Tea Pest Management

SHAHJALAL UNIVERSITY OF SCIENCE & TECHNOLOGY

An AssignmentOn

“A scenario of tea pest in tea garden of Bangladesh”

Course Title: Entomology & Tea Pest Management SessionalCourse no : FTT 319Submission Date: January 3rd, 2010

Submitted to Submitted by

Dr. Iftekhar AhmadAssestant ProfessorDept. of Food & Tea TechnologySUST

Md. Saidur Rahman KhanReg. No. 2006337004 Semester 3/1Dept. of Food & Tea TechnologySUST

Tea production in Bangladesh is greatly hindered due to a number of pests and diseases. Various insects, mites, nematodes, algae, fungi, and weeds are major yield depressants. So far 29 arthropod pests including 25 insects, 4 mites, and 12 nematodes; and 1 algal and 18 fungal diseases, and 37 predominant weed species have been recorded. However, these pests become epidemic in certain year, season or in some gardens. The pest status as major or minor often depends upon the prevailing climatic and ecological conditions. More than one pest or disease may invade conjointly or simultaneously to the same bush or same garden in a particular season or time. Tea pest and tea productivity are two antagonistic factors. Literally the word pest (La. Pestis, pestillance) is a collective term for a wide range of organism like virus, bacteria, algae, fungi, insects, mites, birds, rodents, etc. which are noxious, troublesome and destructive to crops, food supply and human property. In Bangladesh tea, the annual crop loss due to various pests is estimated to be about 10-15 percent.

What is Tea?

Tea is a cross-pollinated plant. Tea plant is a small tree or shrub which may grow to a height of about 9m. in nature. The botanical name is Camellia sinensis. Leaves are alternate, elliptical, lanceolate or ovate, leathery and smooth, 1.5-2.1 cm. in length. Young leaves are more or less pubescent with point buds. Flower buds originate singly or in cluster from leaf axils. Flower white and fragrant with 5-7 leathery permanent sepals forming a ring, 5-7 white obviate, emarginated, internally concave Patel. Stamen is numerous, long, with yellow 2-celled anther.

Pest

The pest is always a living organism. Whether an organism is a pest or not, basically depends on a value of judgment. It may not be a pest in its natural habitat, but its status can be changed when it comes into conflict with man. A pest has been defined in number of ways like-

Any organism that causes trouble, annoyance or discomfort is known as pest.

Living organism which causes harm to our health, properties or well being are known as pest.

Organism which attack, feed upon and injure plants parts or belonging and causes economic losses are known as pest.

eg.Termite, Ants, Mite, Looper caterpillar,etc.

Tea Pest

The pests that create a handicap in the tea population are called the Tea pest.

e.g. Termite, Ants, Mite, Looper caterpillar etc.

Fig: Beetles Fig: Tea Mosquito Bug Fig: Looper Caterpillars

Fig: Flies Fig: Mite Fig: Termite

Types of Tea pest

Based on ecological view pest can be divided into two groups:-

(a) `r` pest(b) `k` pest.

`r` pest:- These pests are highly reproductive potential that are able to induce sudden and wide speed attack under favorable conditions.

`k` pest:- These are slowly reproductive potential. They are more stable i.e. they live in stable habitat and are less migratory in habit and posses prolonged generation time.

According to the view of status pest can be categorized into two types:-

(a) Key pest.

(b) Occasional pest.

Key pest:- These type of pest have highly reproductive potential and prolonged stability in the habitat. A singal crop may have one or more key pest which may or may not vary between different seasons and regions. Key pests owe their status to several factors such as their high reproductive potential and types of induce injury to the host plant. They cause major damage in every season and sometimes unless control.

Occasional Pest:- The pest that cause damage of plants and animals in the interval seasons is termed as occasional pest. They do not inhabit but periodically invade crops for a short period causing colossal damage.These pests are mobile and migratory in habit.They exploit maximum food intake in short time.Their population growth is characterised as `boom and bust` and dominated large scale migration.

eg. Locust, Armyworms, Aphid, etc.

Based on importance pest can be divided into four types:-

(a) Vectors.(b) Benefactors.(c) Major pest.(d) Minor pest.

Vectors:The pest that transmit diseases are called vectors. They induce injury to plant and animals by feeding or sucking the host tissues.

Eg. Insects, Clostridium, etc.

Benefactors :The pests which are directly or indirectly involve in human welfare are called Benefactors.

eg. Predators/Parasites and many productive insects like Honeybee,Silkworm and Lack insects,etc.They are useful and denoted as productive insects.

Major pest: They are potential, remain fairly persistent throughout the season in a cropping system or in a restricted area and inflict a sustantial damage to the crop plants. They live in stable habitats and less migratory in habit and posses prolonged generation time. They are termed as major pest because of their basic biology, frequent occurrence and wide range of host plants.

eg. Ants, Codling moth, Tsetes files and some beetles.

Minor pests: They occasionally induce to crop plants but do not cause economic damage. Often their effect on the plants is invisible. They may be limited to particular crop plants or may prefer other plants as hosts.

Secondary/Sporadic pest: Sometimes in a particular cropping system a small proportion of such minor pest become abundant and inflict economic damage, these are then called economic Secondary or Sporadic pest. The number of these pest are usually controlled by biotic and abiotic factors which occasionally breakdown , allowing the pest to exceed its economic injury threshold.

Sucking pest Chewing pest

Major Tea Pest

Caterpillar

Bunch

Looper

Red slug

Flush worm

Beetle

Cockchafer Beetle

Matalic green

Borer

Termites

Live wood

Scavenging

Insect Pest

Tea Mosquito Bug

Thrips

jassid

Mites

Red scarlet mite

Pink mite

Fig: Diagrammatic representation of of a tea bush and location of pests on it

Locational characteristics of Bangladesh tea pest

Many pests are cosmopolitan and distributed over a wide range of ecological zones. It is observed in the world tea that Helopeltis, Red spider mite and Scarlet mite are distributed between 00 to 270 N latitude. Some pests such as Flush worm, Aphid and Jassid are distributed in the area between 240 S-110N. High soil PH and clay loams are suitable for some pests like termites and nematodes. Aspect/topography influences the climates and moisture which sometimes strictly controls helopeltis survival in Sylhet Zone but restricts in Chittagoan Zone. Even soil type and geographically isolated area does not face this acute Helopeltis problem. At very low temperature in cold weather period only termite is activate while during high temperature and high humidity most of the foliar pests of upper and mid canopy such as Thrips jassid , Tea seed bug, Red scarlet mite, Pink mite, Purple mite, Caterpillar Looper, Red slug, Flush worm.

Pest succession in Bangladesh

Helopeltis, Red spider mite

Flushworm

Aphid, Jassid, Thrips

Leaf roller, scale insect

Scarlet, pink and purple mite

Bag worm, Faggot

Termite

Cricket

Termite

Nematode

The overall pest-spectrum of Bangladesh tea is similar to that of the Brahmaputra valley , Assam. It seems that most of the major pest and diseases of tea have been introduced initially from the contiguous areas of Cachar,Assam or from the legacy of forest trees and wild or cultivated plants in this area. During the last 132 years of Bangladesh only a few of the recorded 53 pests and diseases have become major in status. Most of these pest are still minor and causes occasionally damage.

The status of a pest in an outcome of the balance between pest regularoty forces in nature and the intrinsic biological adaptability of the pests. The trend of pest succession and the attainment of epidemic status reveal a change of pest-status during the last two and a half decades. Red spider mite, tea mosquito bug and termite predominate and are widely distributed in all tea valley circles. Other pests like tea flush worm, jassid, aphid, scarlet mite, blister blight disease are found to be restricted in localized areas or ecological zones.

During 1965-80, an exploratory survey of pests in different valley circles of Sylhet tea was conducted. It reveals that about that about 60 % out of 163 tea estates of Sylhet are invaded by pests. About 35% of tea estates in Monu-Doly circles and 82 % of tea tea estates of Luskerpur circles are invaded, while other circles remain below the average of whole Sylhet zone given below:

Pests Sporadic Epidemic Status

Red spider mite 1950 1959-74 Major

Tea mosquito bug 1968-70 1975-78 Major

Green caterpillar 1960 1962 Major

Tea seed bug 1960 1962 Major

Flusworm 1960 1963-66 Major

Blister blight 1960 1964, 75 Major

Scarlet mite 1963 1966 Major

Purple & pink mite 1966 1969 Major

Green fly 1970 1985-86 Major

Common tea pests in Bangladesh

In Bangladesh tea, so far 25 insects, 4 mites and 10 species of nematodes have been recorded. Only few of them have become major pests while most of them are minor and localized and cause occasional damage. In tea, a major pest of today may be minor of tomorrow. On the contrary, more than one pest may invade conjointly. Pest of tea and their nature of injury are presented in table.

Fig: Map of Bangladesh showing the existing and proposed Tea growing areas.

Insect order related to tea:

It is establish today that the insect are the dominant group of living organism on the earth. So far 29 orders are clearly identified. Among the 29 order of insects, the following orders are directly or indirectly harmful to tea plants-

Lepidoptera Coleoptera

Orthoptera Isoptera

Hemiptera Neuroptera

Thyasnoptera Hymenoptera

Diptera

Tea pest in the different parts of a Tea plant:

Lists of Tea pest which attack at different parts of a tea plant are given below:-

Different parts of a Tea plant No of pest % of pest

Foliage 134 58.9

Stem 300 24.1

Root 160 12.8

Flush/Flower 30 2.4

Fruits 9 0.7

Seedlings/Nursery 14 1.1

Crop loss assessment in the tea world:Importance of pest control is highlighted through cross loss estimation. Severe infestation by many foliar and soil pest leads not only to crop loss but to capital loss resulting from the death of the bushes. There have been several assessments of crop loss in the world tea due to pests presented by different authors:

Table: Crop loss in world tea

Tea growing area and reference report of crop loss

Tea in Asia( Cramer, 1967) 8%

Loss to be anywhere in India(Banerjee, 1976) 6-14%

Overall india(Das, 1960;Jain, 1977) 15%

Overall N-E, India(Banerjee, 1993) 15%

Bangladesh(Sana, 1989) 15%

Common tea pests in Bangladesh:

In Bangladesh tea, so far 25 insects, 4 mites and 10 species of nematodes have been recorded. Only few they have become major pests while most they are minor and localised and occasional

damage. In tea, major pests of today may be minor of tomorrow. On the contrary, more than one pest may invade conjointly. Pest of tea and their injury are presented in Table below:

Order Species(Common Name)

Pest stage

Pants parts attacked

Nature of damage

Status

Hemiptera Helopeltis theivora waterhouse(Tea mosquito bug)

Nymph, adult

Young leaves, shootes

Sucking Major

Hemiptera Empoasca flavescense Fab(Green fly/jassid)

Nymph, adult


Sucking Major

Hemiptera Taxoptera aurantii Bayer( Plant lice/ Aphis)

Nymph, adult


Sucking Major

Hemiptera Poecilocoris latus Dall(Tea seed bug)

Nymph, adult

Flower, seed, buds

Sucking Minor

Lepidoptera Clania cramerii (Bag worm)

Larva Leaves, shootes, buds

cutting Minor

Lepidoptera Clania sikkima (Faggot worm)

Larva Leaves, shootes,buds

Cutting Minor

Lepidoptera Clania destructor Larva Leaves, shootes, buds

Cutting Minor

Lepidoptera Biston suppressaria Green (Looper caterpillar)

Larva Young and mature leaves

Cutting Minor

Acarina Oligonychus coffeae Nietner (Red spider mite)

Nymph, adult

upper surface of the mature leaves

Sucking Major

Acarina Brevipalpus phoenicis (scarlet mite)

Nymph, adult

upper surface of the mature leaves

sucking Minor

Tylenchida Pratylenchus loosi (Meadow/root lesion nematode)

Adult Root sucking Major

Tylenchida Aphelenchus sp.(Saprophagous nematodes)

Adult Root Sucking Minor

Tylenchida Helicotylenchus spp. (spiral nematodes)

Adult Root Sucking Minor

Tylenchida Meloidogyne spp. (Root-knot nematodes)

Adult Root Sucking Major

Description of some major pest in Bangladesh:

Tea Thrips:General description:

Scientific name: Scirtoturips dorsails Hood.Order: ThripidaeStatus: Major pest in nursery, young tea and tea recovering after pruning. Distribution: Zimbababue, Africa Bangladesh.

Nature of damage: Thrips prefer unopened or partly opened young leaves and buds. Both adults and nymphs generally feed on them and cause laceration of the tissue, which appear as large number of streaks. The leaves surface become uneven and malty as feeding marks on leaves. As a result the growth of the affected leaves becomes stunted and immature tea leaves may look burnt.

Life cycle: The adult is dark brown and the egg is laid singly in the tissues of leaf buds and young leaves. The egg is bean shaped, slightly narrower at one end and colorless. The incubation period varies from 6-7 days and newly heated nymph is at first white and latter turn to yellow orange in color. The life cycle consist of egg, nymph, prepupa, pupa and adults. After the second moult a prepupa is formed. Total duration for nymphal and pupal stage varies from 6-10 days during summer.

Fig: Life cycle of Tea ThripsControl measure:

(1) Physical control: (a) Mechanical control:

Shorten the plucking round during infestation.

Hard plucking may be practiced during severe causes.(b) Cultural control:

Establishment of optimum shade in plantation and overhead shade in nursery.

Keeping the selection weed free. Improve drainage condition.

(2) Chemical control:

Thrips prune area should be regularly sprayed with Agrothion 50% EC at the rate of 1.25 liters per hectare diluted with enough water to over the affected areas or with Thiodin 35% EC at rate of 1.25 liters per hectare.

(3) Biological control:

The natural enemies such as lady bird beetles, syrphid larv, lace winged flies and several types of insects can destroy this pest.

Jassid:

General description:

Tea jassid Empsaca flavescens(Fab)are commonly known as green fly. It is a major pest of nursery and young tea. It is more pronunced in unshaded areas then shaded areas.

Nature of damage:

The damage is caused by both adult and nymphs,which suck the sap of young leafs and occasionally tender stem. Nymphs are responsible for greater damage than the adults.The growth of the affected leaf becomes uneven and the leaves usually curl downwards seeming to be boat shaped.the leaf margins become recurved and turned brown and dry up (rim blight).This insect is highly polyphagous.

Identifying characters:

Adult jassids are small yellowish green and 0.5 cm long forewing being pale yellow in colour.Male is smaller in color.Nymphs are without wing and it can jump quickly when disturbed.

Life history:

Adult female lays eggs singly inside the soft tissue of petioles, mid rib and veins of young leaves .The incubation period varies from 6 to 13 days . Nymphal period varies from 10 to 15 days. there are four moults of nymphs before it becomes adult.

Fig: Life cycle of Jassid

Control measure:

1.physical control:

(a) Mechanical control:

Shortening of plucking round during infestation. Hard plucking may be practiced during severe cases. Target point especially the top shoot and the under surface of young leaf.

(b) cultural control:

Establishment of optimum shade in plantation and providing overhead shade in nurseries.

Cleaning the section and keeping the section weed free. Improvement of drainage condition.

2. Chemical control:

C.QS.S Ekatin 25 E.C in 1.12 litre in 560 litres water/ha

S. Rogor 40 E.C in 1.12 litre in 560 litres water/ha

3. Biological control:


Aphid:


Tea aphid Toxoptera aurantii bayer are commonly known as plant lice. It is major pest of tea nursery and young plantation. It is widely distributed in Bangladesh, India and srilanka .It generally attack on the plant in December.

Nature of damage:

Nymphs suck the sap. It attacks the tender stem, undersurface of young leaves and buds. Affected leaves loose their sap and become crinkled and curled and the growth of shoot is retarded. It is highly reproductive pest and multiplies rapidly resulting in a heavy build up of colonies within a short time. Aphids secretes sweet honey from its chronicles on the leaf surface.

Life history:

Both the nymph and adult suck the plant juice. They are small dark brown. The nymph are wingless females, dark brown and 1-2mm long. A reproductive female may give birth to as many as 100 young during a life time of 2 to 4 week. Sometimes reproduction takes place parthenogenetically i.e without fertilization by male , female give birth to youngs.

Fig: Life cycle of Aphid

Control measure:

1. Physical control:(a) Mechanical control:

Hand pick and kill them. Cut the infected part. Maintaining the plucking system.

(b) cultural control:



2. Chemical control:

C.QS.S Ekatin 25 E.C in 1.12 litre in 560 litres water/ha

S. Rogor 40 E.C in 1.12 litre in 560 litres water/ha

C.S Roxion 40 E.C in 1.12 litre in 560 litres water /ha

3. Biological control:


Looper caterpillar:


It is a minor pest.It`s scientific name is Biston suppressaria (Guen).It is one of the most destructive pest of tea.The incidence of this pest has been recorded in the district of Doorars and Cachar since 1900.In Bangladesh tea ,a several outbreak occurred in several tea states of Sylhet in 1963 and present sporadic and localized incidence is observed in lower valley circles of Bangladesh Tea.

Nature of damage :The young caterpillar make hole at the margin of leaf, bite of small pies along the margin and eventually the whole leaf is completely eaten away.In a several attack, the bushes are completely stripped of leaf.

Life history:The moth is grey, finely speckled with black.The fore wing has a yellow antimedial bend and both wings bear an indistinct sinuous yellow median line and a post median maculated band with

a marginal series of yellow spots. The wing span of male is 40-50 mm. and of female is 60-70 mm.Eggs are laid in heaps,each containing 200-600 eggs covered with buff colour hairs , on the trunk of shade trees or any other site of tea.The eggs are cylindrical bluish green and turn dark –brown befoe hatching.Incubation period varies 8-10 days .Newly hatched larvae are dark brown in colour.The cater pillar has a pro leg at the 6 th segment of the abdomen.The larval period is about three weeks.Before population they move to the ground and pupated in the soil under the tea bushes. .

Fig: Looper caterpiller

Control masure:1. Physical control:

(a) Mechanical control: Hand pick and kill them. May be killed by means of bamboo pole to which a bundle of thatch grass is

used like a broom.(b) Cultural control:



2. Chemical control: Dimecron 100 E.C @ 0.35 lit/ ha or Bidrin 87 E.C @ 0.56 lit/ ha.

3.Biological control:


CRICKET:


Scientific name:

Brown cricket : Brachytrypes pertentosus

Mole cricket : Gryllotalpa Africana

Type : Minor, Nochternal Distribution : North-East India, Sri Lanka, Africa , Bangladesh Region of attack : leaves & tender shoots , also stem & roots of young seedlings Time of infestation : around the year, but mostly in October-February

Nature of damage:

Come out at night & cut off leaves & tender shoots Also cut through the stem & roots of young seedlings Cut young plant 2-6 cm above the ground

Life history:

Adult brown cricket is blackish brown insect Length is 1.5-2cm with long antennae Nocturnal &live in burrows Eggs are laid on the soil surface , at the bottom of the burrow Hatching time is 4 weeks Young nymphs live for 15 days in maternal burrow Development of adult from nymph take several months& adult is seen in June –July

Control measure:

1. Physical control measure a) Mechanical control :

Hand picking & killing Destruction of specially female insect to reduce the reproduction rate

Removal of infested plant part Burrows should be find out & plucked off Pour 1/2 spoonful of waste engine oil / PDB crystal per hole until cricket appear

& then destroy by hand. Then burrows have to pluck off .b) Cultural control:

Ensure proper drainage facilities Regular weeding should done Cleanliness is a major remedy

2. Chemical control: In severe infestation , ‘Bran baits’ containing Heptachlor / Dieldrin should be

spread @ 10-20 lbs/acre in 2-3 consecutive night Strip spray with Dieldrin 2% dust or Dieldrin 20EC @ 0.5 lbs/acre The natural enemies such as lady bird beetles, syrphid larv, lace winged flies

and several types of insects can destroy this pest. 3. Biological control:


FLUSH WORM:

General descripion: Scientific name : Laspeyresia leuconostoma Type : major Distribution: North & South India, Bangladesh Region of attack : mainly tea flush Time of infestation : in Bangladesh , generally March to May

Nature of damage: Larvae attack top 2 leaves & a bud of tea Larvae roll up the top leaves & tie them together. It remain inside of the fold of

bud or young leaf & feeds by scraping off the tissues of upper surface The affected flush becomes distorted , crinkled , rough & brittle with brownish

coloration & internodes become shortened Immediately after pruning , newly emerged flushes are severely infested with

flush worm

Life history:

The insect is very tiny moth , about 10-13cm long Head & thorax are brownish Abdomen is grayish brown Wings color is mixture of dark brown , grey & violet with yellow-white streak Egg is minute , oval , & yellowish Eggs are laid singly on the under surface of 2nd /3rd leaf Newly hatched larvae tie up top leaves with saliva Full grown larvae is 9-10mm & greenish or brownish in color Larval period is 3-4 weeks Pupa is 5-6mm long , greenish-yellow at first & then turned into brown They live inside the roll , occasionally outside into leaf petioles Pupal period is 10-15 days long

Control measure:

1. Physical control measure:

a) Mechanical control : Hand picking & killing Destruction of specially female insect to reduce the reproduction rate Removal of infested plant part Thinning the attacked leaves Pluck the janam leaf

b) Cultural control: Ensure proper drainage facilities Regular weeding should done Cleanliness is a major remedy Maintaining weekly pruning cycle

1. Chemical control measure: Dipterex 50EC @ 2.24 ltr/ha Diazinon 60EC @ 0.63 ltr/ha Dimecron 100EC @ 0.35ltr/ha

These should apply after plucking

Tea mosquito bug (Helopeltis theivora):


Tea mosquito bug, Helopeltis theivora is the most serious pest of tea in Bangladesh. There are several species of Helopeltis attacking tea, cocoa and cinchona in Sri-Lanka, India, Indonesia and Africa. In Bangladesh, the trend of successive invasion by this pest indicates that sporadic

incidence was observed during 1968-70 but it attained outbreak status during1975-78. About 15-34 percent of tea estates in Sylhet is still found affected but with a declining trend.

Nature of injury:

A few to innumerable feeding punctures or spots are found on young tea flush. Spots are light-brown, sunken, translucent, 1-5 mm in diameter, with dark margin and sometimes a drop of brownish liquid oozing out of the centre of the wound. Within a few hours, the spots turn black and dry up, later the necrotic leaves curl and become crinkled. Young stems or petioles and buds become brown.

Fig: Life cycle of Tea mosquito bug

Control measures:

1. Physical control:

(a) Cultural control:

Establishment of optimum shade in plantation Cleaning the section and keeping the section weed free. Improvement of drainage system.

(b)Mechanical control:

Three-year pruning cycle in preference to four-year pruning cycle should be adopted.

1. Chemical control: Of the approved pesticides, Thiodan is found to be superior to others in

reducing the pest population, while Agrothion, Malathion and Sumicidin

are more or less equitoxic and remain effective upto 15 days after spraying.

2. Biological control: The population of the pest is kept below the level of economic damage by

various parasites such as Asympieslla India, Bethylus distigma, Angitia sp

Nematode Pests:

Nematodes are widely distributed through the world and are known to live in widely different habitats. They may be saprophagous spp. Feeding on decaying organic matter or predaceous spp. Which feed on algae, fungi and other plants. They are commonly called roundworms, eelworms or nemas. Plant parasites nematodes are important pest on many cultivated plants including tea, coffee etc. They may attack any part of the plant but most species limit their attack to roots or underground parts.

Life cycle:

Life cycle is simple and 20-60 days duration. Eggs hatch into larvae and transfer into adults. There is no definite metamorphosis but moults occur. Eggs may remain

Fig: Life cycle of nematode

dormant in the soil for long period; some chemical substances from the plant being seemingly needed for hatching. Some nematodes are endoparasitic i.e pass their entire life inside plant roots, while others are ecto-parasitic or non-sedentary ones which pass a part of their life inside plant roots and hence via the soil to others plant roots.

Key to plant parasitic nematode:

3. Sedentary root nematode a. Cyst-forming nematode………………. Heterodera sp.b. Root-knot nematodes………………….. Melodogyne sp.

Tea Nematod in Bangladesh:

Nematods are importants pest of tea in the nursery and new clearing and invade tea seedlings upto 8-9 moths old, in young plantation.Tea in India, Srilanka and Africa are reported to be attacked by root knote nematode, Meloidogyne sp , Root lesion nematode.(Paratylenchus loosi, P. brachyrus), False nematode,Xiphenema spp.Sheath nematode,Hemacycliophora longicoudata.dagger nematode,Xiphinema radicicola,spiral nematode,Hericorylenchus spp. In bangladeshtea,Root lession nematode,paratylenchus loosi,spiral nematode (Hericorylenchus spp).Tylenchus spp. And aphelenchus spp. Are mostly associated.Root-knot nematode,meloidogne spp. is occasionally reported.

A. Root lesion nematode,Paratylenchus loosi loof:These are migratory and endoparasitic nematodes on the roots of young tea plant.they are short,cel shaped,0.45-0.75mm. in length,the head is strong witg stout stylet.they usually feed on feeder roots and gain entrance into plant tissues causing lesions on the epidermal cells.as a con sequence of feeding ,the tissues of the cortical zone die and leads to the formation of dark necrotic areas or lesions which are exposed when the bark is peeled.These lesions then gradually expand and girdle the root,thus cutting off food-food supply to the tip end and leading to the ultimate death of the storage root. These nematodes may undergo a stage of anabiosis whereby their feeding actively is markedly reduced.They may viable in this state for as long as 3-4 years these nematodes are abundant and may pass from old roots to the new young tea.

B. Root –knot nematode, Melodogyne spp. : Both root –lesion and root knot nematodes are reported from java,West Africa, Belgium Congo, Trinidad, and as a pest of the cacoa plant. The root knot nematode is a serious pest of tea in Sri Lanka. Young seedling as well as clonal plants in the tea nursary are attacked.Root-knot nematodes infestation is easily recognizable from its charecteristics tumor-like galls on the infested plant roots. The female root knot nematode larvae mature within the root tissue, transform from typical eel-form to a sausage-shaped form and remain sedentary.

Tea pest management

Tea pest management is a vast topic involving intricate and interwoven matters of relevant disciplines of bio as well as physical science, health, environment, social and economic aspects are also dealt with. Tea pest and tea productivity are two antagonistic factors. Literally the word pest (La. Pestis, pestillance) is a collective term for a wide range of organism like virus, bacteria, algae, fungi, insects, mites, birds, rodents, etc. which are noxious, troublesome and destructive to crops, food supply and human property. In Bangladesh tea, the annual crop loss due to various pests is estimated to be about 10-15 percent.

Some scale for Pest measurement:

There is some scale for the measurement pest injury, such as-

(a) Economic danger.(b) Economic injury level.(c) Economic threshold.(d) Equilibrium position.

Economic danger:

The economic danger is defined as the amount of danger or injury done to a crop which will financially justify the cost of taking artificial pest control measures. As a general guide for most agricultural crop pest, it is agreed that an insect species can attain pest status when there is 5-10% crop yield losses. Obviously a loss of 10% plant stand in a cereal or sugarcane plantation is not serious, whereas the loss of a single nature tree plant like Mango, Citrus or Mahogany tree is much great for economic consideration.

Economic Injury Level:

It can be defined as the lowest number of insects that will cause economic danger or the minimum number of insects that would reduce yield to the gain threshold. However Economic Injury Level varies depends on crop to crop, seasons to seasons and area to area and human scale of values.

Economic Threshold (ET): It indicates the number of insects at which the pest management action should be taken in order to prevent an increasing pest population from reaching the Economic Injury Level.

Equilibrium position: Equilibrium is the average population density of a pest over a long period of time. The pest population will fluctuate above this equilibrium according to the influence of density depended factors.

Integrated Pest Management:

In 1967 the integrated pest control strategy is defined as Pest Management by the experts of FAO panel.The concept of pest management is now internationally accepted as Integrated Pest Management (IPM).Pest management implies the regulation of pest activity by adopting of suitable methods so as to minimize their injurious effect and to maximize the activities of biocontrol agents without jeopardizing the natural balance.

IPM is a multidimentional cohesive system of selection,integration and implementation of pest control strategies based on the predicted ecological and socio-economic consequence. The underlaying concepts and methods of IPM aim at developing and economically viable and environmentally accepted system of crop protection.

IPM is virtually concept a of pest population management system which utilizes almost all types of proven pest control tactics to reduce and maintain the pest population density below the level of economic threshold of crop damage while maintaining the environmental equality.

Integrated Pest Management (IPM) component:

-The agroecosystem.

-The plants.

-The pest.

-Preventive control-resistant varieties, cultural management, plant spacing and sanitation, etc.

-Suppressive control –Parasitoids and predators, microbial agent, pesticides, etc.

Steps or methods of IPM:-

(1) Identification of target diseases and pest.(2) Identification of management unit.

(a) Agroecosystem.(b) Operational area.

(3) Developmental strategies:-(a)Study of ecology and epidemiology of pest to establish the biotic inter links.(b)To reach a dynamic equilibrium at a higher plant.

(4) Establishment of economic threshold.(5) Development of pest monitoring technique.(6) Descriptive, predictive system i.e. analytical modeling.(7) Optimization of management decision:

(a) Pest attack.(b) Economy of farming system and(c) Crop protection technology.

Pest Forcasting and Pest Monitoring:The object of forcasting is to provide information in advene of pest attack on what the pest simasion is likely to be. The main purpose of forcasting is the region. Incontrast,pest scouting,or monitoring, is concerned with obtaining real time information on the current level and obten in association with a pre-determined action threshold population level.If pest scouting provides information at the time decitions are made,it may further reduce uncertainly and improve pest control be known and the natural controls maximized.The methodology of pest monitoring scheme depends upon the crop or other resources,the type of pests involved, environmental conditions, and the economic resources. In tea culture, several pest scouting techniques have been designed by using Pest Survey Card and Pest Status Reticule-1,11,and nematode and Weed Density Sampling Techniques.

Conclusion:

Tea a popular beverage made from the leaves of evergreen shrub or tree Camellia sinensis, family Theaceae. It is predominantly an agro-based export-oriented evergreen crop in Bangladesh and a perennial crop grown as a monoculture on large contiguous areas. Under natural conditions, a tea plant grows to a small tree but it is configured into a bush by sequential pruning and other silvicultural practices, viz tipping, plucking and by harvesting the optimum vegetative produce. Generally the insect which attack the tea crops are known as tea pest. About 15% tea production could be lost per year by various tea pest particularly insects, mites and nematodes. Scientists and researchers contributed to estimate the tea pests worldwide and according to them 1034 species of arthropods and 82 species of nematodes infest tea plants. These pests are enable them to attack in all parts of a tea plants .Among different parts of a tea plant, foliage pests are in the highest number. Mainly the importance of tea pest is found in the destruction of tea crop and in the rare case in the beneficial effect.

Reference:

1. Abbasi F.H. and K.A. Akbar. 1962. Studies on the control of eelworm in The tea nurseries.2. Sana, D.L. 1974 – 1989. Researches on Pest Management. Pest Management div. Annual reports. BTRI. Srimangal3. Hajra. Ghosh. N. Tea cultivation: Comprehensive Treatise4. Banerjee, B. 1976b. Pestiside and Pesticides Residues in Tea5. Das, G.M. and Das S.C. 1959. Problems of pest control in Tea. Science and Culture, 24: 493 -4986. Ahmed, Mainuddin. Dr. Tea Pest Management7. Sana, D.L. Tea Science (90 – 155)8. “Tea” Encyclopedia Britannica. 1971

Note: the following of the information of this assignment are collected from many of these references area through online services from Internet.

Tea Pest Management

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