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A review on Alternaria leaf blight of carrot

Muhammad Mubashar Zafar1*, Hina Firdous2 and Muhammad Saqib Mushtaq2

1Department of Plant Breeding and Genetics, University of Agriculture, Faisalabad, Pakistan.

2Department of Plant Pathology, University of Agriculture, Faisalabad, Pakistan.

*Corresponding author’s email: m.mubasharzafar@gmail.com

Volume: 1 Issue: 1

Received: 2018-10-12 Accepted: 2018-11-07, Published: 2018-11-08

Abstract

Carrot is an important vegetable root having great health, medicinal and nutritional importance.

Carrot (Dacus carota) belongs to family Apiaceae, order Umbellifera. Genus Dacus consists of 25

species. Carrot is a perennial plant having a long conical edible root. It is utilized as serving of

mixed greens, steamed or bubbled in vegetables and may likewise be set up with different

vegetables to get ready soup and stew. Carrot is defenseless to numerous bug vermin and

infections. Carrot crop is influenced by bacterial, viral and parasitic illnesses yet among contagious

ailments Alternaria leaf blight (Alternaria dauci) is real constraining development consider that

causes substantial financial misfortune. Among the disease, Alternaria blight of carrot is the

devastating disease of carrot in which leaves are rapidly killed upon infection. This disease if left

unchecked spreads rapidly and may progress to form an epidemic (epiphytotic). Alternaria dauci

is the pathogen which is commonly supported by direct to warm temperature. Time of long wetness

is extremely fundamental for the germination of contagious spore on the carrot crop. The climatic

conditions for the great generation of this product are 15-20˚C temperature, relative humidity

>50% all through the development season and soil PH of 6, But the climatic conditions for the

contamination advancement because of Alternaria dauci on carrot crop are 20-25˚C temperature,

relative humidity >60% and soil pH of 6-6.5. Great loses occur when the plant is contaminated by

Alternaria dauci amid direct temperature, confronting long relative moistness period because of

dew, precipitation and sprinkler water system. As pathogen is basically presented in the plantings

through seeds so one of the best preventive measure is the utilization of treated or ailment free

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seeds. Resistance germplasm is additionally an essential source that confines its spread. Sowing

of safe carrot cultivars is a significant way to deal with this disorder of carrot at business level.

Proper forecasting of disease along with the use of resistant varieties and post-infection treatment

of chemicals and plant extracts is favorable for the proper management of Alternaria blight of

carrot.

Key words: Alternaria leaf blight (ALB), carrot, biological control

Introduction

Carrot (Daucus carota L.) is an essential vegetable crop in Pakistan and also in the world. The

carrot has been known since long time prior in this century so it is trusted that this crop was begun

from the Afghanistan and its neighboring ranges before 900s (Gugino et al., 2004). Carrot is a

standout amongst the most vital vegetable product that gives great dietary incentive in everywhere

throughout the world (Rubatzky, 2002). The cultivated area of carrot is one million hectares on

the earth with the yearly production of 27 million tons yet in Pakistan it is grown on 13.9 thousand

hectares with the yearly production of 242.3 thousand tones (FAO, 2008). The national normal

yield of this harvest is sensibly low when contrasted with other dynamic nations, for example,

Belgium (47.64 tons ha-1), Denmark (44.29 tons ha-1) and the United Kingdom (44.28 tons ha-

1). In Africa and South America carrot production expanded gradually when however in Asia

(basically china) it expanded at extremely fast rate particularly in 1997 to declare Europe as a main

creation region (FAO, 2008).

The variety Daucus contains 25 species and is biggest class of the family umbelliferea. Its

name is taken from a French word ˝carotte˝, which originated from the Latin word ˝carota˝ that

implies a lasting plant which is broadly developed because of its long funnel shaped orange

consumable root (Northolt et al., 2004). It has a place with the Apiaceae family and has sixteenth

position when contrasted with different families. It is evaluated that it has more than 3700 species

which constitute around 434 genera (Suojala, 2000). It is utilized as serving of mixed greens,

steamed or bubbled in vegetables and may likewise be set up with different vegetables to get ready

soup and stew (Anjum and Amjad, 2002).

Carrot is a cool season crop and grown under the temperature scope of 10-25˚C in light of

the fact that it gives better production under this temperature. It is demonstrated that the ideal

temperature of day and night for plant development is 25°C and 20°C, separately (Alam et al.,

2004). The seedlings of carrot bear ice and the temperature of - 7˚C however the top development

is influenced by underneath 4˚C, and this serious condition will cause the death of plant. Carrot is

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the piece of human eating routine. It contains carotene and a forerunner of Vitamin A (Zeb and

Mahmood, 2004). Carrot likewise has helpful impacts that lessening the eyes and blood illness

(Pant and Manandhar, 2007). The taproot of the carrot harvest is the consumable segment and

valuable for the wellness, as per the review, the examination of the eating methodologies of 1,300

develop people in Massachusetts began that individuals who had no less than one serving of squash

or carrots consistently had 60 percent diminishing in their danger of heart assaults connected to

the individuals who ate less than one serving of carotenoid rich sustenance every day. Over

adhering to a good diet conspire on the planet has constrained the general population to expend

additional crisp foods grown from the ground (Rubatsky, 1999).

Carrot crop is influenced by bacterial, viral and parasitic illnesses yet among contagious

ailments Alternaria leaf blight (Alternaria dauci) is real constraining development consider that

causes substantial financial misfortune (Koike et al., 2009). This infection happens toward the

finish of January when temperature is 24˚C (Farrar et al., 2004). Alternaria dauci is the significant

reason for this ailment which is a seed born parasite and is a genuine risk to production of carrot

yield (Rogers et al., 2011). The characteristic symptoms of this disease is the production of lesions

which are green to darker in color that at long last wind up plainly necrotic following 8-10 days of

contamination. Injuries show up on the leaflets and petioles of carrot plant as lesions with a yellow

hallo. Leaves end up plainly yellow, crumple and become dead when 40% leaf region ends up

noticeably contaminated by this pathogen. Because of these indications, rate of photosynthesis

decreased which diminishes the root measure (Pryor et al, 2002).

Great loses occur when the plant is contaminated by Alternaria dauci amid direct

temperature, confronting long relative moistness period because of dew, precipitation and sprinkler

water system. No measurements accessible for yearly production loses because of Alternaria dauci

disease in carrot crop, however in Israel serious damage to this crop have been accounted for to

cause the decrease of yields by 40-60% (Ben et al., 2001).

Sexual multiplication of this pathogen is as yet obscure along these lines, it reproduce

asexually by delivering conidia on erect conidiophores. The essential inoculum of this pathogen is

plant trash and pathogen overwinters in the plant debris. Conidia attach on the leaf surface and

sprout under favourable condition. At 24˚C with expanding hours of relative humidity from 8-56

hours damage increases (Dugdale et al., 1993). Germ tubes are delivered on conidium, which

specifically enter to the host cell divider to set up disease site and create phytotoxin Zinniol, which

degrade the cell membrane structure and chloroplast (Pryor and Strandberg, 2002). At the time of

colony formation leaf cells neighboring mycelium misfortune chlorophyll and end up noticeably

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yellow. Following 8-10 days of disease conidia will sprout once more. By revising a similar

procedure life cycle is finished (Ben et al., 2001).

Alternaria dauci is the pathogen which is commonly supported by direct to warm

temperature. Time of long wetness is extremely fundamental for the germination of contagious

spore on the carrot crop. At the point when temperature builds the period of wetness decreases

which is required for the leaf disease. Contamination will happen in 8-12 hours of temperature

range of 16-25ºC. At the point when Alternaria dauci will encounter this temperature go, it

sporulates promptly on necrotic tissues of the carrot leaf and spore will grow in water beads and

dew (Gugino et al., 2004).

Carrot is a cool season crop. Disease because of Alternaria dauci will be built up when

there will be ideal ecological conditions for the pathogen to sporulate. The climatic conditions for

the great generation of this product are 15-20˚C temperature, relative humidity >50% all through

the development season and soil PH of 6, But the climatic conditions for the contamination

advancement because of Alternaria dauci on carrot crop are 20-25˚C temperature, relative

humidity >60% and soil pH of 6-6.5 (Joubert et al., 2000).

There are a few approaches to deal with this disease. As pathogen is basically presented in

the plantings through seeds so one of the best preventive measure is the utilization of treated or

ailment free seeds (Farrar et al., 2004). With a specific end goal to lessen the inoculum level, seed

ought to be dealt with by heated water treatment or fungicides, for example, azoxystrobin,

iprodione, fludioxonil and thiram (Strandberg, 1988). Seed treatment is not the full destruction of

applicable pathogen (Farrar et al., 2004). Crop rotation is basic for constraining the contamination

in carrot against Alternaria dauci. Pivot ought to be sufficiently long to disintegrate the plant debris

(Pryor et al., 2002).

Resistance germplasm is additionally an essential source that confines its spread (Boedo et

al., 2010). Sowing of safe carrot cultivars is a significant way to deal with this disorder of carrot

at business level. As advancement of safe cultivars through rearing is tedious process so field

screening is done to locate the safe cultivar. Despite the fact that field screening has a few obstacles

because of ecological variables however it likewise favored over different strategies because of its

simplicity (Pawelec et al., 2006). Without safe carrot cultivar, other technique to control this

infection is the utilization of appropriate fungicide. Diverse sorts of fungicides are utilized to

control this illness as indicated by infection edge level, date-book timetable and estimating

framework (Langston and Hudgins, 2002). In Pakistan, Azoxystrobin and pyraclostrobin

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demonstrated astounding outcomes in the administration of this infection (Hausbeck and Harlan,

2003).

Same pattern of cropping is bad for soil health that outcomes in the inadequacy of

fundamental minerals and supplements when contrasted with those dirts having crop rotation

(Zhou and Zhao, 2011). So adequate accessibility of supplements in the dirt is fundamental for

good product wellbeing and yield. Phosphorus is useful to plants to expand their number of

branches and leaves (Zhang et al., 2004). Also nitrogen is vital piece of protein, nucleic acid and

chlorophyll and it assumes a noteworthy part in vegetative development of plants (Viradia and

Singh, 2004). Calcium is in charge of the abiotic issue of item to expand advertise values (Chang,

2002). Inadequacy of any fundamental component in the dirt outcomes in the generation

misfortunes. Resistance of yield additionally increases by the foliar use of supplements so it

diminishes the Alternaria leaf curse infection seriousness (Kashif et al., 2005). This is likewise

useful to limit the postharvest loses and conidial germination (Yildirim et al., 2002).

REVIEW OF LITERATURE

History and Symptomology of the Disease

Alternaria leaf blight of carrot caused by a growth Alternaria dauci. It has a place with

pleosporaceae group of ascomycetes (Kuhn, 1944). It is an essential foliar disorder of vegetables

in south Asia. This sickness was accounted for in various nations and contemplated by various

researchers like United States, in Louisiana in 1890 (Ellis et al., 1972)Hatay area of Turkey in

November 2003 (Soylu et al., 2005), Germany in 1855 (Pryor and Strandberg, 2002) and in

Pakistan (Kuhn, 1944). The seriousness of this illness come to 80% contingent on ecological

conditions and treatment rate (Ben et al., 2001). Parasites having a place with sort Alternaria

comprise of extensive variety of pathogens in charge of causing tremendous yield and monetary

loss in field, natural product, vegetables and decorative harvests (Strandberg 1992, Farrar et al.,

2004).

Characteristic symptoms of this infection are greenish-dark colored sores on petioles and

appendages. In preliminary stages these sores are unpredictable fit as a fiddle and size which are

normally shaped along the edge of handout. With the progression of time these injuries move

toward becoming water soaked. More seasoned injuries end up noticeably dim dark colored and

encompassed by chlorotic corona. At temperature of 28˚C with long wetness period prompts

contamination improvement and injuries turn into various, extend and combine, giving the cursed

appearance to the leaf tissue (Strandberg, 1984). Pathogen executes the leaves by supporting

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petioles, in this manner significantly decreasing the photosynthetic action (Farrar et al., 2004).

Right off the bat, sores show up on leaves and petioles and following 8-10 days of disease it

assaults on more established leaves in light of the fact that these are more vulnerable to

contamination. At the point when 40% of the leaf winds up noticeably contaminated it ends up

plainly yellow fall and damage. Good natural condition for the disorder improvement make the

whole finish of the plant cease to exist, a marvel in which at some point mistaken for ice harm

(Schwartz et al., 2016). The injuries created by Alternaria dauci are unpredictable fit as a fiddle

having dark colored to dark shading and generally shows up on the edges and tips of the develop

leaves of the carrot plant (Farrar et al., 2004; Hooker, 1944; Strandberg, 1992).

reported that Alternaria spp. is responsible for causing damping-off of carrot seedlings but

when there is over-crowding of carrot foliage it creates a humid environment which makes the

conditions favorable for the development of pathogen thus causing serious infection to the foliage.

Soteros (1979) and Mitakkakis et al. (2001) reported that Alternaria dauci and Alternaria

radiana are threatening pathogens of carrot causing severe foliage infection to carrot plant by

attacking all the plant parts including flowers, leaves, stem and seedling.

Characterization of pathogen

Meier et al. (1922) reported that Alternaria dauci reproduces asexually with the help of conidia

and these conidia are produced in a single phase or in the form of a short chain, displaying light to

dark olive brown color with clavate, ellipsoid, obovoid or turbinate in shape. Conidia ranges

between 34-51 × 10-22µm, mycelium shows 3-8 transverse septation along with one or more

longitudinal septation which causes the division of one or all segments may not be the apical or

basal cells showing compression at the segmentation.

Groves and Skolko (1944) described that A. dauci produces smooth walled hyphae having

a size of 15-30 × 25µm and are colorless pale to dark brown in color. Origin of conidiophores is

in the form of small groups which are may be erect or flexible and sometimes geniculate,

segmented. Conidiophores are pale to olive brown in color ranging in size from 80 × 6-10µm.

Conidia are produced in the form of chains. At immature stage, conidia have smooth wall, straight

curved, obclavate having 7-11 septa which may be transverse, longitudinal or oblique. It ranges in

size from 100-450 × 16-25µm. These conidia have a hyaline, flexuous beak which is about three

times large in length as compared to the main spore body.

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Zimmer and McKean (1968) described that Alternaria dauci liberates the spores at a

maximum pace when the temperature ranges between 15-27oC along with the long wave cool

white fluorescent radiation to ultraviolet radiation photoperiod. On the electromagnetic spectrum,

the ultraviolet radiation excites the production of conidiophores. At the temperature of 24oC.

Roy (1969) determined the pathogenicity of Alternaria dauci on the carrot seedlings grown

in earthen pots as well as detached plants grown in water contained conical flasks. Infection of

Alternaria blight was observed after 3 days of inoculation. The virulence of the pathogen was at

its higher note where humidity was persisted for 72 hours and this intensity was decreased

considerably at 48 hours and 24 hours. On young carrot plants small necrotic spots are produced

along with after six days.

Ellis and Holiday (1972) described the morphology of Alternaria dauci as it produces

septate hypha which is 2-7.5µm in width, which later forms grayish or bluish black mycelia. A.

dauci reproduces asexually by conidia which are produced on the tip of conidiophores. These

conidiophores are 200µm long and 3-9µm wide, mostly unbranched, segmented and erect, flexible

showing pale to olive brown in color.

Ellis and Holliday (1972) also found that Alternaria radicina develops brownish black

color mycelial growth on potato dextrose agar (PDA) media.

Pyror et al. (1998) concluded that Alternaria radicina grows on a specific media called A.

radicina selective media (ARSA).

Pyror and Gilberton (2002) also found that fungus develop mycelium with irregular

margins showing a yellow colored stain on the culture medium and didentric crystal on the petri

dish.

Soylu et al. (2005) described that Alternaria dauci produces a velvety mycelial mat having

reddish brown color on potato dextrose agar media.

Soylu et al. (2005) also assessed the pathogenic behavior of Alternaria dauci on carrot

seedlings of six leaf stage by the spray of A. dauci using a conidial suspension at 1 × 104 spores/mL.

The inoculated plants were covered with polyethene bags placed in incubator at 26oC for 2 days

which then subsequently transferred to growth cabinet at 26oC having 16 hour photoperiod. After

10 days of incubation, symptoms of Alternaria blight were appeared on the plants.

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Mode of spread and survival

With the recent advances in agricultural technology, weather is an important factor which may

cause substantial yield losses (Harrison, 1992). Climate and weather both are important factors

which makes the plants susceptible to the attack of pathogen. Weather includes temperature,

rainfall, humidity, radiation, wind velocity, wind direction, cloud coverage and atmospheric

pressure. These factors contribute towards the development of epiphytotic (Pathak and Singh 1988,

Raposo et al., 1993, Johar et al., 1997, Sunseri and Johnson, 1999).

Luckens (1960) described that with the changes in the periods of lightness and darkness

conidiophore are developed and increased duration and intensity of light determines the number

and size of spores.

Gupta and Nikhanj (1972) at pH level of 6, light intensity favor the production and

multiplication of spores while at pH 7, temperature around 22.5oC was found best for the

germination of Alternaria spp.

Bashi and Rotem (1975) compared the increased and reduced time of leaf wetting for the

development of Alternaria blight and it was concluded that leaf wetness of 24 hours with 12 hours

of light and 12 hours of dark increased the sporulation capability of fungus. The sporulation rate

was decreased to few or none when the lightness and darkness in combination were reduced from

24 hours.

Waggoner and Parlang (1975) discovered that the temperature between 16-35oC the spore

germination of Alternaria spp. increases at a rapid pace.

Madden et al. (1978) predicted that Alternaria blight of tomato is being favored by

temperature and leaf wetness and under the prolonged favorable conditions the severity increases

up to its maximum level.

Kadian and Saharan (1984) reported that on mustard plant, minimum 4 hours of leaf

wetness are essential for the disease development. Longer leaf wetness period increased the rate

of infection on leaves.

Strandberg (1988) concluded that temperature range of 20-28oC with optimum temperature

of 24oC along with increased time period of leaf wetness favors heavily for the in-vivo

development of Alternaria blight of carrot. Furthermore, Alternaria dauci showed virulence on

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carrot plants at 4-6 leaf stage and conditions favorable for the development are 16-28oC with 100%

relative humidity and prolonged wetness on the leaf.

Pelletier and Fry (1989) concluded that infection rate of Alternaria solani increases on

potato crop with an increase in leaf wetness period from 6 to 24 hours.

The fungus is both seed and soil-borne. For the spread of primary inoculum, the diseased

seed plays a vital role in the development and spread to remote areas (Maude 1966, Netzer and

Kenneth 1969, Scott and Wenham 1973, Soteros 1979, Standberg

1983). During the wet and cold conditions seed infection was found to be more virulent as

compared to dry and warm conditions (Tylkowska 1992).

Rottem (1994) described that temperature and leaf wetness are the major contributors for

increasing the severity of Alternaria spp.

Hong and Fit (1996) that temperature of 20oC along with leaf wetness of 4-24 hours tends

to increase the disease incidence.

Rubatzky et al. (1999) reported that maximum temperature of 35oC and minimum

temperature of 14oC and optimum temperature is 27oC which greatly favors the development of

Alternaria dauci.

.Vloutoglou and Kalogerakis (1999) explained that the leaf wetness period from 4 to 6

hours after the infection of fungus is satisfactory for the development of disease on plants. With

every 24 hours increase in leaf wetness, the leaf area under infection also increased and that area

become defoliated.

Vloutoglou and Kalogerakis (2000) also found that level of inoculum, leaf wetness time

period and age of plant showed significant relationship with host susceptibility controlled

environment conditions. Pre-mature leaf defoliation showed direct response with leaf infected

area. With an increase in the concentration of inoculum the rate of leaf defoliation also increased.

Westerveld et al. (2002) explained that running water, splashed rain and infected soil are

the main reservoirs of fungal spores and through these reservoirs spread of fungal spores occurs.

During unfavorable conditions infection rate becomes slow.

Farrar et al. (2004) described the fungus as it produces conidia on conidiophores under the

temperature range from 8-28oC with 96-100% relative humidity or increased leaf wetness. Leaf

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wetness ranging from 8-56 hours along with optimum temperature of 24oC also favors the

increased severity of A. dauci.

Shrestha et al. (2005) concluded that on tomato crop, Alternaria solani infects greatly at

maximum temperature of 18-25oC, minimum temperature of 10-14oC, relative humidity of 80-

90% and leaf wetness of 14-15 hours.

Saude and Hausbeck (2006) that the environmental conditions which makes the pathogen

favorable to attack are 20oC temperature and 96% relative humidity.

Manjunath et al. (2010) tested the impact of various levels of pH, temperature, light

intensity and culture media on the growth and development of Alternaria spp. under controlled

conditions and the results of this experiment concluded that the growth of Alternaria spp. was at

its peak at the temperature of 25-30oC, pH of 6-6.5, 12 hours of lightness and 12 hours of darkness

with repetitions and potato dextrose media was the best for the growth and clear observation of

Alternaria spp.

The rate at which the pathogen spreads mainly depends upon initial inoculum level, air

temperature, leaf wetness time and susceptibility of host plant (Aguilar et al., 1986; Carisse and

Kushalappa, 1990; Gillespie and Sutton, 1979; Pryor, 2002). Petiole contamination can happen

with no sore advancement on leaves and Alternaria dauci can furthermore brings about damping-

off of seedlings, seed stalk curse and inflorescence diseases. The ailment is dynamic amid spring,

summer and harvest time editing cycles. The infection cycle starts when growth overwinters on or

in host seed and in plant debris (Koike et al., 2009).

Alternaria dauci likewise spread into field by means of degraded carrot seeds amid

development. Once presented, the pathogen can persevere in carrot plant debris or polluted seeds

in the dirt for up to two years. Temperature ranging from 20-28oC or optimum temperature of 24oC

along with prolonged leaf wetness helps to develop infection and thus infection is promoted. The

lesions increase in number which merges and enlarges to from foliar blight and it also causes

petiole girdling. Alternaria dauci can also be transmitted through infected or filthy seed (Carisse

and Kushalappa, 1990, 1992; Hooker, 1944; Langenberg et al., 1977; Strandberg, 1988).

Seedling contamination happens close to the hypocotyl-root intersection (just beneath the

dirt line) at that point in the early spring taking after overwintering of pathogen mycelium or

conidia (Rogers et al., 2011). This contaminated area will end up plainly necrotic and prompt the

generation of more abiogenetic conidia on conidiophores which fill in as secondary inoculum.

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Wind and rain make conidia scatter to neighboring host species and various germination tubes will

be delivered from every conidium that effectively colonizes another host. As entrance happens,

Alternaria dauci creates a compound known as phytotoxin zinniol, which corrupts cell layer and

chloroplast, at last prompting the chlorotic side effects normal for the infection (Farrar et al., 2004).

The germination tube penetrates the host cell divider to start contamination that declines the

nutritive estimation of vegetables, their storability and imperviousness to decays (Coles and

Wicks, 2003). Their polyphagous nature and capacity to deliver mycotoxins and other harmful

metabolites imply that they are possibly perilous sustenance waste specialists (Solfrizzo et al.,

2005).

Histopathological studies reveal that fungal mycelium resides inside the pericarp or in testa

of the seed but does not penetrate inside embryo or endosperm (Pyror, 2002). Kim and Mathur

(2006) reported that pathogen further penetrates inside the endosperm or fused seed coat. During

the germination of seed, the spores of A. dauci infects young seedlings of carrot plant and creates

black necrotic region on the root and shoots leading to deformation of the plant and in severe cases

the death of the seedling. Infection of A. dauci on the roots occurs through damaged or non-

damaged root tissues but more infection was observed on the damaged roots of the plant (Merfield,

2009). Initial infection on the root portion of the plant creates a black ring on the petiole and root

junction which forms a dark, longitudinal spots on flower stalks and umbels. These infected

umbels unable to produce a new seed (Farrar et al., 2004).

Management

Fry (1982) described that resistant cultivar can reduce the onset of disease, symptoms development

and slow the rate of epidemic development.

Acceptance of resistance in plant against pathogen prompted the actuation of guard

qualities that were powerless under typical conditions (Kushalappa and Gunnaiah, 2013).

Utilization of safe assortments was the most proficient and savvy technique (Gugino et al., 2007).

For the determination of safe source, screening of accessible germplasm was the essential.

Roy (1969) evaluated 11 varieties of carrot against Alternaria leaf blight disease. The

varieties evaluated were early nantes, nantes, amsterdam forcing, champion scarlet horn, long

orange, early gem, danvers, fyazabad, golden heart, imperator and tender sweet. The results

concluded that all varieties showed susceptible response against Alternaria leaf blight disease.

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Simon et al. (1998) screened out three cultivars of carrot i.e. Presto, Bolero and B-5280

against Alternaria dauci. The results concluded that Presto showed highly susceptible response

while Bolero and B-5280 showed moderately resistant response against Alternaria leaf blight

disease.

Gugino et al. (2007) tested 8 varieties of carrot i.e. ithaca, fullback, kamaran, napa, nevis,

white fontana, carson and neal. The results concluded that ithaca and fullback showed moderately

susceptible response. Kamaran, napa and nevis showed susceptible response and white Fontana

was the highly susceptible variety found in the experiment as compared to all varieties.

In an exploratory field of the NYSAES Vegetable Research Farm in Geneva, NY, 19, 21,

10, 5, and 3 business cutting and dicing carrot cultivars were planted in 1999-2003, and checked

for the advancement of leaf blight indications. Plots of every cultivar comprised of four 3m long

lines. Each plant was reproduced by 5 times (1999-2002) under Randomize finish square outline

(RCBD). Each pot and line was lined by powerless cultivar "Hawk" and tainted by inoculum of

Altenaria leaf blight. From 2000-2003 just cercospora leaf blight happened in the test field.

Cultivar positioning in view of AUDPC for every time of the review, none of the cultivars assessed

was totally impervious to leaf scourge pathogen. Information in view of the AUDPC esteems

Bergen, Goliath and Oranza were decently defenseless to A. dauci. Ithaca and Fullback turned out

to be less powerless to this pathogen. Idaho, Canada, Eagle, and Indiana were profoundly

vulnerable and Kamaran, Napa, and Nevis were powerless to leaf scourge pathogens (Gugino et

al., 2007).

Alternaria leaf blight infection of carrot brought about serious loses in development and

creation of carrot harvest in everywhere throughout the world. Because of these misfortunes carrot

cultivators are confronting financial emergencies. So there is a need to control Alternaria leaf

scourge (Geeson et al., 1988).

Nega et al. (2003) recommended that for managing the disease and keeping the disease

under the check, disease free seed should be used, roguing of infected plants should be done,

burning of diseased plants, soils should be well drained and monocropping should be avoided. For

the management of seed-born inoculum, hot water treatment should be very effective in which

seed is treated with hot water at 50oC for 20-30 minutes. This treatment significantly causes fungal

spore germination loss.

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Farrar et al. (2004) recommended that for the proper management of Alternaria blight of

carrot, routine based fungicidal application is very much necessary for reducing the incidence.

Under the high inoculum pressure a single management strategy may not be suitable so multiple

fungicidal application is essential in order to reduce the disease incidence and increase the

economic yield and quality of the produce.

Germination is simply the procedure by which a spore changes itself from a lethargic

condition of low metabolic action to high metabolic exercises, since it is the procedure amid which

metabolic and physiological exercises are reestablished. Think about on various plant concentrates

to check its impact on spore germination of Alternaria dauci uncovered this is the best strategy to

control infection alongside sparing the earth. Onion, Tulsi and Strychnine tree removes at three

distinct focuses were utilized against various contagious spores. Comes about demonstrated that

at convergence of 50, 75 and 100 ppm 40%, 60% and 90% spore germination was recorded (Singh

et al., 2014).

Effective management of Alternaria diseases can be done through combined strategy of disease

free seed, sanitation, crop rotation, resistant cultivar selection and judicious application of

fungicides (Soteros, 1979).

Wells and Merwarth (1973) proved that Alternaria leaf blight can be effectively managed

with the application of chemicals. For the commercial management azoxystrobin, chlorothalonil

and iprodine are used and 80% incidence was reduced after third spray.

Hardison (1976) found that mycelia growth of Alternaria radicina on PDA was entirely

suppressed by the application of propiconazole at 30 ppm followed by Ridomil MZ (mancozeb +

metalaxyl), Daconil (chlorothalonil) and Antracol (propineb) was least effective to reduce the

mycelial growth.

Gillepsie and Sutton (1979) established a disease predictive model for the management of

Alternaria blight of carrot. Through this model timing for the application of fungicides was

predicted. During the four growing season Alternaria blight was effectively managed and

fungicidal application was reduced from 5 to 1 as compared to regular schedules. Alternaria blight

was effectively reduced by triademefon upon infection.

Mirkove (1979) checked that fungicidal seed treatment like Vitavax (carboxin) + Thiram

and Voronit at the rate of 2g per Kg seed is effective against Alternariablight of carrot.

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Bollen et al. (1983) reported that Contaf with active ingredient hexaconazole was very

effective and at 1000 1000 µg/ml concentration ceased the mycelial growth of the fungus.

Jat and Jain (1988) checked seven fungicides i.e. Difolatan 80 WP, Dithane M- 45,

Bavistin 75 WP, Blitox- 50, Topsin M and Sulfex 80 WP against Alternaria alternata in-vivo.

Topsin M (thiophenate methyl) at 0.1% concentration with four sprays at an interval

of 20 days was the most effective than Dithane M-45 at 0.3% and

Blitox- 50 at 0.3%.

Strandberg and White (1989) also reported that seed hot water treatment at 45-55°C for 4-

20 minutes reduced the Alternaria dauci population and seed germination was not affected.

Fallas et al. (1992) reported that the in-vivo management of disease can be effectively done

with the help of Blitox (0.25%) or Dithane M-45 (0.25%). Difenoconazole, an EBI fungicide at

the rate of 125 g/Ha when applied with an interval of 21 days showed excellent control of the

Alternariablight of carrot as compared to Mancozeb.

Poissonnier et al. (1995) recommended sprays of iprodione and hexaconazole for the

control of Alternariablight of carrot in France. Resende et al. (1996) reported that the efficacy of

procymidone at 500 and 750g/ha, triflumizole at the rate of 300 and 450g/Ha, thiophanate methyl

+ chlorothalonil at the rate of 500+1250g/ha, chlorothalonil at the rate of

1500g/ha, iprodione at the rate of 750g/ha, copper oxychloride + chlorothalonil at the rate of 600

+ 500g/ha and chlorothalonil + sulphur at the rate of 1125+1300 g/ha in controlling of Alternaria

dauci on carrot. Iprodione and procymidone gave the best disease control and yield.

Schwarz et al. (1998) tested the efficacy of five fungicides i.e., difenoconazole,

azoxystrobin, iprodione, chlorothalonil and macozeb against Alternaria radicina after the

first incidence in the field. Best control was obtained with 3 sprays at

12- day intervals. It is suggested that chemicals should be applied immediately after onset of

symptoms.

Mazur et al. (2005) concluded that Amistar 250SC (azoxystrobin) showed higher efficacy

in controlling Alternariablight of carrot when the disease had already established under field

conditions.

Kumar et al. (2006) worked on different fungicides belonging to different fungicidal

groups on the incidence of Alternaria brassicae which causes blight disease in radish. The results

61

concluded that chlorothalonil showed effective results and reduced the fungal mycelial growth up

to 0.2 percent.

Singh and Singh (2006) checked the efficacy of various contact and systemic fungicides

under the controlled conditions and found that hexaconazole was very effective at 250ppm reduced

the mycelial growth of Alternaria alternata. While the other fungicides like mancozeb, copper

oxychloride, copper hydroxide, chlorothalonil, azoxystrobin and propineb were effective but their

effectiveness was least as compared to hexaconazole at same concentration so at higher doses the

mycelial growth was greatly reduced to a great extent. Under the controlled conditions, mancozab

was least effective even at 250ppm

Rogers et al. (2010) evaluated three fungicides viz. azoxystrobin, chlorothalonil

and boscalid against Alternaria dauci. It was found that azoxystrobin reduced the conidial

germination ranging from 0.01 to 0.37 µg/mL, Chlorothalonil reduced the conidial germination

ranging from 0.08 to 0.09 µg/mL and bascalid reduced the conidial germination ranging from 0.09

to 0.59 µg/mL. So, from these results, A. dauci was very sensitive to chlorothalonil as compared

to azoxystrobin and bascalid.

Ben-noon et al. (2001) conducted an experiment under which the viability of nine

fungicides was resolved in two field tests. All fungicides decreased ailment seriousness, yet there

was noteworthy distinction in viability among them. The best were difenconazole and

chlorothalonil, less compelling were copper hydroxide, tebuconazole, trifloxystrobin and

mancozeb, the slightest viable were flutrifol, propineb and iprodione forthe management of

Alternaria blight under field conditions.

Ben-Noon et al. (2001) also suggested that alternating chemicals would be more suitable

than using single chemical. Recently available fungicides like azoxystrobin and difenconazole

provided better control of this disease as compared to traditional fungicides like copper

oxychloride and sulphur.

Sidlauskiene (2001) has demonstrated the efficacy of Amistar 250 SC, a strobilurin

fungicide in reducing disease prevalence (90.8%) and intensity (88.8%) of Alternaria blight of

tomato.

Prasad and Naik (2002) reported Indofil M- 45 to be most effective against

Alternariasolani causing Alternariablight on tomato.

62

Mohit et al. (1997), Dhanbir et al. (2002) recommended that in early blight of potato caused

by Alternaria solani the effectiveness of Dithane M-45 in controlling the disease has been well

demonstrated under field conditions.

Farrar et al. (2004), Saude and Hausbeck (2006) recommended that foliar application of

fungicides like difenoconazole, chlorothalonil, iprodione, azoxystrobin have been reported to be

effective against A. radicina.

Jensen et al. (2004) has investigated the role of bio agents in managing Alternaria blight

of carrot. Highly infected carrot seed with A. dauci / A. radicina when bioprimed with

Clonostachys rosea strain IK 726, reduced the incidence of the pathogen to 4.8 per cent with a

lower infection rate.

Singh and Singh (2006) reported that carbendazim and mancozeb to be most effective

against Alternaria species. Mixture of Carbendazim + mancozeb was also found to be equally

effective against the Alternaria solani.

Alkseeva (2009) conducted field trials in Russia and concluded that Score

(difenconazole) was quite effective for management of Alternaria blight of carrot on

appearance of first disease symptoms. Persistent trimming in same field brought about the lack of

basic supplements and weakness of product to disorder when contrasted with that in which harvests

were turned. Therefore there was nonstop decrease in natural product yield and plant development

(Zhou and Zhao, 2011). Utilization of fundamental supplements incited the resistance in plant,

lessened the seriousness of ALB sickness of carrot and expanded agricultural parameters of plant

(Abada et al., 2009). Utilization of borax (20 Kg/Ha) with zinc sulfate (14 Kg/Ha) created fiery

plants and high return when contrasted with untreated plants (Attanayake et al., 2015).

Conclusion

Proper forecasting of disease along with the use of resistant varieties and post-infection treatment

of chemicals and plant extracts is favorable for the proper management of Alternaria blight of

carrot.

63

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