Leafhopper, Amrasca biguttula biguttula (Ishida) (Hom., Cicadellidae)

It is an important pest of several crops including tomato, cotton, okra, egg plant, potato, sunflower, cluster bean, castor, cowpea and wild plants including country mallow.

Adult is green, wedge shaped leafhopper.

It lays eggs singly within leaf veins.

Incubation period is 4-11 days. The nymph is light green translucent found between the veins of leaves on the under surface.

The nymphal period is 7 days. The life cycle is completed in 15-46 days.

Identification

Both nymphs and adults sucks the plant sap from the under surface of leaves.

The margin of the leaves start curling downwards and reddening sets in.

In the case of severe infestation leaves get a bronze or brick red colour which is typical “hopper burn” symptom.

The margin of the leaves get broken and crumble into pieces when crushed.

The leaves dried up and are shed and the growth of the crop is retarded.

ETL: 50 Nos. / 50 leaves

Symptoms of damage

1.Setup light trap to monitor the broods of leaf hopper to attract and kill

2.Release predators viz Chrysopa carnea

3.Early planting and close spacing of tomato reduces pest infestation particularly if the rainfall is heavy

4.Spray Thiamethoxam 25 WG @ 25g a.i /ha and NSKE 5% @ 25 kg/ha or 250 ml or Triazophos 40 EC 1500 ml/hectare

Management

Commonly known as cotton whitefly is found in most of the countries in tropics and subtropics.

Its main hosts are cotton, tobacco and some winter vegetables; including tomato, the infestation on these crops is sporadically severe.

White fly, Bemisia tabaci

Eggs are pear-shaped, light yellowish in colour, about 2 mm long and can be seen standing upright on leaves, being anchored by a tail-like appendage inserted into the stoma of leaves.

On hatching, the nymphs crawl a little, settle down on a succulent spot on the same leaf and never move again during that stage.

Nymphs are oval, scale-like and greenish-white in colour.

Adults are minute insects, about one mm long, covered completely with a white waxy bloom.

Incubation period is 3 - 5 days in summer extending up to 33 days during winter. Nymphal development takes 9 - 14 and 17 - 81 days in summer and winter, respectively and pupal period lasts for 2 - 8 days being longer during winter than in summer.

A life-cycle may be completed in as little as 14 days or it may even be prolonged up to 107 days. There are about 12 overlapping generations in a year.

SymptomsBemisia can cause economic damage to plants in several ways.

Heavy infestations of adults and their progeny can cause seedling death, or reduction in vigor and yield of older plants, due simply to sap removal.

Feeding by immature Bemisia, but not adults, has been associated with several developmental physiological disorders of plants.

Tomatoes that develop on plants that are heavily infested with whiteflies may incompletely develop external color, resulting in streaking.

Tomato leaf curling

Tomato leaf curling

Fruit damage

Silvery damage

Even if fruits appear normal externally, the internal tissue may be white, hard, and unripe.

Feeding by immature whiteflies causes newly developing leaves, but not the leaves on which they are feeding, to take on a silvery appearance due to the separation of the upper epidermis from the underlying cell layer. The resultant air space reflects light, causing the silvery color. Fruits that develop on silvered plants may be bleached, and are of lower quality grade.

Nature of damageBoth nymph and adult suck the sap from the infested parts.

This pest is more active during the dry season and its activity decreases with the onset of rains.

As a result of their feeding the affected parts become yellowish, the leaves wrinkle and curl downwards and are ultimately shed.

Besides damaging by feeding, these insects also exude honeydew which favours development of sooty mould.

In case of severe infestation this black coating is so heavy that it interferes with the photosynthetic activity of the plant resulting in stunted growth.

This whitefly also acts as a vector, transmitting the leaf curl virus disease, causing severe loss, as all the affected plants are necessarily to be uprooted and destroyed.

ManagementTimely sowing with recommended spacing, preferably wider spacing is essential and late sowing may be avoided.

Avoid the alternative, cultivated host crops of the white fly in the vicinity of the tomato crop.

Cultivation of brinjal, bhendi, cotton and tobacco near the tomato field may be avoided.

Adopt crop rotation with non-preferred host such as sorghum, ragi, maize etc., to check the build up of the pest.

Remove and destroy alternate weed hosts like Abutilon indicum, Solanum nigrum from the fields and neighbouring areas.

Field sanitation may be given proper attention.

Judicious irrigation management and nitrogenous fertilizer application may be followed to arrest the excessive vegetative growth and pest build up.Monitor the activities of the adult white flies by setting up yellow pan traps and sticky traps at 1 foot height and also in situ counts.

Collect and remove white fly infested leaves from the plants and those which were shed due to the attack of the pest and destroying them.

Apply methyl demeton 500 ml/ha in the early stage. Quinalphos 2 l (or) phosalone 2.5 l/ha in the mid and early stage of the crop.

The use of the synthetic pyrethroids should be discouraged / minimized to 2- 3 spraying in cotton to avoid the problem of whitefly.

Avoid repeated spraying of synthetic pyrethroids.

During the growing season, geminivirus-infected plants can be rogued out and destroyed.

Tomato thrips - Frankliniella schultzei

The tender foliage becomes spotted and pale and silvery sheens appear on the affecte leaves.

Flower thrips are common in the flowers of all summer pulses, as well as other crops, ornamentals and weeds.

Flower thrips feed and breed inside the flowers. Crops are at greatest risk during flowering and fruit set.

IdentificationAdults are 2 mm long, cigar-shaped and range in colour from yellow-orange to grey-black.

They have narrow wings folded along their back. Nymphs are similar in shape, pale yellow to orange-yellow, wingless and smaller.

Adults are fragile, slender, and minute and have heavily fringed wings.

A female lay on an average 50 eggs. Life cycle occupies 13 to 33 days. Females live longer than males and there are several overlapping generations in a year. ETL: 50 Nos. / 50 leaves

Damage symptom

Nymphs and adults feed in growing points and inside flowers.

Thrips damage can result in flower abortion and fruit distortion.

Is also vector that transmits the tomato spotted wilt virus causing bud nerosis.

The loss caused on this account is much more than by desapping caused by feeding of the thrips.

Collect and destroy the damaged leaves and twigs and uproot the diseased plants.

Use yellow sticky traps at 15/ha to attract and kill insects.

Release first instar larvae of Chrysoperla carnea @ 10,000/ha and encourage coccinellid predator.

Spray methyl demeton 25 EC 2 ml/lit, dimethoate 30 EC 2 ml/lit or endosulfan 0.7% or phosalone 0.9% to control vector.

Management

Mealy bug, Ferrisia virgataThe white tailed or striped mealy bug is a major pest of tomato.

It is a poly phagous pest and has a very wide host range of host plants including beans, cashew, cassava, and coffee, cocoa, citrus, cotton, groundnut, guava, jute, sugarcane, sweet potato and tomato.

The pest is found throughout the year, though less active during winter.

The population normally increases from February onwards and maximum activity is around middle of April and continues if the weather remains dry.

At times of heavy rains, or parasitisation, the population declines and again with the cessation of rains the population increases gradually till November and then again decreases.

Identification

Eggs are laid in clusters in cottony ovisac which remains concealed under the female body.

A single female lays 100 to 400 eggs. Eggs are pale yellow, cylindrical and about 0.3 mm long.

Freshly hatched crawlers are yellowish in colour and become pale white in 2 to 3 days.

Adults females are apterous, long, slender slightly oval (3.5-4.5/ 1.5 -2.0mm) covered with dusty white waxy secretion and having a pair of conspicuous and lomg glossy wax tassels at caudal end.

Reproduction is sexual as well as parthenogenitic. Incubation period is 15 minutes to 4 hours and the immature stages may last for 20 to 60 days in case of females. longevity of males is 1 to 3 days while the female live for 5 to 7 weeks.

Symptoms and Nature of damage

On hatching, the crawlers remain huddled together in cottony nest under the mother.

Later, these crawlers become active and wander about, moving swiftly till they find succulent spot where they puncture the epidermis of host plant, inject their toxic saliva and start sucking the cell sap.

The injury thus caused serves as entry for various disease- producing organisms (bacteria and fungi).

From second instar onwards, the nymphs secrete honey dew on which sooty mould may develop, which in turn hinders the photosynthetic activity of the plant resulting in stunted growth.

Pre adults and adults secrete a waxy mealy material.

Mealy bug on tomato plantsSpot like canker

Courtesy:http://agritech.tnau.ac.in

Management

•Uproot and destroy the diseased leaf curl plants

• Remove alternate weed hosts.

• Use nitrogen and irrigation judiciously.

•Use yellow sticky trap to attract and kill insects.

•Spray FORS 2% / neem oil 0.5% along with teepal 1 ml/lit (or) methyl demeton 0.25% (or) phasalone 0.7% (or) endosulfan 0.7% along with FORS 1%.

•Apply systemic insecticide in early stage and contact insecticide in later stage for vector control.

•Apply insecticide in the early morning as adults are less active.

•Encourage activity of parasitoids Eretmocerus mesii and predator coccinellids, Brumus and Chrysoperla.

Mites, Tetranichus cinnabarinus Tetranichus cinnabarinus commonly called red spider mite, is the most common and destructive species.

It has a worldwide distribution and is highly polyphagous having a very wide range of host plants.

Identification

Its eggs are globular in shape, about 0.1mm in diameter and whitish in colour.

Larvae are about 0.2mm in length and pinkish in colour.

Nymphs are greenish red in colour and about 3mm in length.Larvae and nymphs look alike in shape but can be easily easily distinguished as larvae have 3 pairs of legs while nymphs and adults have 4 pairs legs.

There are only two nymphal stages, protonymphal and deutonymphal.

Adults are ovate in shape, reddish- brown in colour and 0.4mm to 0.5mm in length with four pairs of legs.

Eggs hatch in 4 to 7days; larval development takes 3 to 5days; protonymphal and deutonymphal stages last for 3 to 4days each.

Longevity of adult mles and females is 4 to 9 and 9 to 18days respectively.

The females aestivate during summer in northern india, become active with the onset of monsoon and lay eggs parthenogenitically.

These unfertilised eggs give rese to males only, but the subsequent generations are sexual

The carmine spider mite normally completes a life cycle from egg to adult in about a week. All stages of this mite are present throughput the year.

Reproduction is most favorable when the weather is hot and dry.

Colonies of mites comprising larvae nymphs and adults are found feeding on ventral surface of leaves under protective cover of fine silken webs.

As a result of their feeding innumerable yellow spots appear on the dorsal surface of leaves and the affected leaves gradually start curling and finally get wrinkled and crumpled.

This in turn affects the growth and fruit formation capacity of the plants.

Management

Dusting with sulphur dust or spray application with wettable sulphur powder.

Spray dicofol 18.5 EC 2.5 ml/lit or wettable sulphur 50 WP 2g/lit

(ii) Spraying dicofol (kelthane 18.5 EC) 0.0185%. Spiromesifen 240SC@500ml/ ha

or

Propargite 570EC @1000ml /ha is very effective in managing this mite.

AphidsCotton aphid, Aphis gossypi and peach green aphid, Mysus persicae have been reported as minor pests of tomato plants, albeit the former is more common than the latter.

Nymphs and adults, often found in large number, suck the cell sap

IdentificationThe aphids are greenish brown, soft bodied and small insects.

The alate as well as apterous females multiply parthenogenitically and viviparously.

A single female may give birth to 8-22 nymphs in a day which become adult in about 7-9 days.

Yellowish or greenish brown nymphs found on the undersurface of leaves.

They are often attended by ants for the sweet honey dew secretion.

Winged forms may be seen under crowded conditions.

Symptoms and Nature of damage

It is a potential pest on cotton infesting tender shoots and under surface of the leaves.

They occur in large numbers suck the sap and cause stunted growth, gradual drying and result in death of the plants.

Development of black sooty mould due to the excretion of honey dew giving the plant a dark appearance.

ETL: 5% of infested plants.

Management

i. Release biocontrol agents viz., Coccinellid beetle Monochilus sexmaculatus and Coccinella septumpunctata and Aphelinus mali, A. flavipes. Predators - Phylloscopus tristis

ii. Monitor the nymphs and adults of early season sucking pests from the 14th day after sowing.

iii. Spray any one of the following insecticides / ha to control aphids.

Methyl demeton 500 ml, dimethoate 500 ml/ha (spray fluid 500 l/ha)

iv. Spray monocrotophos @ 1000 ml/ha and NSKE 5% @ 25 kg/hav. Spray Profenofos 50 EC @ 1.5 l/ha