Control measures

Nursery

Heat treatment: Spread soil sand mixture (5 cm thick) on a G.I. sheet. Heat it from below. Sprinkle water periodically. Mix the soil thoroughly by turning. Optimum temperature is 60-65ºC. Soil should not be too hot to hold in the hand. Over heating of soil will lead to manganese toxicity.

Mature tea

Neem cake 2 kg per bush is recommended.

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Insects

The creamy white grub eats away the roots. The main symptoms are ring barking of stem, chlorosis and defoliation. The pest is a serious problem in areas where un-decomposed farmyard manure is used.

Control

Nursery: Heat treatment of soil and use of granular insecticides are practised.

New clearing: Drench Chlorpyriphos or quinalphos 0.05%

1. At the time of planting: 500 ml per pit.
2. Post-planting treatment: Loosen the soil around the bush and pour one litre per bush.

Root mealy bug (Dysmicoccus sp.)

The pest is a problem in the nursery. It sucks sap from the callusing region, mother leaf petiole and axillary buds. This arrests root development; leads to mother-leaf fall and finally death of plant.

Stem borers

Red coffee borer (Zeuzera coffeae)

Mostly seen in new clearings as batches. Young stems are bored and larvae tunnel downward, make holes at intervals to eject excreta and wood particles. Frass and excreta are seen around plants. Alternate host of the pest is coffee and cocoa.

Large hepialid borer (Sahyadrassus malabaricus)

This is a polyphagous pest attacking teak, eucalyptus and lantana. Thick branches (3 cm diameter) are preferred by the pest. Callus tissue and wood form food for larvae. Entrance holes are covered with frassy mat formed with chewed wood and silk.

Control

Cut the affected stem and pour quinalphos using ink filler. Then the holes are plugged with clay paste.

Mites

Several species of mites attack tea plants. They are dry weather pests mostly attacking mature foliage except pink and yellow mites.

Pink mite (Acaphylla theae)

• Important mite pest of tea in southern India, causes considerable damage

• During early stages of attack leaves turn pale and curl upwards

• Severe infestation leads to brownish discolouration

• Attack tender flush, assam jat and assam hybrids more susceptible

The scarlet mite(Brevipalpus australis)

• Feeding leads to brown discolouration of leaves

• Symptoms of attack first appear on either side of the midrib and gradually spread to the entire leaf

• Severe infestation leads to defoliation

• Adult mite is scarlet red in colour and obovate in shape

• Reproduction is by parthenogenesis

• Eggs are bright red, elliptical, laid in clusters

• Incubation period is 7-10 days

• Developmental stages include three legged larva, protonymph and deutonymph

• Each developmental stage is followed by a quiescent stage

• Life cycle completed in 30-36 days

The Red spider mite (Oligonychus coffeae)

• Important mite pest causes considerable damage (more than 18% loss when severe infestation)during the last few years.

• Incidence high during January-May and low during June-December, reaches peak in March / April

• Infestation starts along midrib and veins

• Spreads to the entire upper surface of leaves matured

• Due to feeding, the maintenance foliage turns ruddy bronze

• Infested fields distinct even from a distance

• Severe infestation leads to defoliation

• Mites spin a web of silken threads on the leaf

Control

If infestation is more, quinalphos will be effective. The biocontrol fungi Paecilomyces fumosoroseus is available as wettable powder formulation " Mycomite" for control of red spider mite.

Tea Thrips: Scirtothrips bispinosus

• Prefers young leaves and buds

• Continuous feeding causes lacerations which appear as streaks

• Leaf surface becomes uneven and curled

• Feeding marks on the buds later appear as two parallel lines
• Leaf margins turn yellow

• Attack more pronounced in the fields recovering from pruning

• Leads to inordinate delay in tipping and consequent crop loss

• Adults characterised by their brown abdomen, incubation period is 6-8 days

• Egg hatches into larva, two larval instars, creamy white in color, prominent eyes

• Prepupa and pupae are found in the leaf litter and soil

• Adults emerge from the pupae after 3-5 days

• Weak fliers, dispersal and migration is helped by wind

• Build up starts by Nov/Dec, reaches peak in Feb/March or April/May

Control measures

• Cultural control

  Monitoring the population in the field with yellow sticky traps

  Maintenance of regular shade

• Biological control

  Spray the spore suspension of the entomopathogen, Verticillium lecanii @ 1.5 kg/ha in the evening hours when humidity is more

  Allow predators (Anthocorids and predatory thrips )to build up

• Chemical control

  Apply quinalphos 25 EC @ 750 ml/ha; dimethoate 20 EC @ 500 ml/ha; quinalphos 25 EC + dichlorvos 76 EC @ 750+250 ml/ha;

  Spray should be targeted to the shoots on and below the plucking table, and also the side

  Tea mosquito bug (Helopeltis theivora)

• Adults and nymphs punctures the plant tissues with needle like rostrum
• Suck the sap from buds,young leaves and tender stems
• Punctures appear as reddish brown spots

• Due to intensive feeding, leaves curl up, badly deformed, remain small 

•  Shoots dry up and crop loss is near total

  Adults black in colour, red thorax, black and white abdomen and greenish brown wings

• Active in early mornings and late evenings, more in moist shaded areas
• Seasonal prevalence largely dependent on weather factors
• Incidence of tea mosquito bug high during July–December and low during January-June

Control measures

• Cultural control

  Monitoring the infestation level in the field

  Black plucking, weed control

  Removal of stalks containing eggs while plucking

• Biological control

  Allow egg parasitoid (Erythmelus helopeltidis) to build up

• Chemical control

  Apply quinalphos 25 EC @ 750 ml/ha; chlorpyrifos 20 EC @ 750 ml/ha; fenthion 80 EC @ 200 ml/ha; quinalphos 25 EC + dichlorvos 76 EC @ 750+250 ml/ha

  Spray early mornings or evenings when these bugs are active