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INSECT-PEST & DISEASES OF

ROOT CROPS ALONG WITH THEIR

PHYSIOLOGICAL DISORDERS

Presented By:-Kuldeep Garwa

Insect-Pest of

Root crops

Beet PestsBeet Leaf Miner (Pegomyia hyocyami ) :• The adult female lays eggs on the underside of the

leaves.• The maggots after hatching from the eggs attack tender

leaves and feed in the epidermal layers of the leaf by making serpentine mines in which air gets trapped and gives them silvery appearance.

• Such leaves gradually dry and die away.Control:-Destruction of all fallen leaves and other plant

debris.• Spraying with Methyl Demeton (0.03%) and

Phosphamidon (0.035%) is effective.

Beet Leaf Miner

Web Worms (Hymenia sp. or Loxostege sp.) :

• Eggs are laid in clusters on the undersurface of the leaves and held together by gelatinous glue.

• Green caterpillars web up the leaves and live inside the knotted mass.

• Flowering and pod formation is adversely affected.

Control: • Removal and destruction of webbed

bunches of leaf help to check the further spread of the disease.

• Spraying with Rogor (1 ml/litre of water) is effective.

Semiloopers (Plusia spp.) :• The green caterpillars voraciously feed on the foliage

damaging green foliage badly.

Control: Hand picking the larvae and spraying the crop with Carbaryll (0.1%) controls the pest.

Carrot PestsCarrot Rust Fly (Psila rosae):• The larvae mine in the roots, causing holes that are

subject to rot by secondary organisms.• Heavy maggot feeding is indicated by drooping,

discolored foliage.Control: Cultural methods such as deep plowing,

rotation of crops, and destruction of wild hosts help to check the pest population.

• Soil application of Carbofuran at a depth of 10-15 cm effectively controls the pest.

Carrot Rust Fly

Thrips (Thrips tabacii):• Adults and larvae suck the cell sap from the leaves of

the plants. • White blotches appear on leaves.Control: Spraying of insecticides like Monocrotophos

(0.1%) or Malathion (0.05%) offer a good control.Nematode (Heterodera carotae, Meloidogyne sp.)• Nematodes can cause serious problems in carrots and

result in substantial yield losses.• Nematodes can cause roots to become forked and

therefore unmarketable.Control: Soil treatment with Nemagon is effective in

reducing the nematode population.

Nematode Effected Carrots

Turnip Pests• Aphids (Myzus persicae,

Lipaphis erysimi)• The nymphs and adults suck

the cell sap.• Affected parts become

discolored and malformed.• High humidity favours rapid

multiplication of this pest.

• Control: Spraying of Monocrotophos (0.05%) or Malathion (0.1%) at 10-15 days interval.

Radish PestsAphids (Myzus persicae, Brevicoryne brassicae,

Lipaphis erysimi)• The nymphs and adults suck the cell sap and devitalize

plants.• Affected parts become discolored and malformed.• High humidity favour rapid multiplication of this pest.Control: Spraying of Monocrotophos (0.05%) or

Malathion (0.1%) at 10-15 days interval.• To prevent recurrence of the pest granular insecticides

like Phorate @ 1.0 kg a.i./ha should be applied to soil.

Mustard Sawfly (Athalia proxima)• The pest attack is observed in the vegetative and

flowering stage of the crop.• The adult female lays eggs inside the leaf tissue. • The grubs after hatching from the eggs feed on the

leaves by making small holes.Control: Hand picking of larvae when the area

involved is small, or spraying with Malathion 50 EC (1ml/litre of water) twice at an interval of 10 days is recommended.

Diseases of

Root crops

BeetLeaf Spot (Cercospora beticola) :• This is a commonly occurring disease on foliage of beet

roots.• High humidity usually favours the spread of this disease.• Numerous small circular spots appear on the leaf surface.• The spots increase in size, becoming brownish or purplish

in color.Control: • Removal and destruction of affected plants.• Spraying with Copper Oxychloride (0.3 %) thrice at an

interval of 15 days.

Leaf Spot

Downy Mildew (Perenospora schachtti) :

• The disease is mostly prevalent during the cooler months.

• Symptoms appear as irregular greasy greyish areas on the leaves.

• Under moist conditions, these areas expand rapidly and a white powdery growth appears on the lower surface of the affected leaves.

• Affected leaf dries and shrivels quickly.Control: • Preventive measures• Seed treatment with Thiram (2.5-3 g/kg of seed)• Spraying with Dithane Z-78 (0.3 %) thrice at an

interval of 15 days.

Mosaic :• The disease is normally transmitted and spread by aphids.• Symptoms appear as conspicuous mottling with chlorotic,

zonate ring spots on the leaf surface.• Virus infected plants remain stunted and may lose some

leaves.

• Control: Destruction of infected plants and controlling the aphid population by spraying Malathion (2ml/litre of water) prevents the spread of the disease.

Curly-top :• This disease is transmitted by beet leaf hoppers. • Generally, mottling is absent, but infected plant parts

may become distorted through curling, twisting, rolling, stunting, etc.

• Leaves become thickened and leathery.Control: • Regulating the time of planting in order to avoid the

main flights of the beet leafhopper; • Use of barriers of trap crops and early removal and

destruction of infected plants.• Spraying Malathion (2ml/litre of water) controls the

population of beet leaf hoppers.

Beet Yellows :• This disease is transmitted mainly through aphids.• The important symptoms of the disease include

yellow spots on the young leaves in the initial stages of infection.

• As the disease progresses, the leaves exhibit irregular yellow patches alternating with normal green colour of the leaves.

Control: Control measures include removal of infected plants and weeds from the field.

• The disease incidence can be minimised by controlling the population of aphids by spraying Oxydemeton Methyl 25EC (2ml/litre of water).

Purple Leaf of Beet :• This viral disease is caused by a strain of tobacco

mosaic virus (TMV).• The infected plants are stunted.• Few leaves develop minute necrotic lesions all

over the lamina.Control: Removal and destruction of virus-

infected plants and weed hosts helps in minimising disease.

Purple Leaf of Beet

Radish DiseasesAlternaria Blight (Alternaria raphani):• Symptoms of the disease first appear on the leaves in

the form of small, yellowish, slightly raised lesions.• Lesions appear later on the stems and seed pods. • Infection spreads rapidly during rainy weather.Control: Though hot water treatment of the seed

kills the fungus, use of diseases- free seeds is recommended.

• Regular spraying with Difolatan (0.3%) or Dithane M 45 (0.2%) or Ridomil (0.1%) controls the disease effectively.

Alternaria Blight

White Rust (Albugo candida):• Disease attacks the leaves and

flowering shoots.• White powdery substance in

patches is observed on the under surface of the leaves.

Control: Clean cultivation and use of resistant varieties help to prevent the disease.

• Regular spraying with Dithane Z 78 (0.2%) effectively control.

Root Rot of Radish (Erwinia rhapontici)• Symptoms appear as rotting of pith tissues resulting in

cavity formation and wilting of plants.• The disease spreads when the roots are transplanted for

seed production.Control: Dipping of the seeds in a solution of Agrimycin-

100 (100 ppm) at the time of sowing is effective in checking the disease.

Radish Mosaic Virus (RMV):• The symptoms first appear as small, circular to irregular,

chlorotic lesion in between and adjacent to the veins.• It is transmitted through aphids.Control: Spray of Dimecron (0.05%) or Monocrotophos

(0.05%) at 10 days interval.

Radish Phyllody:• The disease is transmitted by

jassid Orosius albicinctus.• The symptoms of the disease

appear at the time of flowering when all the floral parts become green violet and leafy.

• The sepals and petals become green thick knob headed leaves.

Control: One or two sprays of Monocrotophos (0.05%) or Phosphamidon (0.05%) .

Turnip Diseaseso Alternaria Leaf Spot

(Alternaria spp.): • Symptoms of the disease first appear

on the leaves of seed stem in the form of small, yellowish, slightly raised lesions.

• Lesions appear later on the stems and seed pods.

Control: Hot water treatment.• Regular spraying with Difolatan

(0.3%) or Dithane M 45 (0.2%) or Ridomil (0.1%) controls the disease effectively.

White Rust

o Turnip Phyllody:• The disease is transmitted by jassid.• The symptoms of the disease appear at the time of

flowering when all the floral parts become green violet and leafy.

Control: One or two spray of Monocrotophos (0.05%) or Phosphamidon (0.05%) or Oxydemetan Methyl (0.02%) is effective.

o Turnip Crinkle Virus:• The disease is characterized by crinkling of leaves.• The infected leaves show rugged, appearance,

develop yellow patches and are brittle. • Later on, the affected leaves begin to die and wither

away.Control: Use of resistant varieties.• Adopting sanitary measures including the eradication

of susceptible weeds and susceptible volunteer crop plants.

Turnip mosaic virus

Carrot DiseasesCercospora Leaf Blight (Cercospora carotae):• The disease produce severe blighting if wet weather is

prolonged during the growing season.• The symptoms first appear along the margins of the

leaves, often causing the leaves to curl.• Spots inside the leaf edges are small, roughly circular,

gray to brown with a dead center.Control:

• The use of disease-free seed.• Early applications of Foltaf (0.2%), Copper

Oxychloride (0.3%), effectively control.

Cercospora Leaf Blight

Alternaria Blight (Alternaria dauci):• Alternaria leaf spots first appear at the margin of the

leaflets and are dark brown to black and irregular in shape.

• As the disease progresses entire leaflets may shrivel and die, appearing scorched.

Control:• Seed treatment with Thiram (3g/kg of seed) is

effective.• Crop rotation and destruction of infected plant

material.• Fungicidal applications with Foltaf (0.2%), Copper

Oxychloride (0.3%) satisfactorily controls the disease.

Alternaria Blight

Powdery Mildew (Erysiphe polygoni):

• The symptoms appear as white powdery growth on the leaves and petioles causing the leaves to turn brown and wilt.

Control: Spraying Bavistin (0.1%) or Benlate (0.1%) at an interval of 8-10 days effectively controls the disease.

Watery soft Rot (Sclerotinia sclerotiorum):• The disease is present in soil or storage areas and

often shows up after the crop has been harvested.• Symptoms can be identified in the field as

characteristic white mold with black sclerotia present on the crown of infected carrots.

Control: Crop rotation, weed control (to improve air circulation), planting on raised beds, winter flooding all components are all necessary to reduce losses from this disease.

Watery soft Rot

Black Rot (Alternaria radicina):• This disease can be seed and soil-borne and is

characterized by a shiny black decay at the crown area and a greenish-black mold on the taproot.

• The infected tissue is greenish black to jet black due presence of masses of black spores.

• This disease affects the roots in the field well as in storage.

Control: • Proper field sanitation and practicing rotation helps to

keep the disease under control. • The root surface should kept dry and stored at 00C

with 95 % relative humidity.

Bacterial soft Rot (Erwinia carotovora p.v. carotovora and atroseptica):

• Bacterial soft rots of carrots occur only when soil conditions are wet or storage conditions are poor.

• Soft water-soaked, irregular lesions appear on the roots.

Control: • Planting on raised beds in poorly drained areas may

reduce bacterial infections.• Careful harvest handling, grading and sanitation are

the only ways to reduce the problem.

Bacterial soft Rot

Carrot Yellows• The affected leaves become yellow accompanied by

vein clearing.• Dormant buds in the crown grow out into chloratic

shoots, which give a withers broom appearance on the top.

• Size and quality of roots are reduced and malformed.• The internal texture of roots show marked changes.Control: • Weed control especially of those acting as alternate

host eliminates the disease.• Spraying insecticides to control the leaf hopper

population helps to reduce the disease attack.

Carrot Yellows

Physiological Disorders

of Root crops

Beet DisordersInternal Black Spot/ Brown Heart :• This disorder is caused due to Boron deficiency.• Boron deficient plants usually remain dwarf or

stunted.• The leaves are smaller than normal.• The growing points may die and decay.Control: Application of borax to the soil is

recommended. • The quantity of borax needed should be based on

nature of the soil and soil pH.

Carrot DisordersCarrot Splitting• Splitting or cracking of carrot is a major problem in

many carrot growing areas.• Additions of excess nitrogen can result in splitting of

carrots especially if rain or heavy irrigation occurs shortly after application.

Control: Nitrogen applications should be kept to a minimum during the early growing period.

• Heavy applications in the early part of the season can predispose carrots to more severe cold injury in cases of low temperatures.

Carrot Splitting

Cavity Spot• Cavity spot is characterized by

elliptical to irregularly shaped, depressed lesions oriented across the mature carrot tap roots.

• Lesions begin as pinpoint, sunken spots and generally enlarge as roots mature.

Control: • Older carrots are more susceptible

to infection.• Providing excess irrigation to the

crop should be avoided.

Carrot Forking

Bitterness• Pre-harvest stress (improper irrigation scheduling) or

exposure to ethylene from ripening rooms or mixing with commodities such as apples may cause bitterness.

Radish DisordersPore development or Pithiness• It is caused by excessive root growth in comparison

with the corresponding assimilation ability of leaf tissue.

• Physiologically, parenchymatous cells in root tissue are collapsed. 

• When harvesting is delayed, this disorder is more pronounced.

Control:To avoid the pore extent, harvesting should be done at appropriate time.

Elongated root or Forking• The disorder is due to the excess moisture during the

root development of radish and carrot.• It also occurs in heavy soil due to the soil

compactness.• Un-decomposed organic manure favours elongated

root in radish.Control:• It can be corrected by reducing the moisture from the

field, by balanced irrigation and also by sowing the radish and carrot in sandy loam or light soil having soils of loose and friable in nature.

Radish forking

Bolting• Development of seed stalk without proper

development of economically important / edible vegetative part is termed as bolting.

• Radish is a seed vernalizing crop in response to low temperature. 

• The degree of bolting ability has been studied because of its disadvantage in cultivation, and breeding research has been directed toward late bolting.