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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.