Potato

Insect Management

Introduction Green Leaf Hopper Green Peach Aphid Hadda Beetles Greasy Cutworm Tobacco Caterpillar Potato Tuber Moth Whitefly

Introduction

  • In India, potato is grown in tropics as well as in sub-tropics in the cool season.
  • About 86% of the crop is grown in the plains during under short-day conditions, about 8% in the hills during summer under long day conditions and around 6% in the plateau during the rainy season.
  • It is a staple food of common masses in India.
  • Though India is the largest producer of potato yet its productivity is lower as compared to potato producing countries of Europe.
  • One of the major constraints of low productivity are the insect pests.
  • About fifty insect pests in India have been reported attacking potato crop directly or indirectly.
  • Potato crop is infested about by one dozen pests which are listed in table - I.
  • The important pests of the autumn crop are jassids, aphids, tobacco caterpillar & hadda beetle.
  • In the case of the spring crop, besides aphids, the other most important pests are cut worms.
  • A brief descriptions about their life histories & control measures etc is described as under:

Important Insect Pests of Potato

Common Name
Scientific Name Plant Injury
Period of activity
Cutworm Agrotis Ipsilon Larvae cut seedlings at ground level Feb to March
Tobacco Caterpillar Spodoptera litura Larvae feed on foliage Sept - Oct&March - April
Hadda beetles Epilachna vigintiocto Punctala Adults / Grubs feed on foliage Sept to Oct
Hphids Myzus persicae
Aphis fabae
Aphis gossypae
Suck plant sap & myzus persicae Vector of viral diseases Nov to March
Green Leaf hopper Amrasca biguttula biguttula Sap sucker, infest leaves & causes hopper burn Sept to March
Whitefly Bemisia tabaci Leaf curling & suck Plant sap October & March
Potato tuber Moth Phthoriniaea 0perculella Larvae infest leaves & tubers particularly during storage Sept - March

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Green Leaf Hopper

Amrasca biguttula (Ishida)
(Hemiptera; cicadellidae)

  • Jassid is the most destructive pest of many plants including Okra, brinjal, potato and cotton etc. It causes damage to potato in autumn season

Identification

Adult

    It is a wedge shaped and pale green insect of about 3.5 to 5mm length having a black spot on each transparent fore wing. It turns reddish brown during winter.

Nymph((fifth stage)

  • Pale-green, wedge shaped and its winged pads extend up to the fifth abdominal segment.

Egg

  • Elongated yellow-white egg is deposited in leaf vein. It becomes greyish yellow before hatching.

Life history

  • The female Jassids lay about 15 eggs on the underside of leaves embedding them into leaf veins.
  • The eggs hatch in 4-11 days
  • The nymphal stage is complete in 7-21 days.
  • Winged adults live for 35-50 days
  • This pest completes seven generations in a year.

Seasonal history

  • Jassid breeds practically through out the year, but during the winter months only adults are found on potato, brinjal and tomato, etc.

Ecology

  • Temperature 270 to 360 C and relative humidity below 75% favors the multiplication of Jassid.

Nature and symptoms of damage

  • Both nymphs and adults of Jassids suck plant sap as a result of their severe attack, the leaves curl, turn pale, bronze and dry up.

Control measures

  • Spray the crop with 300 ml of rogor 30EC (dimethoate) or metasystox 25EC (methyl-demeton) or 75 ml of dimecran 85SL ( phosphomidon) in 80-100 liters of water per acre.
  • If necessary repeat the spray after 10 days.

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Green Peach Aphid

Myzus persicae (Sulzer)
(Hemiptera; Aphididae)

  • During winter and spring season, the potato is attacked by various aphid species like M.persicae, Aphids gossyppi and A. fabae. Out of them m. persicae causes serious damage to potato crop by transmitting various viral diseases

Identification

Winged Adult

  • It has black body with transparent wings.
  • The abdomen has one or two transverse bands and four lateral dark spots.

Wingless Adult

  • It is shining green in colour.
  • The cornicles are medium in length, slender and slightly swollen in the middle.

Nymph

  • It resembles wingless adult but the size is small.

Life-history

  • The pest passes winter in egg stage on the bark of Prunun Spp. (Peach, plum, apricot etc.)

Seasonal-History

  • During spring season wingless forms are produced within a few days from over wintering eggs.
  • Partheno genetic females give rise to two similar generations.
  • In December, winged germs appear on potato crop.
  • Apterous females are formed on potato, till end of March.
  • With rise of temperature, winged forms are produced which migrate to hill areas again to primary hosts.
  • Thus this pest appears in plain areas in winter while in the hills it appears in summer and autumn season.

Ecology

  • A relative humidity of 66 + 2.8% and 11 -140 C temperature are ideal for development of this aphid.
  • Its population sharply decreases with increase in RH over 73 percent.
  • The build up of aphid population on potato in plain area, is governed by arrival of winged forms and availability of host and suitable environment.

Nature and symptom of damage

  • Aphids suck sap of plants, as a result of which leaves turn pale and dry up.
  • This pest also transit various viral diseases like leaf roll, virus Y and virus A to potato plants.
  • These viruses cause heavy reduction in the yield besides the degeneration of the seed stocks.

Control Measures

  • Spray 300 ml of Metasystox 25EC (Methyl demeton) or 200 ml of Rogar 30EC (Dimethoate) or 75 ml of Dimecran 85SL ( phosphamidon) in 100 liters of water.
  • In case of seed crop, apply 5 kg of Thimet 10G (phorate) to the soil at the time of the first earthing up.

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Hadda Beetles

Epilachna duodecastigma (mulsant)
E. Vigintioctata (Fabricius)
(Caleoptera; coccinallidae)

  • Two species of hadda beetles attack different solanaceous vegetables, like brinjal, tomato and potato.

Identification

Adults

  • Beetle of Epilachna viginatioctopunctata is about 8-9 mm in length and 5-6 mm in width. Its colour is deep red and usually has 7-14 black spots on each elytron whose tip is some what pointed.
  • Beetle of E. dudodecastigma is deep copper-coloured and has six black spots on each elytron whose tip is more rounded.

Egg

  • Yellow, cigar shaped eggs, mostly laid in batches (5-40) each on the underside of leaves.

Grubs

  • Grubs of both the species are about 6mm long, yellowish in colour and have six rows of long branched spines.

Pupa

  • The pupae are darker and , are found fixed on the leaves, stems and most commonly, at the base of the plants.

Life-history

  • A female beetle lays about 300 small cigar-shaped yellow eggs in clusters of 10 to 50 on the under surface of potato leaves.
  • Eggs hatch in about 5 days into small, yellow grubs, covered with hairy spines.
  • The grubs feed on the lower epidermis of leaves are full grown in 7 to 18 days.
  • The pupal stage lasts 5 to 14 days.

Seasonal-Occurrence

  • It passes the winter as a hibernating adult among heaps of dry plants or in cracks and crevices in the soil.
  • The pest passes through several broods from March to October and its population is at a maximum at the end of April or in early May.
  • During the hot and dry months, the number declines greatly but the population again builds up in August.

Nature and Symptoms of damage

  • Both the adults and grubs cause damage by feeding on the upper surface of leaves.
  • The leaves present a lace-like appearance.
  • The infected leaves turn brown, dry up and fall off and completely skeletonize the plants.
  • A severe infestation may cause up to 75 percent loss in yield.

Control Measures

Both adults beetle and grubs can be killed by the following management practices

  • On a small scale, hand collection of grubs and adults should be done.
  • Conservation and augmentation of natural parasitoids viz. Pediobius foveolatus, Pleunotrogrus faveolatus and Tetrastichus sp.
  • Use of Bacillus thuringensis is effective.
  • Application of Neem, Mahua, ground nut cakes are efficient in suppressing the pest population.
  • Spray of Malathion 50 EC in 200 liters of water per acre provides up to 82 percent kill of this pest.

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Greasy Cutworm

Agrotis ypsilon Rott (Lepidoptera ; Noctuidoe)

  • The greasy cutworm has been reported from almost all the potato-growing regions of Northern India.
  • This polyphagous has been reported feeding on potato, tobacco, peas, wheat, lentil, mustard, linseed, maize, sugarcane, cucurbits, vegetable seedlings and several weeds.

Identification

Adult Moth

  • It measures about 25 mm from the head to the tip of the abdomen.
  • And looks dark with some grayish patches on the back and dark streaks on the forewings.

Eggs

  • Creamy white, dome-shaped eggs

Larvae

  • Newly emerged young larva is yellow in colour, 1.5 mm long with a shiny, black head and a black shield on the prothorax.
  • The full-grown larva is about 42-45 mm long and is dark or dark brown with a plump and greasy body.

Pupa

  • Dark brown pupae are found in earthen cells lying underground in the potato fields.

Life-Cycle

  • Moths come out at dusk and lay eggs (200-350) in clusters of about 30 each, either on the under surface of the leaves of host plants or in the soil.
  • The larval stage varies from 30-34 days, in February-April.
  • Pupation takes place underground in a earthen chamber is completed in 10 to 30 days.
  • The moths usually emerge at night.
  • The life cycle is completed in 48 to 77 days.
  • This pest generally completes three generations in a year.

Seasonal Occurrence

  • This pest is active from October to April in plain area of Punjab and probably migrates to the mountains for further breeding during summer.
  • The moths appear in plains in October & start breeding on number of host plants till March.
  • It suddenly disappears with the onset of summer during April.

Ecology

  • It is a pest of winter season.
  • Both adults caterpillars become active at night.
  • Caterpillars during the daytime, hide in crack and crevices in the soil.
  • Persistent dry weather with lesser or no rainfall, reduced humidity & 16 deg-23deg C temperatures favor the development of cutworm.

Nature and Symptoms of Damage

  • The young larvae feed on the epidermis of the leaves.
  • Older larvae come out at night and fell the young plants by cutting their stems, either below the surface or above the ground and thus affect their growth, vigor and yield.
  • They also damage the tubers by eating away part of them. Up to 40% of the tubers, in badly affected fields may be damaged by this pest.

Control Measure

Following measures will help in minimizing the infestation this pest

  • Break the sods in the fields.
  • Flood the infested fields.
  • On a small area, collection of caterpillars from soil around the plants can be done.
  • Collection of moths in the light traps.
  • Use of chlorpyriphos 20 EC @ 2 l / ha to the soil before planting potato tubers.

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Tobacco Caterpillar

Scientific Name : Spodoptera litura (Fabricius)

  • This polyphagous feeds on tobacco, potato, tomato, cabbage, cauliflower, peas, cowpea, and castor.

Identification

Moth

  • It is dark-coloured and has certain patterns and white-wavy markings on the fore wings.
  • It measures about 22mm in length.

Egg

  • Dark green and circular shaped eggs are laid under side of leaves.

Caterpillar

  • It is velvety black with yellowish-green dorsal stripes and lateral white bands.

Pupa

  • Dark-brown pupae are found in silken bodies.

Life-history

  • The moths are active at night.
  • After mating female moth lays eggs (300) in clusters, which are covered over by brown hairs.
  • The eggs hatch in 3-5 days.
  • The larvae are full-fed in 15-30 days.
  • The full-grown larvae enter the soil and complete pupil stage in 7 to 15 days.
  • Moths on emergence live for 7-10 days.
  • The whole-life-cycle is completed in 32-60 days.
  • The pest has eight generations in a year

Seasonal-history

  • This pest breeds throughout the year on different host plants.
  • During winter, its development is considerably retarded.

Ecology

  • Moderate temperature and humidity is quite favorable for its multiplication.

Nature and Symptoms of damage

  • The young larvae first feed gregariously and scrape the leaves.
  • Older larvae spread out and may completely devour the leaves resulting in poor growth of plants.

Control-measures

  • The leaves, which have egg masses and young larvae in the gregarious phase, should be plucked and destroyed.
  • The pest can be killed by spraying 300-400 ml of Ekalux 2 S EC (quinalphos) or Thiodan 35 EC (endosulfan or Diptrex 50 E C (tri chlorphon) in 100 liters of water per acre.

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Potato Tuber Moth

Gnorimoschema opercullella (Zeller)
(Lepidopterab ; Gelechiidae)

  • This native of South America and was introduced in India in the beginning of the 20th century.
  • It is distributed in Bihar, Karnatak, Maharashtra, Himachal Pradesh, Kumaon hills of west Bengal, Nilgiris (Tamil Nadu), Maharashtra and submountainous areas of Punjab.
  • This pest occurs especially in hot and dry climates.
  • It is destructive to potatoes and also attacks tomato, egg-plant (brinjal), tobacco and Solanaceous weeds.

Identification

Moth

  • The adult is a very small narrow-winged nocturnal moth, about 12 mm across the wings when spread.
  • It is grayish brown with mottling of dark brown.

Eggs

  • The eggs are pale white in color, spherical in shape.

Larva

  • Pinkish white or greenish caterpillars with dark-brown heads. It is about 20 mm in length.

Pupa

  • It pupates in a grayish silken dirt-covered cocoon, which is about 13mm in length.

Life history

  • The pest is active through out the year in the plains of northern India.
  • A female moth lays from 50 to 200 eggs on the underside of leaves or on the eyes of exposed tubers.
  • The eggs hatch in 3 to 4 days. The young larvae first produce blotch mines on leaves but subsequently, they work their way into the stems and exposed tubers.
  • The larval stage is completed in 2 to 3 weeks during summer season.
  • The mature larva pupates in a silken cocoon and the moth emerges in 7-10 days.
  • The whole life cycle is completed in about one month and they are usually 8-13 generations of this pest in a year.

Control

  • Construct potato stores away from the fields
  • Cover tubers lying in stores with a thin (2.5-5.0 cm) layer of dry sand. The surface of sand cover of the potatoes should be dusted with one percent malathion dust.
  • Carry out disposal of infested potatoes.

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Whitefly

Bemisia tabaci genn
(Hemiptera; Abyrodidae)

  • Apart from cotton, this pest also feeds on potato, brinjal, okra, cabbage, cauliflower and some weeds.

Identification

Adult:

  • It is small winged insect having light yellow body of 1.0-1.5mm length dusted with a white waxy powder.
  • Wings are pure white and has prominent long legs.

Nymph

  • It is louse like, sluggish creature having pale-yellow body.

Pupa

  • Convex in shape and possesses deep yellow patches on the abdomen.

Egg

  • It is smooth, sub elliptical, stalked at broader basal end.
  • Its colour is light yellow, when freshly laid, turn dark brown later on.

Life history

  • The female white flies lay eggs singly on the underside of the leaves.
  • The eggs hatch in 5-17 days
  • The nymphal stage lasts 14 to 81 days.
  • In 2-8 days, the pupae change into white flies
  • The life cycle is completed in 14-122 days
  • Eleven generations of this pest are completed in a year.

Seasonal history

  • This pests breeds through the year and all the development stages are noticed in different host plants.
  • During cold season, most adult white flies are present

Ecology

  • The temperature of 28-360 C and 62-92% relative humidity and scanty rainfall during August to January are quite favorable for this pest.

Nature and symptoms of damage

  • Nymphs suck sap from the leaves and lower their vitality.
  • Sooty mould develops on affected leaves and the affected plants look sick.
  • The growth of the whitefly heavily attacked potato crop is arrested

Control measures

  • This pest can be controlled by spraying 300 ml of rogor 30EC (dimethoate) or metasystox 25EC (methyl-demeton) or 75 ml of dimecran 85SL ( phosphamidon) in 80-100 liters of water per acre.

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