days.


Narendra Kumar Taneja (S-82-A-5-D)

2. Name of Major Advisor Dr. P.K.Seth3. Title of Thesis Studies on Myrothecium leaf spot disease of

cotton4. Year of completion of Degree 19885. Abstract of Thesis

Seventeen isolates of Myrothecium roridum were obtained from different varieties belonging to Gossypium and Vigna species collected from 4 different locations. Growth studies revealed that the maximum vegetative growth and sporulation of M. roridum were supported by Richard’s and potato dextrose media. M.roridum was found to enter through stomatae or directly piercing the epidermis of cotton leaves. The maximum disease development took place on the plants upto the age of 28 days, however, the disease could develop well upto the plant age of 56 days. Cultural, physiological and pathogenic variability among the 17 isolates of M. roridum were studied. According to pathogenic ability on 15 varieties of Gossypium species and two varieties of Vigna species, the 17 isolates could differentiated into 5 pathotypes. Analysis of free amino acids in resistant and susceptible varieties revealed the presence of 7 amino acids (alanine, arginine, asparagine, glutamine, histidine, H-prolines and tyrosine) in the susceptible varieties whereas these were absent in resistant varieties. Two amino acids (leucine and tyrptophan) were present only in resistant varieties which may be responsible in providing resistance. Screening of 506 germplasm lines belonging to all the cultivated species of Gossypium and M. roridum under glasshouse conditions, showed that only 10 lines viz., Arkansas green, GP197, Kirghis K2, Line F (Hyb. 330), M-DH-66, Mex 685-6, Pee Dee 113, Pee Dee 259, Pee Dee 875 and SRIF4 were resistant. Bavistin, Blitox-50 and Delsan were effective in controlling the disease.

1. Name of the student and

Admission No.Jagan Nath Sharma (S-83-A-14-D)

2. Name of Major Advisor Dr. J.L.Kaul3. Title of Thesis Structural and biochemical nature of resistance in

apple to Venturia inaequalis (Cke.) Wint. causing scab


Various morphological and biochemical studies were conducted for ascertaining their correlation with scab in known resistant and susceptible cultivars of apple. In 1986 season, scab appeared in first week of April in Kullu valley on all the test cultivars. Prima, Priscilla and Liberty possessed minimum number of scab lesions (all non-sporulating) per extension shoot and were rated as resistant; Royal Delicious, Red Delicious and Golden Delicious were moderately susceptible; and McIntosh, Granny Smith and Coatland were highly susceptible with minimum latent period of 11 days. As for as morphological characters were concerned, there was no bearing of any of the character like extension shoot growth, leaf area, stomatal number, stomatal per size and thickness of bark or bark/wood ratio whatsoever on the resistance or susceptibility of these cultivars. Cultivar also showed variation in the thickness of cuticle, epidermis and cell wall but showed no relationship with disease resistance either. An upsurge in total and OD phenols was observed in leaves after 10 days of inoculation, the increase being more conspicuous in he resistant cultivars. Both phloridzin and its aglucone phloretin were assayed from the test cultivars and the level of phloredzin was correlated with scab resistance in the young expanding leaves. Higher total soluble sugars were associated with increased susceptibility to scab and sorbitol dominated only in the resistant cultivars. Higher content of malic acid and tartaric acid seemed to be associated with the resistant behaviour of test cultivars. Higher soluble protein count in the inoculated older leaves showed significant correlation with the increased susceptibility. Free aminoacid pool depleted with aging and pathogenesis. In healthy leaves of resistant cultivars, DL-phenyl alamine dominated and L-histidine was exclusively present in these cultivars. Also high potassium and calcium contents were associated with the resistance. Comparatively higher enzymatic activity of peroxidase, catalase and B-glucosidase was assayed in uninoculated younger leaves of the test cultivars and that of B-glucosidase was particularly correlated with scab resistance in apple.


Bishnu Prasad Baruah (S-83-A-12-D)

2. Name of Major Advisor Dr. S.C.Chowfla3. Title of Thesis Studies on a mosaic disease of cauliflower

(Brassica oleracea L. var. botrytis)4. Year of completion of Degree 19885. Abstract of Thesis

The virus was sap transmissible as well as through aphid vectors. Brevicoryne brassicae was the most efficient vector. Optimum pre-acquisition fasting period was 60 minutes whereas, acquisition access period and inoculation access period of 5 minutes each resulted in maximum transmission. Virus infected plants of cruciferae, solanaceae, compositae, leguminosae and chenopodiaceae. The virus was TIP 55-60oC, DEP 1:103 to 1:104 and LIV was 72 hours. Virus particles were long flexuous rods measuring 720-750 x 12 nm. Virus induced cylindrical cytoplasmic inclusions, Based on morphology and serology, the virus was identified as turnip mosaic virus-ordinary strain. The disease spread was influenced greatly by air temperature and vector population. Out of 47 cauliflower varieties/virus infection increased the dry matter and decreased moisture content, chlorophyll and carbohydrates.


Jagdish Chander Kaushik (S-84-A-17-D)

2. Name of Major Advisor Dr. V.K.Gupta3. Title of Thesis Studies on seedling diseases of Eucalypts4. Year of completion of Degree 19885. Abstract of Thesis

A total of nine fungi namely, Cylindrocladium quinqueseptatum, C. clavatum, Fusarium solani, F. equiseti, F. moniliforme, Rhizoctonia solani, Aspergillus sp. and Rhizopus sp. were found to be associated with root/collar region of eucalypts seedlings having root and collar symptoms. In addition to both the species of Cylindrocladium, Pestalotiopsis disseminata, Alternaria alternata and Curvularia sp. were also isolated from leaves showing blight. C. quinqueseptatum and Alternaria alternata were prevalent in all the nurseries surveyed in the state whereas fungi like Fusarium sp., C. clavatum and S. rolfsii were more prevalent in foot hill areas. Maximum damping-off incidence was evident in 25 days old, seedlings which reduced drastically in 90 days old ones. Clay soil was found to have maximum disease and even soil mixture having more clay content had increased disease intensity. Seedling mortality was maximum in 100 per cent soil moisture at 25oC temperature. N deficiency decreased disease whereas that of P, K and Ca, Mg and Zn increased it. Benlate, Bavistin, Captan and Difolatan were found to decrease damping-off of eucalypts seedlings effectively when used as seed treatment. In case of pre and post-inoculation drench in soil, Benlate was most effective followed by Bavistin, Difolatan, Captan and Thiram as promising fungicides. Similarly, for leaf and shoot blights, all the five fungicides as mentioned above were found to be most effective. Soil amendments with cotton cakes, maize straw and saw dust reduced seedling mortality. Sowing of seeds on raised seed beds was better than sowing on sunken beds. Similarly, sowing of seeds upto 0.5 cm depth in soil gave maximum final plant stand which reduced considerably at 2.5 cm depth. Under green house conditions, B.subtilis, T. harzianum and T. viride were found to be most promising in controlling damping-off of eucalypts seedlings.


Sudheer Kumar Rana (S-85-A-13-D)

2. Name of Major Advisor Dr. V.K.Gupta3. Title of Thesis Studies on root rot of Populus species4. Year of completion of Degree 19895. Abstract of Thesis

Dematophotra necatrix produced symptoms like bronzing or premature yellowing of leaves, defoliation, stunting growth, and death of the shoots. The infected roots showed white clusters of the fungus mycelium attached to soil around roots and greyish mycelium strands on root surface. Soil moisture and temperature had strong relationship and disease incidence was maximum at 22oC and 75 per cent moisture level. A soil pH of 6.5 was found to be most suitable for maximum development of root rot. The variability studies revealed that D. necatrix isolates from poplar (three isolates) and apple were the same. The toxic metabolite of D. necatrix in culture filtrate was toxic to the leaves, shoots and plants of fourteen Populus species. Soil amendments with neem cake gave good control of disease under pot as well as field conditions. Trichoderma viride followed by T. hamatum and Enterobacter aerogenes gave good control of poplar root rot (D. necatrix). Bavistin followed by Benlate, TBZ, Topsin-M, Dithane M-45 and Difolatan were found to reduce the incidence of poplar root rot under pot as well as field conditions. Amongst Populus species and hybrids tested by following different methods, P. euramericana ‘I-65’, P. euramericana ‘I-154’, P. ‘Gwydr’, P. ‘Reinbek’ and P. rubra-poiret were resistant to D. necatrix.


Pankaj Kumar Gupta (S-85-A-11-D)

2. Name of Major Advisor Dr. K.R.Shyam3. Title of Thesis Epidemiology and management of fungal

nematode rhizome rot complex of ginger4. Year of completion of Degree 19895. Abstract of Thesis

The survey studies revealed the association of six fungi, namely, Pythium aphanidermatum, Fusarium equiseti, F. solani, Cladosporium cladosporioides, Mucor hiemalis and Aspergillus niger and a nematode species Meloidogyne incognita. Among these, three fungi namely P. aphanidermatum, F. equiseti and F. solani and the nematode M. incognita were found to be pathogenic. Interaction studies revealed that F. equiseti and F. solani when inoculated four weeks after nematode inoculation proved more deleterious to ginger growth. In case of P. aphanidermatum, however, the maximum reductions in shoot, root and rhizome weight were observed when the fungus and nematode were inoculated simultaneously. An average soil temperature of 25oC coupled with 75 per cent soil moisture level caused maximum disease incidence in case of P. aphanidermatum and F. solani. Whereas maximum disease incidence in case of F. equiseti was obtained when 100 per cent soil moisture was combined with 25oC temperature. In case of nematode, however, the maximum number of galls was produced at 30oC with 75 per cent soil moisture level. Neem fruit cake was the most effective in reducing disease incidence caused by each pathogen alone as well as when all the four pathogens were present together. The second best amendment material was sarson cake. Aliette, Ridomil MZ (both at 0.15% conc.), Difolatan, Galebn (green) and Dithane M-45 (all at 0.30% conc.) proved highly effective in controlling the rhizome rot complex.


Ved Parkash Sharma (H-86-11-D)

2. Name of Major Advisor Dr. C.L.Jandaik3. Title of Thesis Recycling of wastes from mushroom cultivation

for growing some edible fungi4. Year of completion of Degree 19895. Abstract of Thesis

A combination of wheat straw and spent straw in ratio of 25:75 recorded yields at par with 50:50 combination in case of all the edible fungi except Pleurotus sapidus, P. florida and Agrocybe aegerita. Supplementation of wheat straw plus spent straw (50:50) with wheat bran and brewer’s grain (both 5%) produced enhanced yields as compared to yields recorded on wheat straw alone in case of all the fungi studied. Supplementation of the substrate prior to pasteurization was found to be better than the supplementation done after pasteurization. Supplementation of spent compost with wheat bran (5%) resulted in maximum increase in all the cases except Auricularia polytricha. Supplementation of Pleurotus waste plus wheat straw (50:50) with apple pomace (20%) during composting supported yield of A. bisporus. Among different spawn substrate evaluated, jowar grains supplemented with gram powder 5 per cent favoured maximum yield of all the fungi followed by jowar grains. P. sapidus fruit bodies produced on wheat straw contain maximum (15.8%) amount of fibbers. In case of carbohydrates, the maximum (70.5%) amount was detected in P. ostreatus produced on wheat straw alone and spent straw or spent compost. A new pathogen Cladobotryum verticillatum (Link ex S.F. Gray) Huges was recorded infecting fruit bodies of Pleurotus species and Auricularia polytricha.


Balam Chand Suman (H-85-9-D)

2. Name of Major Advisor Dr. C.L.Jandaik3. Title of Thesis Management of competitors of spawn of

Agaricus bisporus (Lange) Sing. 4. Year of completion of Degree 19895. Abstract of Thesis

Per cent frequency of different micro-organisms varied from month to month and fungi were the largest group of micro-organisms. Aspergillus niger contributed towards highest spoilage followed by Penicillium species. Boiling of wheat grains for 15 or 20 minutes resulted significantly in maximum linear growth and minimum incubation period (colonization and spawn substrates). Calcium carbonate and calcium sulphate in 30: 120 combination (1:4 ratio w/w) on wet weight basis of grains supported highest mycelial growth and took minimum duration for colonization of spawn substrate. There was no contamination if sterilization was done at 1.54 kg/cm2 for 120 minutes, irrespective of number of bags. If contaminated bags are sorted out well in time, resterilization at 1.54 kg/cm2 for 2 hrs was found quite effective. Fresh spawn produced significantly maximum linear growth in all types of cultures as compared to spawn stored for different intervals. Liquid nitrogen storage (-160 to –196oC) of spawn of one year did not effect either the yield or average stipe length as well as pileus diameter as compared to fresh spawn. With the increase in storage temperature (2 to 6oC) and period (6 to 24 months), there was significantly corresponding decrease in the yield. Month-wise evaluation of A. bisporus spawn stored at different temperature (2 to 6oC) indicated that storage beyond one month period resulted in reduced yield as compared to fresh spawn. Multispore culture spawn was found to be more productive followed by tissue culture and single spore culture spawn.


Sunita Sen (H-87-6-D)

2. Name of Major Advisor Dr. V.K.Gupta3. Title of Thesis Management of soil borne diseases in Robinia

pseudoacacia Linn. nurseries4. Year of completion of Degree 19905. Abstract of Thesis

During the survey of Robinia nurseries, located in four different districts of Himachal Pradesh, a total of 12 fungi namely, Allescheriella sp., Armillaria sp., Botrytis (Sclerotinia minor), Fusarium equiseti, F. solani, F. semitectum, F. oxysporum, Penicillium spp., Rhizopus nigricans, R. oryzae, Trichoderma spp. and Verticillium sp. were isolated from the diseased roots and rhizosphere. The wilt disease was present in all the areas surveyed. Amongst the fungi isolated, F. oxysporum was most virulent followed by F. semitectum, F. equiseti and F. solani. These species were associated with symptoms like damping-off, rotting and wilt. F. oxysporum was more virulent than the other two Fusarium species. Black colour seeds were more resistant to infection than grey and brown. Meloidogyne incognita, the root knot nematode enhanced the infection in case of F. oxysporum and F. equiseti. Soil amendments with cotton cake gave reduction of wilt caused by F. oxysporum. White radish, carrot and gram crops before Robinia proved helpful in reducing wilt caused by all the Fusasrium species. Under pot conditions, maximum reduction in disease was achieved by B. subtilis agaisnt F. equiseti and F. semitectum followed by T. viride.


Piar Singh Andotra (H-86-10-D)

2. Name of Major Advisor Dr. S.C.Chowfla3. Title of Thesis Studies on virus diseases of cucumber (Cucumis

sativis L.) in Himachal Pradesh4. Year of completion of Degree 19905. Abstract of Thesis

Investigations were conducted to identify different viruses/strains responsible for cucumber mosaic disease in cucumber. Incidence of 0.00 to 46.6 per cent of mosaic disease in cucumber was recorded during surveys of different districts of HP. Symptoms as chlorotic spots on cotyledons, yellows mosaic patterns, vein clearing, vein banding, puckering and wrinkling of leaves, and stunting of plants were evolved in mosaic disease by various virus isolates. All the isolates were sap and aphid vector transmitted except CM-5, which was not transmissible by any aphid vectors. The TIP, DEP and LIV of the isolates ranged between 55-70oC, 10-2, 10-4, 12 hours to 5 days at room temperature and 5-17days at refrigeration, respectively. Virus isolates CM-1, CM-3, CM-4, CM-6 and CM-7 contained isometric particles ( 30 nm in diameter), whereas isolate CM-2 had long flexuous rod shaped particles measuring 750x11 nm seen under electron microscope. Based on different identification parameters, the virus isolates were identified as possible member of cucumovirus (CM-1, CM-3, CM-4, CM-6 and CM-7), potyvirus (CM-2) and nepovirus (CM-5) groups. In epidemiological studies, mean air temperature and vector population influence cucumber mosaic disease incidence to grater extent. Early sowing, use of yellow polythene mulch and spray of Karate were found effective in reducing disease incidence. Out of fifty seven germplasm collections against cucumber mosaic virus(es), none were found resistant under field conditions.


Harinder Paul Singh Sahi (H-97-14-D)

2. Name of Major Advisor Dr. K.R.Shyam3. Title of Thesis Epidemiology and management of Alternaria leaf

spots of tomato in Himachal Pradesh4. Year of completion of Degree 19905. Abstract of Thesis

Alternaria alternata f.sp. lycopersici was invariably found to be associated on lesions produced on leaflets, stems and branches whereas A. alternata was associated only with lesions produced on leaflets. At 25oC, A. alternata f.sp. lycopersici was found to be more pathogenic than A. alternata. The growth of both the pathogens were favoured by water agar + leaflet bits and temperatures of 20 and 25oC were found to be optimal for the growth of A. alternata and A. alternata f.sp. lycopersici, respectively. Per cent severity index of leaf spots caused by A. alternata f.sp. lycopersici at all locations upto 90 days of transplanting, after which the reverse was true. Early transplanting of crop, resulted in delayed appearance of leaf spots caused by both the pathogens. Among the various lines/cultivars screened, four germplasm lines viz., EC-174069, EC-174025, EC-174057 and a cultivar Marglobe were found resistant to both the pathogens under natural epiphytotic conditions. Clipping of lower leaves upto 20 cm height from the ground level resulted in increased yield and decreased leaf spots severity caused by both the pathogens in weeded as well as unweeded plots. Application of Hexacap proved most effective in reducing the leaf spots severity of both the pathogens during the years 1988 and 1989. Combination of Hexacap sprays with clipping of lower leaves (20 cm from the ground level) and weeding exhibited the additive effect on the decreased the severity of leaf spots caused by both the pathogens. Similarly, Bordeaux mixture application coupled with clipping of lower leaves (20 cm from the ground level) and weeding also recorded the highest fruit yield among all the treatments tried.


Dharam Singh Dodan (S-87-1-D)

2. Name of Major Advisor Dr. K.R.Shyam3. Title of Thesis Variability in Phytophthora nicotianae var.

parasitica (Dast.) Waterhouse and management of buckeye rot of tomato in Himachal Pradesh


In all, 26 isolates obtained from diseased specimens, collected from different locations were chosen. The maximum average number of sporangia (84.8) was found formed on OMA closely followed by CMA with 0.01M KNo3 solution and rain water as vapour condensation substrates. Oospores were observed only in old cultures after 90 days of incubation at 25oC. However, no oospore production was observed in diseased seedlings. The mass isolates varied considerably from each other on the basis of their growth preferences to different solid media. A temperature ranging from 25-30oC and pH from 5.0 to 6.0 were found optimum for the growth of the mass isolates. The mass isolates of the pathogen exhibited considerable variation in growth with different concentrations of the thiamine. There was an increase in sporangial germination with increase in temperature from 20 to 30oC and maximum sporangial germination was recorded at 30oC. The age of the fruit had no effect on disease development. Considerable variation in the aggressiveness of mass isolates f the fungus was observed on different hosts. Among the various cultivars and lines screened, only one line i.e. Ceresiformae was found resistant. Combination of fungicide sprays with clipping of lower leaves (15 cm from the ground level), mulching with polythene and weeding exhibited in additive effect on the reduction of buckeye rot incidence.


Kishore Kumar (H-87-2-D)

2. Name of Major Advisor Dr. G.K.Gupta3. Title of Thesis Influence of bio-meteorological parameters in

apple scab development and its management4. Year of completion of Degree 19915. Abstract of Thesis

Studying the development of scab fungus in relation to weather conditions, moisture either in the form of dew or rain had greater impact in initial development of pseudothecia within 30-35 days after leaf fall. Temperature had a negative effect on the number of pseudothecia per unit leaf area and number of asci per pseudothecium whereas rainfall was positively correlated. Maximum ascospore productivity coincided with the full bloom in 1989 and with the petal fall stage in 1990. Pseudothecia were fully exhausted at 2 cm and 2.5 cm fruit diameter stage in 1989 and 1990, respectively. When ascospore emission period was correlated with degree days (oC), accumulation of 930oC and 976.55oD was necessary for total emission of ascospsores in 1989 and 1990, respectively. This showed that on an average, ascospore emission period was of 62-68 days at an average of 953oC. Ascertaining the validity of Mills’s criteria, it was revealed that days required for symptom expression were more than predicted by Mills. Curative activity of ergosterol-biosynthesis inhibiting (EBI) fungicides namely flutriafol, hexaconazole, myclobutanil and fenarimol was confined to 72 hr. However, these fungicides provided good control when applied 120 hr after initiation of predictive infection period in the orchard. The post-symptom anti-sporulant activity of flutriafol was excellent and was superior to all other EBI fungicides tested. Second best fungicide for reduction of conidial production was fenarimol. Myclobutanil was second best to flutriafol in inhibiting the spore germination.


Rajeev Raina (H-87-4-D)

2. Name of Major Advisor Dr. C.L.Jandaik3. Title of Thesis Studies on bacterial blotch of Agaricus bisporus

(Lange) Sing. and its management4. Year of completion of Degree 19925. Abstract of Thesis

The organism responsible for blotch was identified as Pseudomonas tolaasii. Epidemiological studies revealed that temperature and relative humidity collectively contributed for less than 50 per cent of the disease development. Blotch bacterium could induce symptoms on Agaricus bitorquis and resulted in rotting of Pleurotus sajor-caju while A. polytricha and A. aegerita was found to be 55 and 66oC in aqueous and moist soil, respectively. When temperature was kept constant (16±1oC), there was increase in per cent diseased mushrooms with increase in relative humidity. In vitro evaluation of different antibiotics, revealed that oxytetracycline and streptocycline were found to be quite effective as compared to others when evaluated by different techniques. Neem cake and garlic clove extracts were found to be quite effective in inhibiting the blotch pathogen. Under mushroom house conditions, two sprays of oxytetracycline (400 ppm) resulted in minimum number of diseased fruit bodies. The mushroom yield recorded in different treatments did not differ significantly among themselves, indicating that blotch disease did not effect yield of mushrooms harvested.


Sandeep Kansal (H-88-11-D)

2. Name of Major Advisor Dr. J.L.Kaul3. Title of Thesis Studies on Sclerotiorum root rot of yellow horned

poppy4. Year of completion of Degree 19935. Abstract of Thesis

Root rot of yellow horned poppy (Glaucium flavum Crantz.) caused by Sclerotium rolfsii Sacc. was found in severe form during the rainy seasons (1990-1991) at two localities in Solan district of Himachal Pradesh. Severe yellowing and wilting were the first symptoms followed by shrivelling and drying of the foliage. The pathogen invaded the collar portion of the plant more readily than other plant portions. The susceptibility decreased with plant age increasing from 3 to 11weeks. Under green house conditions, the edaphic factors like soil moisture (60% MHC), soil pH (6.0-7.0), presence of host leaf substrate and close proximity (1 cm) of dried sclerotia favoured the root rot development. The meteorological factors, namely soil moisture (27.2 – 30.5%), soil temperature (25.3 – 30.5oC) had a positive correlation with the disease progression under natural conditions. The survival of sclerotia was adversely affected at moisture levels more than 50 per cent, temperature ranging from 25 to 30oC, depths deeper than 60 cm. The temperature range of 30 to 35oC, pH 6.0 and solute water potential of –1.0 bar were optimum for sclerotial germination. The prolonged exposure (14 h) to UV light and burial of sclerotia at deeper depths more than 60 mm significantly reduced the germinability. High enzyme (pectic, celulolytic) and oxalic acid activities were recorded both under in vitro and in vivo conditions. The root rot caused a significant loss in glaucine content of the host plant. None of the twelve yellow horned poppy test lines showed resistance to the pathogen. Soil solarization treatment of four weeks was efficacious in limiting the root rot. The cultural practices like deep ploughing and no-lay-by operation provided effective disease remission when used in combination with fungicide (Vitavax @ 0.15% or Captaf @ 0.25%) and fertilizer (ammonium bicarbonate @ 84 kg N/ha). Soil amendments with oat straw, castor, neem cake (1.0 % w/w) and calcium ammonium nitrate (60 kg N/ha) provided promising control. Vitavax (2000 ppm) was efficacious fungicide in inhibiting the mycelial growth of S. rolfsii. Soil drenching with Vitavax (0.15%), Calixin (0.05%), Captaf (0.25%) and Thiram (0.20%) were highly effective in suppressing the root rot expression. G. virens, T. harzianum and T. viride in conjunction with calcium ammonium nitrate (40 kg N/ha) were highly efficacious against the disease under pot culture.


Amar Nath Chandrani (S-89-10-D)

2. Name of Major Advisor Dr. J.L.Kaul3. Title of Thesis Studies on postharvest diseases of peach and their

management4. Year of completion of Degree 19935. Abstract of Thesis

Four diseases namely whisker’s rot (Rhizopus stoloifer), brown rot (Monilinia laxa), black mould rot (Aspergillus niger) and blue mould rot (Penicillium expansum) predominated causing 87 per cent of the total fungal spoilage. Whisker’s rot was most destructive of all the rots. The average cumulative fruit loss was 23.64 per cent. Spores of M. laxa could germinate at 5oC, but the spores of other test pathogen did not. The optimum temperature range for spore germination of M. laxa 20-25oC, and A. niger 27-30oC whereas for P. expansum and R. stolonifer, it ranged between 24 to 27oC. P. expansum expressed highest polygalacturonase (PG) activity in in vitro followed by M. laxa. M. laxa exhibited highest polymethylgalacturonase (PMG) activity under both the conditions followed by P. expansum, R. stolonifer and A. niger in descending order of significance. The in vitro PG and PMG activities were lower than in in vivo. P. expansum possessed highest pectinmethylestrase (PME) activity in in vivo and M. laxa under in vitro. The cellulase (Cx) activity was highest in R. stolonifer, followed by P. expansum under in vivo and in vitro conditions. Various fungal infections resulted in sharp decline in polyphenol oxidase (PPO) activity, excepting M. laxa infection, which resulted in increased activity. Immediate hydrocooling after inoculation significantly retarded M. laxa development in peaches placed at 25oC, in comparison to 24 and 36 h delayed cooling. Hydrocooling of R. stolonifer inoculated peaches, immediately and holding them at 25oC did not affect the rot development. After 24 h delay, hydrocooling of inoculated peaches with Botran (300 ppm) significantly reduced the R. stolonifer decay. Treating peaches in water at 52oC for 4 min significantly effected the development of various fungal decays. DCNA (Botran) wrappers were quite effective against whisker’s rot and also inhibited the brown rot. Iodine potassium iodide (IPI) wrappers were almost equally effective against blue and black mould rots. Fumigation of variously inoculated peaches with potassium and sodium metabisulphite was highly efficacious against blue mould and brown rot, respectively. Preharvest sprays with 1500 ppm Bavistin and Topsin-M gave significant control of brown and blue mould rot. Botran sprays at 2000 ppm were efficacious against Rhizopus rot.


Rakesh Kumar Mandradia (H-89-12-D)

2. Name of Major Advisor Dr. K.R.Shyam3. Title of Thesis Studies on soft rot of cauliflower seed crop in

Himachal Pradesh4. Year of completion of Degree 19935. Abstract of Thesis

The plant mortality due to soft rot ranged from 0.5 to 70.0 per cent and the corresponding loss in seed yield ranged from 2.0 to 280.0 kg per hectare at different locations. In all 6 fungi, viz., Alternaria brassicae, Aspergillus flavus, Fusarium equiseti, Pythium aphanidermatum, Rhizopus stolonifer and Sclerotinia sclerotiorum and a bacterium Xanthomonas campestris pv. campestris were identified to be associated with the disease. The higher incidence of the disease as well as the shorter incubation period was found when X.c. pv. campestris inoculum was applied. Under natural epiphytotic conditions, the disease appeared in the month of February. The correlation coefficients of incidence and severity with temperature were highly significant and positive and it was significant and negative with the relative humidity. Multiple regression analysis of the data revealed that only temperature had significant positive effect on the disease development. The spray application of Paushamycin plus Hexacap 50 WP besides being the most efficacious also resulted in the highest seed yield in vivo followed by Streptocycline plus Hexacap 50 WP. Bordeaux mixture plus Sreptocycline spray was the least efficacious treatment which gave the lowest disease control and the minimum seed yield.


Satya Pal Goyal (H-89-14-D)

2. Name of Major Advisor Dr. C.L.Jandaik3. Title of Thesis Interaction of weed fungi with Agaricus bisporus

(Lange) Imbach and their management4. Year of completion of Degree 19935. Abstract of Thesis

Among different weed fungi (Trichothecium roseum, Trichoderma viride, Chaetomium globosum, Diehliomyces microsporus, Papulaspora byssina, Myceliophthora lutea and species of Coprinus, Oedocephalum, Pythium, Sepedonium and Sporendonema) recorded, the frequency and incidence of P. byssina was maximum. Growth (radial and diametric) of Agaricus bisporus was significantly inhibited irrespective of weed fungi except in case of P. byssina. Cultural filtrates of various weed fungi, significantly inhibition of A. bisporus except P. byssina where inhibition of growth of A. bisporus was non-significant as compared to control. T. viride and C. globossum were found to produce volatile metabolites and resulted in 7.82 and 2.17 per cent inhibition, respectively of A. bisporus growth. Comparative rate of growth of all the weed fungi was much faster as compared to A. bisporus growth on pasteurized compost. When different weed fungi were grown individually in presence of A. bisporus on pasteurized compost, all the weed fungi significantly inhibited growth of A. bisporus. Fifty ppm of Bavistin, Topsin-M, Indofil M-45 and Hexacap did not exert any inhibitory effect on the growth of A. bisporus whereas, growth of T. viride and P. byssina was inhibited 100 per cent. There was significant increase in yield of A. bisporus irrespective of weed fungi inoculation with single spray of either Bavistin, Topsin-M or Indofil M-45. Amendment of compost with different plant materials produced higher yield as compared to control. Inoculation of various weed fungi in spawned compost amended with different plant materials produced significantly more yields with all the weed fungi. Development of various weed fungi was favoured by higher compost moisture (75%) and temperature (25oC).


Kulbir Singh Dhanju (H-89-11-D)

2. Name of Major Advisor Dr. S.C.Chowfla3. Title of Thesis Epidemiology and management of virus

disease(s) of French bean (Phaseolus vulgaris L.)4. Year of completion of Degree 19935. Abstract of Thesis

Surveys recorded in HP, an incidence of virus disease(s) ranging from 0.00 to 100 per cent in French bean. The symptoms produced by the virus(es) were mosaic, vein-banding, puckering, distortion of infected leaves etc. Virus isolates were sap as well as two aphid vectors viz., M. persicae and A. craccivora transmissible except one isolate (FB-8), which was only transmitted by M. persicae. The host range of the virus isolates was restricted to the families chenopodiaceae, leguminosae and solanaceae. The TIP, DEP and LIV of all isolates ranged between 55-60oC, 10-3-10-4, 1-3 days at room temperature and 3-5 days at refrigerated temperature, respectively. Long flexuous, rod shaped particles of the virus typical of potyvirus group were observed under electron microscope. ISEM studies showed good trapping of virus particles with BCMV for all the isolates, except FB-8, which showed trapping with BYMV. On the basis of different identification parameter isolates FB-1 to FB-7 identified as strain(s) of BCMV, while FB-8 as bean yellow mosaic virus. Virus disease incidence in French bean was mainly influenced by vector population, mean air temperature and wind velocity. For management of disease, early planting, more plant density, yellow polythene mulch and Karate as insecticide proved effective as red veining disease incidence. Out of 177 germplasm collection of French bean, EC 94469 and EC 94929 were found highly resistant against BCMV.


Satish Kumar Sharma (H-89-13-D)

2. Name of Major Advisor Dr. V.K.Gupta3. Title of Thesis Studies on management of white root rot of apple4. Year of completion of Degree 19935. Abstract of Thesis

Incorporation of neem, mahua and castor cakes and chopped needles of deodar, chir and kail pines, prior to inoculation of pathogen was found quite effective in reducing root rot of apple in pots. The reduction was 52.38, 45.84, 42.86, 69.64, 58.983 and 47.62 per cent in these treatments, respectively. Fertilization of apple seedlings with calcium ammonium nitrate and single super phosphate was observed to reduce the incidence of disease by 61.44 and 43.86 per cent in pots and 47.41 and 39.63 per cent in field, respectively. Trichoderma viride, T. harzianum, T. hamatum, T. koningii and G. virens. Enterobacter aerogenes a bacterial antagonist was also quite effective and produced inhibition zone of 4.00 mm against Dematophora necatrix. Application of E. aerogenes, T. viride, T. harzianum and G. virens, two weeks prior to inoculation of D. necatrix delayed the appearance of disease by 24, 5, 4 and 4 days and mortality of plants by 74.74, 13.10, 13.69 and 11.43 per cent, respectively in pots. Five applications of E. aerogenes, T. viride, T. harzianum and G. virens resulted in 75.00, 47.62, 41.07 and 37.50 per cent disease control in pots and 55.19, 40.00, 40.65 and 39.82 per cent under field conditions, respectively. Pre, simultaneous or post-inoculation (pathogen) application of combination of four chemicals namely Bavistin + Furadan + phorate + Dithane M-45 (0.1% + 10 g/plant + 10 g/plant + 0.25%) in pots as well as under field conditions completely prevented the appearance of the disease. All the fungal antagonists four effective against D. necatrix were completely inhibited by Bavistin (25 ppm) in vitro. Bavistin (200 ppm), phorate (1000 ppm) and Dithane M-45 (2000 ppm) did not inhibit the growth of E. aerogenes. Pre-inoculation application of E. aerogenes along with Bavistin (0.1, 0.05, 0.025 %) gave 85.72, 80.72, 80.96 and 66.67 per cent control of disease.


Rakhi Chopra (H-90-13-D)

2. Name of Major Advisor Dr. V.K.Gupta3. Title of Thesis Studies on bacterial spot of stone fruits with

major emphasis on almond4. Year of completion of Degree 19945. Abstract of Thesis

Survey of different fruit growing areas in the districts of Kullu, Sirmour and Solan of Himachal Pradesh revealed that the leaf spot and fruit gummosis was present in all the localities. The causal bacterium was identified as Xanthomonas campestris pv. pruni. Studies on the cross virulence of X.c. pv. pruni isolates on two cultivars each of almond, apricot, peach and plum clearly indicated that these differed in the pathogenic reaction. Out of ten species of fungi and seven of bacteria isolated from almond phylloplane, Bacillus spp., B. subtilis, Erwinia herbicola, Flavobacterium sp., Aspergillus sp., Fusarium sp., Penicillium sp. and Rhizopus sp. were found inhibitory against X.c. pv. pruni in vitro. Mean minimum temperature, relative humidity and total rainfall had a positive influence on epiphytic population, however, increase in maximum temperature decreased the population of X.c. pv. pruni. Five sprays of Streptocycline (100 ppm) along with Blitox-50 (0.2%) immediately after the appearance of the disease accompanied by 4 subsequent sprays at 15 days interval were found to be best in reducing both the leaf spot and fruit gummosis phases.


Anil Kumar Handa (H-91-9-D)

2. Name of Major Advisor Dr. S.C.Chowfla3. Title of Thesis Identification and management of viruses

infecting chillies in Himachal Pradesh4. Year of completion of Degree 19955. Abstract of Thesis

Investigations were undertaken to identify different viruses/strain responsible for causing chilli mosaic. The symptoms evolved chilli mosaic disease were chlorosis, mosaic, mottling, green vein banding, thickening of leaf veins, puckering and blistering of the infected leaves, stunting of plants, flower dropping and fruit deformities. All isolates were found to be sap transmissible as well as by aphids. The host range was restricted to the family solanaceae. TIP, DEP and LIV of the virus isolates ranged between 55-70oC, 10-3 - 10-4, 3-4 days at room temperature and 7-13 days at refrigeration respectively. Electron microscopic studies revealed presence of flexuous rods of size 730-750 x 11-12 nm. Lamellar aggregates were also observed in infested samples which are typical of potyvirus group. Penicillin and alkaline phosphate based DAC-ELISA tested –ve against BCMV, BYMV, PMV and PSbMV. Solanum nigrum, Datura metel var. fastusa, Lavicantdra physalaroides were potential reservoir of chilli virus. Epidemiological studies showed that the disease incidence was influenced by air temperature, RH and vector population. Early planting of chilli and plant spacing of 30x30 cm showed less disease incidence. Use of polythene mulches not only reduced the disease incidence but also increased the dry pod yield significantly. Yellow polythene mulch was the best in reducing the disease incidence. Maize used as barrier crop in combination with metasystox insecticidal application in chilli plantations was most superior among the various combinations in management practices against virus mosaic disease. Five varieties/collections/lines of capsicum were found highly resistant under glasshouse as well as field conditions.


Narender Kumar Bharat (H-92-11-D)

2. Name of Major Advisor Dr. L.N.Bhardwaj3. Title of Thesis Studies on the influence of vesicular-arbuscular

mycorrhae on white root rot of apple4. Year of completion of Degree 19965. Abstract of Thesis

Amongst the six VAM fungi namely, Glomus mosseae, G. fasciculatum, Acaulospora laevis, Gigaspora gilmorei and Glomus spp. (Local apple isolate), isolate (Glomus spp.) was found most efficient in colonizing roots of apple seedlings and reducing the disease severity. Pre-inoculation of apple seedlings with local VAM isolate (Glomus spp.), 60 days prior to Dematophora necatrix inoculation, was adjudged the best treatment in reducing disease severity and increasing VAM colonization. Increase on plant growth parameters such as height, stem diameter, leaf area, root length and dry root and shoot weight was also found significantly higher in Glomus spp. inoculated seedlings in comparison to non-mycorrhizal pathogen inoculated and pathogen inoculated seedlings. The chlorophyll content in the leaves of mycorrhizal/non-mycorrhizal seedlings increased significantly under all VAM applications, however, it decreased in mycorrhizal and non-mycorrhizal pathogen inoculated seedlings. Similarly the total phenol, K and P contents were also found significantly higher in VAM inoculated seedlings in comparison to non-mycorrhizal seedlings with maximum in Glomus spp. inoculated seedlings. Application of fungicides namely, carbendazim, CuSO4 and Aureofungin suppressed the VAM colonization and sporulation initially but increased gradually thereafter, however, drenching of carbendazim had less effect on VAM colonization and sporulation than others. Combined effect of application of Glomus spp. and carbendazim (0.1%) increased the colonization and reduced disease severity significantly over other treatments.


Vishvanath Gade (H-92-10-D)

2. Name of Major Advisor Dr. J.L.Kaul3. Title of Thesis Studies on biological control of important

postharvest diseases of apple4. Year of completion of Degree 19975. Abstract of Thesis

The 150 bacterial, 53 yeasts and 35 fungal isolates from apple leaves and fruit of neglected orchards, only six bacterial, three fungal and eight yeast species indicated positive antagonistic interactions. The yeast antagonist Thodosporidium toruloides was most potent antagonist. The sensitivity of Rhizopus stolonifer was highest while Glomerella cingulata exhibited lowest sensitivity to antagonist(s) while G. cingulata sensitivities exhibited by Penicillium expansum and Monilinia fructigena were significantly higher than G. cingulata. Highest protection against the test pathogen was achieved with lowest (104 spores/ml) pathogen and highest (108 spores/cfu/ml) antagonist concentration. Higher antagonistic activity was assessed in presence of inorganic salts than the amino acids. Culture filtrates of Candida rhagii and Rodotorula glutinis gave maximum protection against the test pathogens. Significant inhibitions were also affected by filtrates of Aureobasidium pullulans and C. cantarellii. The antagonists performance was highest at 5oC which decreased with the increase in temperature (5 to 30oC). Plant extract (latex) of E. royleana provided highest protection against the test pathogens followed by P. granatum fruit extract. Penicillium expansum exhibited highest sensitivity to the plant extracts while R. stolonifer was insensitive.


Dharmesh Gupta (H-95-20-D)

2. Name of Major Advisor Dr. S.C.Chowfla3. Title of Thesis Characterization of viruses causing leaf curl

disease of tomato in Himachal Pradesh4. Year of completion of Degree 19995. Abstract of Thesis

The incidence of leaf curl disease ranged between 3.0 to 75.0 per cent and 3.5 to 70.0 per cent during the cropping seasons of 1997 and 1998, respectively. None of the isolates were transmitted by sap and by different species of aphids tested but were readily transmitted through grafting and by the whitefly, Bemisia abaci. The host range of the virus isolates was restricted to the plants belonging to the families asteraceae and solanaceae. Even a single whitefly was able to transmit bot the leaf curl isolates. Electron microscopic studies revealed that both the isolates (TLC-1 and TLC-2) consisted of geminate particles measuring 17 x 29 nm and 17 x 30 nm, respectively. Immunosorbent electron microscopy (ISEM) showed that both the isolates exhibited enhanced trapping of the virions with antiserum against Indian cassava mosaic virus (ICMV). Simple correlation coefficients of disease incidence with temperature, relative humidity and vector population were found to be highly significant during both the years. Early planting of tomato showed less disease incidence (32.50 and 36.25 %) during 1997 and 1998 cropping seasons than those planted on later dates. The use of different coloured polythene mulches (especially yellow) not only reduced the disease incidence but also increased the yield substantially as compared to the control. Out of eighty seven cultivars tested, only EC-104395 was found to be resistant to the virus both under field and glasshouse conditions.


Vidya Sagar Verma (H-94-10-D)

2. Name of Major Advisor Dr. S.K.Sharma3. Title of Thesis Studies on non-chemical management of mango

wilt in nurseries4. Year of completion of Degree 19995. Abstract of Thesis

Effect of soil amendment with oil cakes, fresh as well as dry plant materials, biocontrol agents and soil solarization was seen on the management of mango wilt caused by Fusarium solani. Oil cakes and plant materials increased the population of soil fungi, bacteria and actinomycetes whereas sawdust decreased the microbial population. All the amendments reduced pathogen population as well as wilt incidence and improved plant health. Among the oil cakes, neem cake (2% w/w) when applied one month prior to pathogen inoculation recorded the minimum pathogen population and maximum disease control with highest shoot length, root length, shoot weight and root weight. Application of Cannabis leaves (2% w/w) one month prior to pathogen inoculation recorded the minimum pathogen population and highest disease control as well as shoot and root lengths and weights after 90 days of inoculation. All the fungal antagonists viz., Trichoderma harzianum, T. viride, T. hamatum, Gliocladium virens and bacterial antagonists B1 and B2 strains of Bacillus sp. inhibited the wilt pathogen both under in vitro as well as in vivo studies. Inoculation of antagonists of sterilized pot soil 10 days prior to pathogen inoculation recorded the minimum pathogen population and maximum disease control. Among the polythene tarps of different thickness used for soil solarization, the thinnest tarp (25 µm) recorded the maximum increase in soil temperature of 13.7oC and 12.7oC under irrigated and unirrigated conditions, respectively as compared to untarped control. The rise in temperature was maximum in the top 10 cm layer which successively decreased with increase in soil depth. Pathogen population was completely eliminated after 45 days of solarization under 25 µm tarp in irrigated conditions and after 60 days under all the tarps in irrigated as well as unirrigated conditions. There was complete control of wilt in solarized plots. The thinnest tarp (25 µm) recorded the maximum shoot and root lengths as well as weights in irrigated treatments. Sol solarization considerably reduced the populations of soil nematodes as well as weeds. Nitrogen, potassium, organic carbon contents and soil pH increased whereas phosphorus content decreased in solarized soil. Solarization of irrigated soils with 25 µm tarp alone or in combinations with organic amendments (neem cake and Cannabis leaves) as well as fungal antagonists (T. harzianum and G. virens) completely eliminated the pathogen population upto a soil depth of 30 cm, no wilt symptoms appeared upto the end of the trial recording the highest improvement in plant health.


K. Abraham Mathew (H-95-21-D)

2. Name of Major Advisor Dr. K.R. Shyam3. Title of Thesis Epidemiology, variability and management of

Angular leaf spot of French bean4. Year of completion of Degree 19995. Abstract of Thesis

The incidence of the disease ranged from 5.0 to 100.0 and 60.0 to 100.0 per cent and severity from 3.14 to 80.0 and 25.0 to 60.66 per cent during 1996 and 1997 crop season. Potato dextrose agar (PDA) supplemented with 1 per cent bean seed extract, supported maximum mycelial growth while 25oC found optimal for the growth of the pathogen. Increase in leaf wetness durations from 3 to 9 h showed a corresponding decrease in incubation period from 12 to 9 days whereas further increase in leaf wetness did not exert any effect on incubation period. However, intermittent wetness upto 3 cycle (12 h dry and 12 h wet) were found effective to increase number of lesions per leaf. Higher relative humilities (>90%) favoured disease development. Regression equation between disease severity and environmental factors explained 69.33 per cent change in the disease severity to be due to rainfall, soil moisture and relative humidity. Thus high humidity (> 80%) coupled with moderate temperatures (25±1oC) favour disease development. Conidial release of Phaeoisariopsis griseola was found to be favoured by temperature (23-24oC), high relative humidity (>90%), prevalence of dew (20.00 to 08.00 h) and a dark period. The losses in green pod yield ranged from 53.76 to 69.33 per cent and seed yield from 51.92 to 64.55 per cent among different French bean cultivars. Out of 173 cultivars/lines screened against P. griseola under natural epiphytotic conditions, none was immune to the disease. However, lines EC 44758, EC 97830 and NIC 14402 exhibited highly resistant to resistant reactions. Bean sowing after 20 th August showed a signification reduction in disease severity. However, early sowing (July) resulted in increased seed germination and yield. Wider row to row and plant to plant spacing of 60 x 22.5 cm (bush type) and 120 x 22.5 cm (pole type) registered minimum disease severity while narrow plant spacings registered higher disease severity. Inter-cropping of French beans with maize was found to be highly effective to reduce the disease severity. Organic amendments like cakes of cotton and mustard were found effective to reduce the disease severity and increase green pod yield. Application of Bavistin as seed treatment (0.1%) followed by foliar sprays (0.05%) proved effective in reducing disease severity and increased seed yield.


Sanjeev Sharma (H-96-10-D)

2. Name of Major Advisor Dr. R.C.Sharma3. Title of Thesis Studies on epidemiology and management of

poplar leaf rust4. Year of completion of Degree 20005. Abstract of Thesis

Poplar leaf rust caused by Melampsora species is of world wide occurrence. In India, the disease is caused by an indigenous species (M. ciliata) reported only from western Himalayas. Rust is prevalent in moderate to severe from in all the four agro-climatic zones of Himachal Pradesh. The severity of disease ranged from 1 to 85 per cent with maximum in zone-II. The overall severity of the rust in the state was 32.54 per cent. Pattern of urediniospore production and urediniospore size on different poplar genotype revealed the influence of plant genotype and environment. Rust assumed an epiphytotic status in the months of July and August. Incubation period for flecking was positively correlated with latent period for eruption of first and fifty per cent uredinia while negatively correlated with uredinia per leaf disc. Isolates of the pathogen behaved differently in the same host genotype and isolate I4 (Nirath) was found to be more virulent. Temperature of 20oC and 100 per cent relative humidity were optimal for the germination of urediniospores. Urediniospores lost their viability within 10 days at ≥ 20oC. Disease incidence was correlated with stomatal density while pore size had no role in regulation of disease. Variation in protein and phenolic contents was also observed in Populus species/cultivars/hybrids/clones but no correlation could be established with disease incidence. Leaf emergence was positively correlated but initiation of disease. None of the Populus ciliata clone was disease free while large number of hybrids with inhibition of disease. None of P.deltoides remained rust free. Prior inoculation of antagonists (Alternaria alternata and Cladosporium oxysporum) resulted in least germination of urediniospores, minimum eruption of uredinia per leaf disc and maximum parasitization of urediniospores and uredinia. Urediniospores viability loss was less and at a slower rate at 10oC and at lower concentration of antagonists than at 25oC and at higher concentration of antagonists. Reduction in viability of urediniospores was rapid with A. alternata and C. oxypsorum. Out of thirteen fungicides tested, EBI fungicides (Score, Topas and Contaf) exhibited god control of rust disease.


Mamta Sharma (H-96-9-D)

2. Name of Major Advisor Dr. S.K.Sharma3. Title of Thesis Non-chemical methods for the management of

white root rot of apple4. Year of completion of Degree 20005. Abstract of Thesis

Effect of organic amendments, biocontrol agents and soil solarization was seen on soil microflora and management of white root rot of apple caused by Dematophora necatrix. Addition of oil cakes and plant materials increased the population of soil fungi, bacteria and actinomycetes, whereas, sawdust reduced microbial population. Amongst the organic amendments tested, neem cake and deodar needles gave maximum disease control and also delayed the symptoms when applied one week and two months prior to the pathogen inoculation, respectively. All the fungal and bacterial antagonists viz., Trichoderma viride, T. harzianum, T. hamatum, Gliocladium virens, Bacillus sp. and Pseudomonas sp. inhibited the growth of D. necatrix both under in vitro and in vivo conditions. Applications of fungal antagonists to sterilized pot soil 15 days prior to pathogen inoculation recorded maximum disease control. Similarly, application of Bacillus sp. and Pseudomonas sp. 6-8 days prior to the pathogen inoculation gave maximum control of root rot. In addition to disease control, all the bacterial antagonists improved the plant health. D. necatrix was found to be sensitive above 40 under in vitro conditions. Among the polyethylene tarp of 25 µm and 50 µm used for soil solarization, the thinnest tarp (25 µm) record 8-9oC increase in soil temperature as compared to unsolarized soils. Rise in temperature was maximum in the top 10 cm layer that decreased with corresponding increase in soil depth. D. necatrix was completely eradicated upto 30 cm depth under both the mulches in irrigated and unirrigated soils. Soil solarization considerably reduced the population of fungi, bacteria and actinomycetes, however, the population of thermotolerant and thermophilic fungi increased. Nitrogen, potassium, organic carbon and electrical conductivity increased, whereas, phosphorus content decreased in solarized soil. No disease was recorded in solarized plots amended with neem cake, T. viride, T. harzianum and Bacillus alone as well as in combination with each other even after one year of solarization and also improved plant health.


Arti Shukla (H-96-8-D)

2. Name of Major Advisor Dr. K.R.Shyam3. Title of Thesis Studies on bacterial spot of tomato caused by

Xanthomonas vesicatoria (Doidge) Dye4. Year of completion of Degree 20015. Abstract of Thesis

Bacterial spot of tomato caused by Xanthomonas vesicatoria (Doidge) Dye was found to occur in moderate to severe form in various tomato growing areas of Solan and Sirmour districts of Himachal Pradesh. Pathogen produced symptoms on all above ground parts of the plant with shorter incubation period on fruits in comparison to leaves and stems. Maximum growth of the bacterium was recorded at 30oC and 7.0 pH. Among the different liquid media, nutrient broth and dew water favoured maximum growth of the bacterium. Epidemiological studies revealed that an inoculum density of 3.0x108 cfu/ml was optimum for the initiation of disease and maximum disease severity was recorded in case of wound inoculated 55 days old plants maintained at 28oC coupled with 100 per cent relative humidity for 24 h. There was increase in disease severity with the increase in leaf wetness duration. Temperature, relative humidity and soil moisture considerably influenced bacterial spot development. Pathogen remained viable for 3 ½ months in inoculated seeds under laboratory conditions (23-25oC). Among the various chemical evaluated in vitro at varying concentrations against X. vesicatoria by turbidimetric, well and Thompson’s methods; Streptocycline (100 ppm) and combination of Streptocycline (10 ppm) plus Blitox-50 (2000 ppm) provided maximum inhibition of bacterial growth. Pine needles and eucalyptus leaves extracts @ 40 % w/v also inhibited the growth of the test pathogen. Among the different thermal, chemical and chemothermal treatments, hot water (50oC) treatment for 0.5 h, Streptocycline (0.01%) treatment for 1 h and Streptocycline (0.01%) + hot water (50oC) treatment besides supporting substantial seed germination. Under pot culture conditions, the latter combination resulted in maximum disease control. Dipping the tomato seedlings in Streptocycline solution (0.01%) for 1 h effectively reduced the severity of bacterial spot and maximum control was achieved through protective as well as eradicative spray applications of Streptocycline (0.01%) + Blitox-50 (0.2%) followed by Blitox-50 (0.2%) + Dithane M-45 (0.2%). Among the different soil amendments and application of mulches, only pine needles mulch was found effective to some extent in reducing disease severity. However, among various integrated disease management treatments, higher efficacy and maximum fruit yield were recorded in case of combination of seed treatment (hot water treatment at 50 oC followed by seed dip in Streptocycline (0.01%) for 0.5 h, pine needles mulch and six sprays of Blitox-50 (0.2%) plus Streptocycline (0.01%).


Usha Devi (H-97-18-D)

2. Name of Major Advisor Dr. S.C.Chowfla3. Title of Thesis Studies on radish mosaic in Himachal Pradesh4. Year of completion of Degree 20015. Abstract of Thesis

Sixteen isolates were collected and further grouped into six groups on the basis of their reaction on indicator plants. all the isolates were sap as well as transmitted by aphid vectors viz., Myzus persicae and Brevicorynae brassicae. The virus isolates infected members of families amaranthaceae, chenopodiaceae, cruciferae, compositae and solanaceae. The biophysical properties i.e. TIP, DEP and LIV of all the isolates ranged between 60-65oC, 10-2 to 10-3, 3-4 days at room temperature and 5-6 days at refrigerated temperature (5±1oC), respectively. Electron microscopic studies revealed that all the isolates had rod shaped virus particles measuring 730-750 nm x 12-14 nm. Cyto-pathological studies indicated the presence of cytoplasmic inclusions which consisted of pin wheels and lamellar aggregated. ISEM studies showed that all isolates exhibited enhanced trapping of virions with antibodies against TuMV. In ELISA tests, virus reacted positively with antiserum against TuMV. On the basis of these studies isolates were found to belong to family Potyviridae, Genus potyvirus and group III. Simple correlation coefficients of disease incidence with temperature and vector populations were found to be highly significant during both the years of investigations. Multiple correlation coefficients between disease incidence and group of independent variables was 0.9632 and 0.9483 during 1998-99 and 1999-2000, respectively. Maximum yield was recorded in radish crop transplanted on 27th October and 11th November during 1998-99 and 1999-2000, respectively. Planting of barrier crops (oat, wheat and barley) significantly reduced the disease incidence. Among insecticides used, Rogor was adjudged to be the most effective. Acetone, alcohol and water fractions of Centella asiatica, Vitex negundo, Asparagus adscendens and Ocimum sanctum at different concentrations inhibited TuMV. Pre-inoculation sprays were found to be significant than post-inoculation sprays.


Vijay Kumar Thakur (H-97-19-D)

2. Name of Major Advisor Dr. T.R.Shandilya3. Title of Thesis Studies on mycoflora of compost for Agaricus

bisporus (Lange) Imbach.4. Year of completion of Degree 20015. Abstract of Thesis

Micro-organisms recorded at 25±1oC were more than at 45±1oC during outdoor composting (phase I). While during phase –II, maximum number of propagules were found at 45±1oC than at 25±1oC. After pasteurization, among population of thermophilic fungi expressed as colony forming unit (cfu), Scytalidium thermophilum showed maximum population (4.20x103) followed by Theremomyces lanuginosus (1.20x103) and Gilmaniella humicola (1.00x103). Dual culture studies revealed that S. thermophilum and G.humicola increased the growth of Agaricus bisporus by 22.6 and 4.3 per cent, respectively. Studies on effect of incorporation of thermophiles on the downward mycelial growth of A. bisporus indicated that S. thermophilum when added to the compost showed maximum mycelial growth of A. bisporus after first, second and third week of incubation. All the three test fungi when added in the compost took significant lead in the growth of A. bisporus amongst all the combination treatments. In physiological studies, optimum temperature and pH for the growth of all the three test thermophiles was found to be 45oC and 7.0, respectively. Maximum quantity of compost (260 kg) was produced when mixed culture of three fungi (G. humicola + S. thermophilum + T.lanuginosus) was inoculated in the compost pile. Mixture of cultures of different fungi when inoculated in the compost at spawning gave 21.3 per cent increase in the yield of mushroom over control. Mushroom bags filled with compost from all the treatments (mixed culture of thermophiles inoculated at –2, 0, +2, +4, +6, +8, +10 day and spawning time) gave 14.90 per cent higher yield than the control.


ShaliniVerma (H-97-17-D)

2. Name of Major Advisor Dr. N.P.Dohroo3. Title of Thesis Studies on Fusarium wilt of pea (Pisum sativum

L.)4. Year of completion of Degree 20015. Abstract of Thesis

Fusarium wilt caused by Fusarium oxysporum Schl. f.sp. pisi Snyd. and Hans. Is an important disease of autumn pea occurring in moderate to severe form in major pea growing areas of Himachal Pradesh. Pre-emergence rot and Fusarium wilt increased with an increase in the inoculum concentration as well as treatment period of F.o.f.sp. pisi. Inoculation by top covering of seeds with the inoculum as well as sick plot technique were found rapid and easy methods of proving pathogenicity of F.o. f.sp. pisi. Mycoflora viz., Gliocladium virens, Dactylaria sp., Geotrichum sp., Cladosporium cladosporioides, C. herbarum, Rhizopus stolonifer, Rhizopus sp., Pythium ultimum, P.aphanidermatum, Absidia clindrospora, Absidia sp. and Mucor sp. were found new additions to mycoflora occurring on pea. Morphological, cultural and pathogenic variability existed among the isolates and clones (Fop II) of F.o.f.sp. pisi. Soil hydrothermal regimes i.e. soil moisture and soil temperature considerably influenced wilt of pea. Early sowing, wider seed spacing, seed treatment with Bavistin (0.1%), Kri-benomyl (0.1%), T. harzianum, T. viride, Dithane M-45 (0.25%) + T. harzianum and Dithane M-45 (0.25%) + T. viride checked incidence of the disease. Garlic extract significant inhibited mycelial growth of F.o. f.sp. pisi and reduced incidence of the disease to a considerable extent. VAM population especially Glomus spp. was found to be augmented in rhizosphere soil of healthy plants as compared to wilt affected pea plants. Nevertheless, it reduced the pre-emergence rot and Fusarium wilt of pea, and resulted in increase in the plant vigour. EC-41311, Selection I, DRP-3, NDVP-5, JP-179, JP-1130, HP-1140, S-45, S-17, DRP-4 and T-17 were found to be resistant while EC-41224, P-1542, S-24, S-25 and Sel 8-1 were found as moderately resistant under greenhouse conditions. Under natural epiphytotic conditions, Selection I NDVP-5, DRP-3, JP-1130, JP-170, JP-1140, DRP-4, Azad P-1 and P-1542 recorded minimum Fusarium wilt, apparent infection rate and AUDPC.


Deepika Sood (H-97-13-D)

2. Name of Major Advisor Dr. R.L.Sharma3. Title of Thesis Studies on stem end rot of pears caused by

Phacidiopycnis piri (Fuckel) Weindlmayr4. Year of completion of Degree 20015. Abstract of Thesis

Pear fruits are highly susceptible to stem end rot caused by Phacidiopycnis piri (Fuckel) Weindlmayr in European countries and disease has assumed importance in HP. Disease incidence during the year 1999 and 2000 varied from 2.5 to 9.78 per cent with a mean per cent incidence of 5.23. The fruits produced typical symptoms of the rot on inoculation. P. piri gained successful entry through stalk end (intact and removed) and injured surface. The pathogen could infect apple, peach, apricot and plum fruits. Richard’s medium supported maximum vegetative growth of the test fungus. Optimum temperature for vegetative growth of P. piri was 25oC whereas range of 3.0 to 4.5 pH favoured better growth of P. piri. The test fungus preferred sucrose among carbon sources and glycine among nitrogen sources for its vegetative growth. Pear fruit cultivars viz., Bargument, Beurre Hardy, Max Red Bartlett, Kashmir pear and Beurre Baltira Giffard were somewhat tolerant to P. piri. Among qualitative characters, pH and titratable acidity exhibited significant positive correlation with stem end rot whereas fruit firmness, total phenols and OD phenols were significantly negatively correlated. Different pear cultivars revealed significant reduction of total soluble solids (TSS), titratable acidity, ascorbic acid, total, reducing and non-reducing sugars, total phenols and orthodihydric phenols. Management of storage temperature and hydro-cooling were highly effective in reducing stem end rot incidence. Fumigation with sodium or potassium metabisulphite was superior tin checking the disease. Bavistin wrappers and Sta-Fresh 960 coating exhibited significant protection of pears against stem end rot. Bavistin and Stop sprays among systemic fungicides gave significant control whereas among non-systemic fungicides was better as protectant (pre-inoculation treatment) rather than eradicant (post-inoculation treatment). Fungal antagonists viz., Trichoderma viride, T. longibrachiatum and T. hamatum gave maximum inhibition of mycelial growth of P. piri. Antagonist protection was higher when applied at concentration of 108

spores/ml before inoculation. Cent per cent inhibition of mycelial growth of P. piri was obtained with cinnamon, clove and mint oil at 50, 100 and 250 ppm concentrations, respectively. Pre-inoculation treatment with plant extracts of aloe (Aloe barbadensis), jangli gainda (Tagetes minuta), pipermint (Mentha piperita) and geranium (Pelargonium graveolens) provided significant control of Phacidiopycnis rot of pears.


Meenu Gupta (H-98-16-D)

2. Name of Major Advisor Dr. L.N.Bhardwaj3. Title of Thesis Studies on Phytophthora diseases of strawberry4. Year of completion of Degree 20015. Abstract of Thesis

The pathogenic fungus causing red stele was identified to be caused by Phytophthora fragariae Hickman, leather rot by P. cactorum (Leb. & Cohn.) Schroet. and fruit rot by P. nicotianae Breda de Haan, out of which P. fragariae was the most devastating one. In pathogenic tests, P. fragariae was able to infect only the strawberry roots while P. cactorum and P. nicotianae were pathogenic to fruits only. The soil temperature (15oC), soil moisture (100%), soil pH (5.5) and sandy loam will were found favourable for the development and spread of red stele. Various antagonists were tested for their inhibitory effect against all the three species of Phytophthora attacking strawberry under in vitro conditions of which maximum inhibition of all three Phytophthora spp. was shown by Trichoderma harzianum. Young cultures between the age of 3-6 days of fungal antagonists were highly efficient in the production of volatile substances therefore they were more capable in arresting the vegetative growth of these species. Amongst the bacterial antagonists, Pseudomonas fluorescens IISSR-8 and P. fluorescens T1R2K4 gave maximum inhibition against all these three species. Ovis and Unilax were found highly efficacious in inhibiting the vegetative growth of P. fragariae. The potency of these biocontrol agents was further tested under in vivo conditions. T. viride applied 14 days prior to inoculum by P. fragariae was found most effective in controlling red stele besides improving health of strawberry plants. Bacterial antagonists applied 8 days prior to pathogen inoculation resulted in maximum disease control and improved the health of plants. Drenching of Ridomil MZ was most effective than dip treatment in controlling red stele. The compatibility of fungal and bacterial antagonists was tested with fungicide under in vitro conditions. All the fungal and bacterial antagonists were compatible with Ovis and Unilax except T. harzianum which was incompatible with Ovis. Application of P. fluorescens IISSR-8 + Unilax, T. viride + Unilax and T. viride+ P. fluorescens T1R2K4 were most effective in reducing the severity of red stele beside improving the plant health. Under field conditions, treatments of antagonists and fungicides effectively managed the red stele and increased fruit yield. A treatment schedule comprising of dipping of runners in fungicide solution of Unilax at the time of transplanting along with application of T. viride in soil followed by Unilax drenching after one month and a spray of Unilax fruit formation stage effective managed red stele, leather rot and fruit rot of strawberry.


Rajender Singh Jarial (H-98-7-D)

2. Name of Major Advisor Dr. T.R.Shandilya3. Title of Thesis Studies on municipal waste as casing substrate

for Agaricus bisporus (Lange) Imbach.4. Year of completion of Degree 20025. Abstract of Thesis

The bulk density, particle density, porosity and water holding capacity of ten tested casing substrates ranged between 0.30 to 0.89 g/cm3, 0.56 to 1.28 g/cm3, 53.57 to 75.96 per cent and 47.29 to 127.10 per cent, respectively. The pH of the all the ten tested casing substrates ranged to an acceptable limit between 7.41 to 8.02, while salinity exhibited wide variation ranging between 66.00 to > 10,000 µ mhos/cm. The yield of Agaricus bisporus was positively correlated with physical properties (bulk density, particle density, porosity and water holding capacity), whereas, chemical properties (pH and electricity conductivity) were negatively correlated. The coefficient of multiple determination revealed that 71.79 per cent variation in the mushroom yield was due to these physical and chemical parameters under investigations. Municipal waste fed to earthworms – leached + vermicompost – leached + farm yard manure (1:2:2, v/v/v) gave significantly higher yield amongst all the test combinations. Six species of actinomycetes (Brevibacterium mebrellneri, Exguobacterium acetylicum, Micrococcus lylae GC sub group A, Micrococcus luteus GC subgroup C, Gordona rubropertinctus and Deinococcus erythromyxa), two species of bacteria (Pseudomonas sp. and Bacillus megaterium) and seven species of fungi (Aspergillus flavus, A. wentii, A. fumigatus, Penicillium brevicompactum, Cladosporium cladosporoides, Pythium sp., Mycelia sterlia), were isolated from different casing media. The population of actinomycetes as well as bacteria was found to be maximum at +21 days after casing. A positive and significant correlation was recorded between the population of bacteria as well as actinomycetes between +14 and +21 days of casing which coincided with pin-head formation. Interaction studies between growth of Agaricus bisporus and microflora (actinomycetes, bacteria and fungi) revealed that there was no inhibition/enhancement in the growth of A. bisporus mycelium. Casing moisture content of 61 per cent proved better for early pinning and yield of A. bisporus. Addition of grain spawn and impregnated compost (spawn run compost) at the time of casing in all the casing combinations resulted in higher yield and early pin-head formation of A. bisporus.


Ruchi Sood (H-98-3-D)

2. Name of Major Advisor Dr. N.P.Dohroo3. Title of Thesis Studies on leaf spot of ginger caused by

Phyllosticta zingiberi Ramakr.4. Year of completion of Degree 20025. Abstract of Thesis

Leaf spray method of inoculation (2 x 107 conidia/ml) was found to be best method of pathogenesis. In vitro growth of Phyllosticta zingiberi was recorded maximum on potato dextrose agar medium with maximum dry weight of the mycelium on Richards medium at 25oC and pH 4.5. Among carbon and nitrogen sources, mannitol and ammonium oxalate, respectively, supported maximum growth of test pathogen in the Richards medium. Considerable morphological, cultural and pathogenic variability existed among the isolates of the pathogen. P. zingiberi was found to be pathogenic on turmeric also. Influence of environmental factors viz., air temperature, relative humidity and rainfall on the disease development was found to an extent of 85.5 per cent. Pycnidia of P. zingiberi remained viable for 9 months in infected plant debris under natural conditions. The viability of the pathogen was found to be more in plant debris stored in nylon netted bags in comparison to polyethylene bags. Infected plant debris and rhizomes were found to severe as primary source of the inoculum. Early planting of ginger rhizomes, close spacing, inter-cropping of ginger with okra checked severity of the disease and increased fresh rhizome yield. Rhizome treatment as well as foliar sprays with Bordeaux mixture (1%), Companion (0.2%), Indofil M-45 (0.25%), Unilax (0.2%) and Baycor (0.05%) were also found effective in checking the disease severity. However, Bordeaux mixture and Companion effectively increased the fresh rhizome yield. Aloe (Aloe barberdensis) and tulsi (Ocimum sanctum) extracts inhibited the growth of the pathogen. Trichoderma harzianum and T. viride were found to inhibit the growth of the pathogen in vitro under glasshouse and field conditions. Integrated use of botanical, fungicides and BCA effectively reduced the disease severity under glass house conditions. Out of different varieties/germplasm screened, Lajhan, SG 503, Kali Chanog and Kindi were found resistant under glasshouse conditions. Out of 198 varieties/germplasm screened under field conditions only 52 showed moderately resistant reaction while, other were susceptible to highly susceptible.


Kumud Verma (H-97-14-D)

2. Name of Major Advisor Dr. K.R.Shyam3. Title of Thesis Studies on black rot of cauliflower caused by

Xanthomonas campestris pv. campestris (Pam.) Dowson


Black rot of cauliflower caused by Xanthomonas campestris pv. campestris (Pam.) Dowson was found to occur in moderate to severe form in various cauliflower seed producing areas of Solan, Kullu and Shimla districts of Himachal Pradesh. The incidence and severity of disease ranged from 14.25 to 100.00 and 11.11 to 93.00 per cent, respectively during 1999, 2000 and 2001. The optimum temperature and pH for growth of the pathogen were found to be 30oC and 6.5, respectively. Six liquid medium favoured the maximum growth of the bacterium with an increase in inoculum density from 3.2x105 to 6.2x109 cfu/ml, a progressive decline in incubation period and increase in disease severity, apparent infection rate and AUDPC of juvenile seedlings was recorded, while in mature plants, this trend was recorded upto 3.1x108 cfu/ml. Among different methods of inoculation, syringe followed by hydathode inoculation resulted in minimum incubation period and maximum disease severity, apparent infection rate and AUDPC. The plants upto an age group of 50 days were most susceptible for disease initiation and 65 days old plants were most vulnerable for disease progress. A decline in the virulence of the bacterium was recorded with increase in its age. Ranges of temperature and relative humidity between 25 to 35oC and 95.60 to 100.00 per cent, respectively were found to be optimum for disease initiation and development. Among the various meteorological factors, temperature influenced the disease positively and significantly during 1999, 2000 and 2001. The bacterium survived upto 188 days in cauliflower seeds stored under ambient conditions. Streptocycline (100, 150 and 200 ppm) and Streptocycline (100 ppm) + Bordeaux mixture (3000 ppm) were found to be effective against the pathogen under in vitro conditions. The extracts of Casuarina equiselifolia, Eucalyptus hybrida and Thuja campacta proved inhibitory. Chemical seed treatment with Streptocycline (100 ppm) + mancozeb (2500 ppm) for 3 h proved most efficacious in reducing the number of infected seeds with least deleterious effect on seed viability and resulted in 99.08 per cent disease control under glass house conditions. Seedling dip in Streptocycline (0.01 %) + mancozeb (0.25%) proved effective in increasing the incubation period and decreasing the disease severity, apparent infection rate and AUDPC. Mulch treatments with T. campacta and E. hybrida leaves resulted in 70.11 and 68.58per cent disease control, respectively. Foliar sprays of Streptocycline (0.01 %) + mancozeb (0.25%) resulted in 56.61 per cent disease control under glass house conditions. Integrated application of seed treatment with Streptocycline (0.01 %) + mancozeb (0.25%) for 3 h coupled with three foliar sprays of same combination along with Eucalyptus leaves mulch provided most efficacious disease management (59.27%) besides decreasing apparent infection rate and AUDPC to a considerable extent.


Reshu Garg (H-98-4-D)

2. Name of Major Advisor Dr. S.C.Chowfla3. Title of Thesis Epidemiology and management of turnip mosaic

in Himachal Pradesh4. Year of completion of Degree 20025. Abstract of Thesis

A mosaic disease of turnip was prevalent in Solan, Sirmour and Kullu districts of Himachal Pradesh. The incidence of disease ranged between 4-78 per cent and 8-80 per cent during 1999-2000 and 2000-2001, respectively. Thirteen isolates were collected and further grouped into five groups on the basis of their reaction of indicator plants. Al the isolates were sap as well as transmitted by aphid vectors viz., Myzus persicae and Brevicoryne brassicae. The virus isolates infected members of families amaranthaceae, chenopodiaceae, brassicaceae, compositae, cucurbitaceae, fabaceae, malvaceae and solanaceae. The biophysical properties i.e. TIP, DEP and LIV of all the isolates ranged between 60-65oC, 10-2-10-3 and 3-4 days at room temperature and 5-6 days under refrigerated conditions. Electron microscopic studies of the various isolates revealed the presence of long flexuous rod shaped virus particles typical of potyvirus group measuring 725-750 nm x 12-13 nm and inducing pinwheels and laminated aggregates. In serological studies using ELISA, the virus reacted positively with antiserum against TuMV. On the basis of these studies, the isolates were found to belong to family potyviridae, genus potyvirus and group III. Mean air temperature, relative humidity, wind velocity, cumulative rainfall and vector population influenced disease incidence to the extent of 97.96 and 93.35 per cent during 1999-2000 and 2000-2001, respectively. Maximum seed yield was recorded in the crop planted on 5 th October during both the years of experimentation at Chambaghat (Solan) and on 22nd September at Shimla. Planting of barrier crops such as wheat, oat and barley alone and in combination with insecticide was found effective in reducing the disease incidence. Karate was adjudged as the most effective insecticide.


Anita Sharma (H-98-2-D)

2. Name of Major Advisor Dr. S.K.Sharma3. Title of Thesis Non-chemical management of soil borne fungal

diseases of apple nurseries4. Year of completion of Degree 20025. Abstract of Thesis

The soil-borne diseases such as white root rot (Dematophora necatrix), collar rot (Phytophthora cactorum) and seedling blight (Sclerotium rolfsii) were found to be prevalent in apple nurseries of the state, maximum being in Solan district. Seedling blight was most prevalent recording 5.52 per cent incidence. The mixed culture of D. necatrix + P. cactorum + S. rolfsii (1:1:2) was found to be most virulent with incubation period of nine days. Plant oils such as clove, ginger, mentha and basil were found effective against these fungi under in vitro evaluation. Neem cake was also found most effective against D. necatrix, P. cactorum and S. rolfsii giving 41.74, 64.78 and 21.94 per cent inhibition of the fungi, respectively, whereas in pot culture studies neem cake gave 23.65 per cent control of these diseases. Oil cakes also improved the plant health significantly. Soil amendment with oil cakes increased fungal, bacterial and actinomycetes population. Among the fungal biocontrol agents, Trichoderma longibrachiatum and T. viride were found most effective giving 77.33 and 74.47 per cent control of these pathogens individually as well as their mixed culture. Among the bacterial antagonists Pseudomonas fluorescens IISR 8 was found most effective giving 53.65 per cent disease control. Soil application of biocontrol agents was proved to be better methods compared to seed and seedling dip treatment. T. longibrachiatum followed by T. viride was found most effective against these pathogens when applied as soil application. Dip treatment was more effective when seedlings were treated for 60 minutes as compared to 30 minutes. Biocontrol agents were also found to improve the plant growth parameters. Incidence of soil-borne fungal diseases was minimum in virgin land followed by agricultural land and was maximum in regular nursery site. Solarization with double layer of polythene was more effective in eradicating soil borne fungi as compared to single layer of polyethylene sheets. Interaction of soil solarization, organic amendments and biocontrol agents increased microbial population significantly. Solarized plots amended with neem cake and T. viride gave complete control of all the soil-borne diseases.


Bhupesh Kumar (H-97-12-D)

2. Name of Major Advisor Dr. L.N.Bhardwaj3. Title of Thesis Studies on collar rot of apple4. Year of completion of Degree 20025. Abstract of Thesis

Collar rot (Phytophthora cactorum (Leb. and Cohn.) Schroet) was found much higher in fruit bearing trees of pome and stone fruits than nursery plants falling in agro-climatic zone III. Graft union found at or near or below than soil level had high disease incidence (30.81%). The results of the cross inoculation revealed that apple isolate of P. cactorum was highly virulent on apple and less virulent on pear, peach, plum, apricot and cherry and vice-versa. Out of 16 host plant species tested, kainth and hazalnut were found less susceptible to collar rot pathogen. Morphologically all the five isolates of apple were similar but were found dissimilar pathologically. P1 isolate was found highly virulent and produced a lesion size of 58.33 mm on Malus prumifolia Shaishie with 72 hrs after inoculation by excised twigs method. A temperature of 25oC, soil moisture 90 per cent, soil pH of 5.0 and clay soil were found most conducive factors for the development and spread of collar rot. The soil temperature between 40-50oC for about 30 days was sufficient to kill the pathogen at a soil depth of 30oC under solarized conditions. Botanical pesticide Ovis and talk based formulation of Trichoderma longibrachiatum gave maximum disease control in orchard field conditions applied as soil mix as well as paint with Unilax (combi-fungicide of metalaxyl + mancozeb) during monsoon and winter, respectively. Six apple root stocks viz., M4, M21, M26, EMLA 111, Malus baccata Rohroo and M. prunifolia were found resistant against all the five isolate of P. cactorum.


Savita Jandaik (H-98-5-D)

2. Name of Major Advisor Dr. D.S.Guleria3. Title of Thesis Interaction of fungal pathogens with Agaricus

bisporus (Lange) Imbach and their management4. Year of completion of Degree 20025. Abstract of Thesis

Among different fungal pathogens recorded, the relative per cent occurrence and incidence of Verticillium fungicola and Cladobotryum dendroides were higher as compared to other fungal pathogens. The former required incubation period of 36 h irrespective of developmental stage of A. bisporus fruit bodies whereas latter needed 24 h incubation period when buttons and harvested pilei were inoculated and 72h in case of pinheads inoculation. The pathogen V. fungicola induced dry bubble disease, which was characterized by production of scleromoid (Sclerodermoid) masses of undifferentiated tissues, superficial necrotic lesions and stipe peeling. C. dendroides caused cobweb disease which is characterized as white mycelium covering stipe, pileus and gills and finally resulting in rotting of complete fruit bodies. The vegetative growth of both the pathogens was highest at 20oC and 6.0 pH whereas sporulation was more at 25oC and 6.0 pH. The temperature (25oC) and relative humidity (95%) that supported best growth of V. fungicola, were also suitable for sporulation of C. dendroides. Both the pathogens inhibited A. bisporus in paired cultures. The per cent loss in yield was more in case of C. dendroides than V. fungicola irrespective of stage of infection and inoculum load. Mycelia of both the pathogens could withstand 45o C for 30 minutes in wet state. Spores of V. fungicola were more tolerant than C. dendroides to external conditions and formalin exposures. Various plant extracts and biocontrol agents tried were not found effective. Two spray applications of Benlate (250 ppm) + formalin (1000 ppm) proved effective in minimizing losses in yield in relation to addition of inoculum at casing.


Sachin Upmanyu (H-98-6-D)

2. Name of Major Advisor Dr. S.K.Gupta3. Title of Thesis Epidemiology and management of root rot and

web blight of French bean caused by Rhizoctonia solani Kuhn


Root rot and web blight (Rhizoctonia solani Kuhn) appeared in moderate to severe form in major French bean growing areas of Himachal Pradesh. The disease was more severe on bush type cultivars than on pole types. Although morphological and cultural characters showed slight differences among the isolates, but studies on pathogenic variability demonstrated the existence of varied aggressiveness in each cultivar. Isolates I8 and I9 were the least sensitive to Bavistin while I10, I13 and I17 exhibited maximum sensitivity. On the basis of anastomosis behaviour, the isolates were placed in AG-1A, AG-1-1B and AG-4. Isolates also produced different banding patterns for esterase as well as NADH dehydrogenase. Isolates of AG-4 varied very little while AG-1-1B and AG-1-1A were slightly more variable. Root rot development was favoured at 80 per cent soil moisture and 25o C while the combination of latter with 100 per cent RH favoured web blight. Continuous leaf wetness of 12 h showed symptoms development after 26 h. However, intermittent leaf wetness upto 4 cycles (12 h wet/ dry) resulted in higher web blight severity. High soil moisture, RH (>80%) and moderate temperature (25 + 1oC) favoured disease development. Line ET 8396 showed resistant reaction among germplasm screened against the disease under natural epiphytotic conditions. Cultural practices viz., alteration of sowing dates, spacing and use of soil amendments proved quite effective to manage the disease, thereby suggesting their relevance for inclusion in integrated disease management programme. Foliar sprays of Bavistin (0.1%) and Folicur (0.05%) were most effective in reducing web blight severity while seed treatment with Bavistin (0.2%) in combination with foliar sprays were the most effective in reducing root rot incidence and web blight severity. Among biocontrol agents, Trichoderma harzianum I2 was found to be most effective against R. solani under in vitro, glasshouse and field conditions. Ocimum extract resulted in the maximum inhibition of the pathogen followed by Allium sativum and Phyllanthus extracts. T. viride showed maximum tolerance to Vitavax, Raxil and Bavistin. Integration of soil amendment (sarson cake), Bavistin (ST), Bavistin/ T. harzianum (FS) were found effective in reducing the incidence/ severity of root rot/ web blight and in increasing green pod yield. Integrated disease management by sprays of Bavistin (0.1%) on pine needle mulch alone was also quite effective to keep the disease under check besides producing near residue free pods.


Manju Choudhary (H-99-11-D)

2. Name of Major Advisor Dr. R.L.Sharma3. Title of Thesis Studies on important postharvest diseases of

tomato and their management4. Year of completion of Degree 20035. Abstract of Thesis

Four major fungi namely, Colletotrichum gloeosporioides, Fusarium spp., Geotrichum candidum and Phoma lycopersici caused 74.56 per cent of the total rots. Prevalence due to C. gloeosporioides and Sclerotium rolfsii was 4.50 and 5.96 per cent, respectively. Highest incidence of storage rots of tomato was recorded in Sirmour and Una districts followed by Hamirpur and Solan districts. Losses were maximum during rainy season which markedly decreased during October - December and January - March months. All the test pathogens could easily invade through mechanical injury, whereas infection through general surface was less. Temperature and relative humidity were correlated positive with disease incidence. None of the 27 varieties/hybrids tested was resistant to postharvest rots. Biochemical estimation revealed higher activity of cellulase (Cx) and cellobiase enzymes in S. rolfsii and by F. pallidoroseum infected tomatoes whereas, it was minimum in uninoculated tomatoes. Various fungal infections resulted in increased polyphenol oxidase and ascorbic acid oxidase enzyme activity. The increase was maximum in fruits infected with S. rolfsii. Peroxidase activity declined in variously inoculated tomatoes. The fruit qualitative characters i.e. pericarp thickness, ascorbic acid, total phenols and OD phenols had negative correlation with disease development whereas, TSS showed a positive correlation in various varieties/hybrids. Resistant varieties showed higher level of ascorbic acid and total phenols than susceptible ones. Storing tomatoes at 10-15oC caused reduction in decay and deterioration in variously inoculated tomatoes. Hydro-cooling immediately (0 h) after inoculation significantly reduced postharvest rot development in tomatoes in comparison to 24 and 48 h delayed cooling. Pre-storage heat treatment of tomatoes at 38oC for 72 h completely eliminated C. oxysporum, C. gloeosporioides and P. lycopersici and significantly checked G. candidum, F. equiseti, S. rolfsii and F. pallidoroseum. However, cent per cent control of all the test pathogens was achieved when holding period was extended to 96 h. Treating tomatoes in water at 52oC for 5 min immediately (0 h) after inoculation was effective against all the test fungi. Heated mancozeb dip in 52 and 50oC provided significant protection against all the test fungi. Bavistin impregnated liners were quite efficacious in reducing the various storage rot fungi. Indofil M-45 and Captan impregnated liners also provided fair to good control. Preharvest sprays of either Indofil M-45 or Kribenomyl, seven days before picking, were most effective in reducing the various postharvst rots and also in increasing the yield of tomatoes. Relative postharvest efficacy of Indofil M-45 ranked number one among the test fungicides. Extract of garlic cloves was effective in reducing G. candidum, C. oxysporum and S. rolfsii infections. Among the homeopathic drugs, Thuja occidentalis and Lycopodium clavatum were more efficient than Phosphorus and Kali iodide in reducing storage rots.


Renu Bala (H-99-12-D)

2. Name of Major Advisor Dr. L.N.Bhardwaj3. Title of Thesis Studies on Rhizoctonia leaf blight of strawberry4. Year of completion of Degree 20035. Abstract of Thesis

The incidence and severity of Rhizoctonia leaf blight (Rhizoctonia solani Kuhn) revealed that maximum incidence and severity (40.91 and 65.00%) were recorded at Jachh followed by Majra (40.66, 41.67%) and Jawalamukhi (38.48, 58.34%). The symptoms of disease were recorded on leaves, roots, petioles, runners and fruits. The pathogenic fungus was isolated on potato dextrose agar medium. The mycelium was initially white which later turned tan brown with age and hyphae measured 60.54 – 116.78 x 7.29-9.85 µm. Sclerotia formed within 7-10 days in culture at 25oC were brown to dark brown and measured 0.75-3.0 mm in diameter, while the monilioid cells arising from the sclerotia measured 15-38 x 10-15 µm in size. In pathogenicity tests, symptoms of the disease appeared on roots, leaves, flower buds, ripened berries and runners within 7-10 days after pathogen inoculation. Temperature (25oC), soil moisture (100%), leaf wetness duration (48 h) and intermittent leaf wetness upto 48 h were found the most critical factors for the development and spread of disease under pot culture conditions. Under field conditions, high rainfall (433.00 mm) coupled with high soil moisture (23.63%) and high relative humidity (92.50%) and moderate temperature (23-25oC) were found the most congenial factors for development of the disease. The correlation between mean temperature, average relative humidity, mean soil moisture and mean soil temperature with disease severity was positive and significant. Out of 28 strawberry cultivars screened for resistance against R. solani under artificially inoculated conditions, only two cultivars i.e. Catskill and Majestic exhibited moderately resistant reaction. Bavistin, contaf, Benlate and Punch amongst the systemic and Dithane M-45 followed by Flowin-HT among non-systemic fungicides, were found highly effective in arresting the vegetative growth under in vitro conditions. In pot culture experiments, Bavistin applied as soil drench (0.1%) + foliar spray (0.05%) was adjudged the best treatment in controlling Rhizoctonia leaf blight vis-à-vis increased the plant health. Field experiments revealed that Bavistin provided maximum disease control. Among the various organic amendments evaluated, sunflower cake gave maximum inhibitory of mycelial growth of R. solani under in vitro conditions followed by neem cake. Similarly, in pot culture and in field experiments sunflower cake was again found the best treatment in controlling and improving the plant health. Of the various plant extracts tested in vitro, maximum mycelial inhibition of R. solani was obtained with garlic extract, while in pot culture and field experiments, dip + drench treatment with garlic extract (50%) was most effective in controlling the diseases and improved the plant health. Application of black polyethylene mulch (0.05 mm thickness) + there sprays of Bavistin (0.05%) at 21 days interval was the best treatment in controlling the disease and increasing the runner production. The application of Bavistin (0.025%) + Dithane M-45 (0.2%) + sunflower cake (1 kg/pot) + garlic extract (30%) gave significant control of disease and also increased the runner production.


Chirag Singh (H-2000-2-D)

2. Name of Major Advisor Dr. T.R.Shandilya3. Title of Thesis Studies on supplementation of compost and

casing for Agaricus bisporus (Lange) Imbach4. Year of completion of Degree 20045. Abstract of Thesis

Sixteen different supplements viz., cotton seed cake, cotton seed meal, glucose, groundnut cake, groundnut meal, malt extract, molasses, mustard cake, peptone, sesame cake, sesame meal, soybean cake, soybean meal, wheat bran, wheat four and xylose were used for supplementing the compost at spawning @ 1 and 2 per cent (fresh weight basis). Amongst all the supplements used, cotton seed meal (478.0 g/3 g of compost) and sesame meal (481.7 g) when applied @ 2 per cent took significant lead in terms of yield followed by cotton seed cake (462.0 g). Mixing of selected supplements into casing layer at the time of casing gave increased yield responses in comparison to unsupplemented casing. Addition of selected supplements to ready compost at different depth levels in cropping bags have indicated that when the supplements were thoroughly mixed with the compost at spawning (@ 2%) sesame meal gave maximum yield (487.7g/3 kg of compost) followed by cotton seed meal (481.6 g) and cotton seed cake (463.7 g) as compared to unsupplemented compost (350.0 g/3 kg of compost). Regardless of supplements used, temperature of supplemented compost was found to be 1 to 1.5oC higher in comparison to unsupplemented compost from +2 days to +13 days after spawning. Highest meal percent available nitrogen was recorded in compost and casing treatments were found to be positively correlated with available nitrogen percentage. Four species of fungi viz., Mucor racemosus, Penicillium chrysogenum, Pencillium coryophilum and Rhizopus nigricans were isolated from compost supplemented with selected test supplements. Two species of bacteria i.e. Pseudomonas sp. 1 and Pseudomonas sp. 2 were isolated from all the test casing treatments. Highest population of containing fungi, irrespective of fungal species, appeared in compost supplemented with cotton seed cake (31.20 x 104 cfu/g of compost). Highest average bacterial population was observed in sesame meal supplanted casing (106 x 104 cfu/g of casing soil).


Gyatri Bhardwaj (H-2000-1-D)

2. Name of Major Advisor Dr. C.L.Jandaik3. Title of Thesis Studies on Calocybe indica (P. &C.) the milky

mushroom4. Year of completion of Degree 20045. Abstract of Thesis

During the present investigation, an attempt was carried out to standardize the cultivation technology of milky mushroom (Calocybe indica). The evaluation of most suitable temperature for mycelial growth revealed 30oC as the optimum temperature for full and fast mycelial impregnation us substrate by C. indica. Mother culture of C. indica inoculated on wheat grains, kept at 30oC for 15 days produced the best quality spawn. Fresh spawn mixed in steam pasteurized wheat straw at 4 per cent spawn density, with through spawning method at 35oC cropping temperature produced dense white fluffy mycelium that lead to healthy sporophore production of C. indica. Loam soil proved to be the best casing material. The incidence of moulds like Trichoderma harzianum and Papulaspora byssina was recorded. The application of carbendazim and benomyl at 50 ppm effectively controlled these moulds. Cobweb disease caused by Cladobotryum dendroides was also recorded. Carbendazim and benomyl at 50 ppm could control the disease effectively.


Brijesh Kumar Kamal (H-99-10-D)

2. Name of Major Advisor Dr. A. K. Gupta3. Title of Thesis Studies on crown gall of cherry and its

management4. Year of completion of Degree 20045. Abstract of Thesis

Cherry (Prunus avium and P. cerasus) is highly susceptible to crown gall caused by Agrobacterium tumefaciens. Its incidence ranged from 3.70 to 100 per cent during 2001-2002 in different nurseries in Himachal Pradesh. Crown gall infected cherry rootstock- Colt suckers showed reduction in growth, maximum in chlorophyll contents (44.91%). All the isolates of A. tumefaciens from galls of infected plants and infested soil belonged to biovar-1. Grafting of scions of cherry cv. Van, Merchant, Deuro-Neuro and Pietro-Nigra resulted in minimum incidence (4 %) as compared to un-grafted (24.40%). Amendment of crown gall infested soil with mustard cake @ 1.5 per cent reduced the incidence (11.50%) as compared to control (55.72%). Soil sterilization with formaldehyde (4 %) also resulted in minimum incidence of crown gall (9.77%) as compared to control (53.25%). Pre-plant application of oxyfluorefen (0.5 L/ha) also reduced the incidence by 50 per cent. Application of copper sulphate (1%) as root dip treatment of healthy one- year old Colt suckers at the time of planting reduced the incidence of crown gall (30.17 %) as compared to control (77.31 %). Soil solarization for 90 days of irrigated sick plots with 25µm thick transparent polyethylene sheet also minimized incidence (16.21%) as compared to non-solarized control (51.94%). Amongst different rhizosphere micro-flora from healthy and crown gall infected plants, application of Bacillus sp, Pseudomonas fluorescens and Trichoderma viride as soil drench (4 L/m2

containing 108 CFU-ml) resulted in 5.45, 5.80 and 12.73 per cent incidence, respectively as compared to control (25.83%). The combined effect of all the efficacious treatments viz., soil solarization (90 days), pre-plant application of formaldehyde (4 %), oxyfluorfen (0.5 L/ha) and Bacillus sp.; amendment of soil with mustard cake (1.5 %) and copper sulphate (1%) as root dip reduced the incidence (24.70%) as compared to control (69.75%).


Manica Tomar (H-97-15-D)

2. Name of Major Advisor Dr. R.C.Sharma3. Title of Thesis Studies on the management of Fusarium root rot

of Acacia catachu Willd.4. Year of completion of Degree 20045. Abstract of Thesis

Investigations on Fusarium root rot of Acacia catechu were undertaken to identify the fungal species associated with the disease, factors affecting development and spread of the disease and management through cultural, biological and chemical means. The studies revealed that the fungus causing root rot is Fusarium solani. The fungus in soil survived best on 50-60 per cent available soil moisture. The optimum soil temperature for the development and spread of the fungus was found to be 30oC. The temperature range between 25-30oC also favoured the development and spread of the disease. The soil solarization done during March to June using 25 and 50 micrometer thickness polythene mulches for 45 and 60 days revealed that lowest root rot incidence occurred in those plots which were solarized from April 15 to June 15 for 60 days under 25micrometer thickness polythene mulch. Out of the various organic amendments tested against Fusarium root rot, neem cake and cotton seed cake gave the best results. The application of different doses of NPK revealed that higher nitrogen doses favoured the disease while the higher potassium dose had negative effect on the disease. Combination of potassium @ 30 kg/ha and cotton seed cake @ 5 per cent proved to be effective against root rot of A.catechu. Among the various antagonists studied under in vitro conditions, Trichoderma viride gave maximum mycelial inhibition. Amongst all the plant extracts tested, Allium sativum gave the best results. Bavistin showed maximum inhibition of mycelium under in vitro conditions while under field conditions, the combination of Bavistin and Dithane M-45 gave the lowest root rot incidence.


Shyama Nand Sharma (H-2001-11-D)

2. Name of Major Advisor Dr. Ved Ram3. Title of Thesis Studies on biological control of major cankers of

apple4. Year of completion of Degree 20055. Abstract of Thesis

Trichoderma viride, T. longibrachiatum, T. harzianum, T. hamatum, T. polysporum and Fusarium lateritium proved highly effective under in vitro conditions against Corticium salmonicolor, Sphaeropsis malorum and Dothiorella mali. The malt extract agar and potato dextrose agar in semi-synthetic, modified Richard’s agar and modified Czapek Dox agar in synthetic media categories, supported maximum growth and sporulation of all antagonists. With regard to temperature (25oC) and pH (6.5 ) were found optimum with suitable ranges of 20-30oC and 5-7, respectively. Amongst the pesticides, propineb, mancozeb, copper oxychloride in fungicide and dimethoate, malathion and endosulfan in insecticide categories, were found compatible with antagonists. Aonla, dodonia and citronella grass among plant oils were found effective against canker pathogens at different concentrations. In the timings of application of antagonists, pre-inoculation was found superior to post-inoculation. While in methods of application, malt extract slurry was observed highly efficacious than the spore suspension in combating canker development. In the integrated control, copper oxychloride followed by mancozeb in combinations with T.viride and/or T. longibrachiatum were found highly effective against canker disease.


Promil Kapoor (H-2001-22-D)

2. Name of Major Advisor Dr. P.D.Thakur3. Title of Thesis Investigations on the viruses infecting bell pepper

(Capsicum annuum L.)4. Year of completion of Degree 20055. Abstract of Thesis

The virus incidence ranged from 1 to 100 per cent in different bell pepper growing districts of the state during 2003 and 2004 cropping seasons. Thirty geographical isolates were categorized into two distinct groups of potyvirus and cucumovirus based on their serological relationships and reactions on set of indicator plants. Two representative isolates (C-I and C-II) from each group were further characterized and identified. Isolate C-I exhibited symptoms of vein clearing, mottling and stunting, whereas C-II isolate produced mosaic and ringspot on leaves. Both the isolates were transmissible through sap and aphid vector Myzus persicae. Isolate C-I infected test plants namely Gomphrena globosa, Calendula officinalis and Zinnia elegans; Brassica oleraceae var. botrytis; Datura metel, D. metel var. festuosa, D. stramonium, Nicotiana tabacum var. White Burley, Petunia hybrida, Solanum tuberosum and Solanum nigrum; and Phaseolus vulgaris, Vicia faba and Vigna unguiculata whereas C-II infected test plants viz., Amaranthus caudatus; Calendula officinalis; Cucumis sativus and Cucurbita pepo; Datura metel, D. stramonium, Physalis floridana and Phaseolus vulgaris and Vigna unguiculata. Biophysical properties of C-I and C-II isolates included TIP of 65-70oC and 60-65oC, DEP of 10-4 – 10-5 and 10-5 – 10-6 and LIV of 6-7 and 5-6 days at room temperature, and 7-8 and 8-9 days under refrigeration, respectively. Isolates C-I and C-II had flexuous rods measure 760 x 11 nm and isometric particles of 28.5 nm, respectively. C-I isolate produced cylindrical inclusions (pinwheels, scrolls, tube and laminated aggregates) in the cytoplasm, whereas no specific inclusion bodies were observed in C-II isolate. ISEM studies showed good clumping of C-I and C-II isolate with PVMV and CMV antisera, respectively. Serologically, C-I isolate also showed relationship with PVMV and C-II isolate with CMV in DAC and DAS-ELISA tests. C-I isolate was detected in RT-PCR assay by using potyvirus specific primers (P9502 and CPUP). C-I and C-II isolates have been identified to be the strains of PVMV and CMV, respectively. Weeds namely, Physalis minima, Nicandra physaloides, Solanum nigrum, Datura stramonium, D. metel var. festuosa were found to act as potential reservoirs of PVMV. Early plantation in first fortnight of May, plant spacing of 50 x 50 cm, use of silver or white coloured polythene mulches, and maize as a barrier crop were found effective in reducing disease incidence and obtaining maximum yield. Aqueous leaf extracts of Mirabilis jalapa and Asparagus adcendens were found effective in inhibiting the transmission of PVMV under glasshouse conditions. None of varieties/collections/lines of bell pepper and paprika tested were resistant, but chilli collections namely Chilli Pragathi, DK-32, DK-6B, DKC-14, DKC-7B and DKC-8 were highly resistant to the virus infection under field conditions.

Name of Student: Anil KumarAdmission No. : H-07-13DName of Major Advisor: Dr J.N. SharmaYear of completion of degree: 2011Title of Thesis: Studies on epidemiology and monitored control of Marssonina blotch

causing premature leaf fall in appleAbstract :

The present investigation to study the influence of different weather parameters and comparative physical mode of action of different fungicides against Marssonina blotch causing premature leaf fall in apple. Experiments were conducted under controlled, semi-controlled and natural conditions to find out the optimum temperature, relative humidity and leaf wetness requirements for the development of Marssonina blotch disease. A temperature of 20oC, 100 per cent relative humidity and 48 h of leaf wetness were the most suitable parameters for the development of Marssonina blotch disease in apple. Rainfall, leaf wetness, and relative humidity were positively correlated with disease severity, whereas, temperature showed a negative correlation. The coefficient of multiple determination was also calculated which signifies that 91.61 and 97.03 per cent variation in per cent disease severity in year 2009 and 2010, respectively, depended on weather parameters included in these studies. Further studies revealed that none of the cultivars of apple was resistant to Marssonina blotch, however, Granny Smith and Gibbson's Golden showed moderately resistant reaction. The commercial cultivars Royal Delicious, Golden Delicious, Vance Delicious and Scarlet Spur were found highly susceptible. Older leaves of apple plants were more susceptible to Marssonina blotch than the younger ones. The macronutrient combinations with full dose of nitrogen registered good growth of apple plants and reduced the severity of Marssonina blotch. Different isolates of Marssonina coronaria showed different levels of disease severity and conidial production indicating a genetic variability in the pathogen. Fifteen different fungicides, viz. mancozeb, captan, dodine, copper oxychloride, metiram, benomyl, carbendazim, thiophanate methyl, shield, Kresoxim methyl, azoxystrobin, pyraclostrobin, hexaconazole, difenoconazole and tebuconazole were evaluated at different concentrations for their physical mode of action. Whereas, nine fungicides, viz. mancozeb, kresoxim methyl, carbendazim, difenoconazole, metiram, thiophanate methyl, dodine, shield and pyraclostrobin+metiram were selected for such study in the field. Dithiocarbamate fungicides provided maximum control of Marssonina blotch disease with more effect on conidial production, germinability and viability after their protective applications on apple plants both under semi-controlled as well as under field conditions. Mancozeb formulations also showed maximum retention activity as compare to other fungicides, and, registered maximum control of the disease. Strobilurin fungicides showed the strongest curative, pre-symptom and post-symptom activity against Marssonina blotch in semi-controlled as well as under field conditions. These fungicides showed inhibitory effect on conidial production, germinability and number of viable conidia as compared to other test fungicides. On the basis of prophylactic rating, dithiocarbamate fungicides were most effective protectants against Marssonina blotch of apple. The after-infection, pre-symptom and post-symptom activity of strobilurins, benzimidazoles and triazoles exceeded that of their protective activity. Strobilurin fungicides were rated best (with 1-3 rating) followed by the benzimidazoles in this respect. In field, pyraclostrobin+metiram attained the highest rating (1) followed by

kresoxim methyl, carbendazim, thiophanate methyl, dodine, difenoconazole, mancozeb, shield and metiram. Among six spray schedules evaluated in field, spray schedule-II (comprising of mancozeb (0.3%) at walnut stage, carbendazim (0.05%) at 20 days after 1st

spray and mancozeb flowable (0.3%) at 40 days after 2nd spray) was found best to control Marssonina blotch of apple, along with directed sprays of kresoxim methyl in monitored spray programme.

Phd Abstracts India-Microbiology

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