Integrated Pest Management

Alternaria leaf spot

Causal Organism

Alternaria alternaria A. tenuissima

Damage

• The disease occurs rarely on green gram and can be seen in all the seasons.
• Initially, small, circular brown spots appear on the leaf surface.
• Gradually, the spots become dark brown with concentric circles.
• As the severity increases, the spots enlarge and the concentric rings become clearly visible.
• Affected portions in the leaf get separated and fall down resulting in shot holes.

Survival & Favourable Conditions

• The pathogen survives through spores (conidia) or mycelium in diseased plant debris or weed host.
• Moist ( more than 70% relative humidity) and warm weather (12-25 C temp) and intermittent rains are favours disease development.

Cultural Control

• Field sanitation

Chemical Control

• Seed treatment with Thiram 2.5 g/kg seed.
• Spray the crop with Mancozeb 75 % WP at the rate 2 gm per litre.
• If the infection persists then repeat the spray after 15 days interval.
  OR
• Three or four spray of carbendazim 7-7.5 g/litre or Mancozeb
  (Dithane M 45) 75% WP.
  OR
• Zineb at 2 g/litre per ha just at the appearance of the disease.

Anthracnose

Causal Organism

Colletotrichum lindemuthianum, C. capsisi

Damage

• The fungus attacks all aerial part parts and at any stage of plant growth.
• Symptoms are circular, black, sunken spots with dark center and bright red orange margins on leaves and pods.
• In severe infections, the affected parts wither off.
• Seedlings get blighted due to infection soon after seed germination.

Survival & Favourable Conditions

• The pathogens survive on seed and plant debris
• Disease spreads in the field through air-borne conidia.
• The disease is more sever in cool and wet seasons.

Cultural Control

• Hot water treatment at 54 degree centigrade for 10 min.
• Use disease free seed.
• Follow crop rotation

Chemical Control

• Spray mancozeb 0.3% or carbendazim 0.5/Litre.

Bacterial Leaf Blight

Causal Organism

Xanthomonas phaseoli

Damage

• It is characterized by many brown, dry and raised spots on the leaf surface.
• When the disease is severe several such spots coalesce, the leaves become yellow and fall off prematurely.
• The lower surface of the leaf appears red in colour due to the formation of raised spots.
• The stem and pods also get infected.

Survival & Favourable Conditions

• The bacterium is seed-borne and through vines grow perennially.
• Rain splashes play an important role in the development and spreading of the disease.

Cultural Control

• Grow tolerant varieties of the disease.
• Use disease free seed

Mechanical Control

• Destruction of debris and stubbles.

Chemical Control

• Soaking the seed in 500 ppm Streptocycline solution for 30 min. before sowing followed by two sprays of Streptocycline combined with 3 g of Copper Oxychloride per litre at an interval of 12 days is recommended.

Cercospora leaf spot

Causal Organism

Cercospora canescens

Damage

• This is an important disease of green gram and is usually occurs in a severe form, causing heavy losses in yield.
• Spots produced are small, numerous in number with pale brown centre and reddish brown margin. Similar spots also occur on branches and pods.
• Under favourable environmental conditions, severe leaf spotting and defoliation occurs at the time of flowering and pod formation.

Survival & Favourable Conditions

• The fungus is seed-borne and also survives on plant debris in the soil.
• High humidity favours disease development.

Cultural Control

• Cultivate resistant varieties.
• Intercrop the moong with tall growing cereals and millets.
• Follow clean cultivation.
• Use disease free seed.
• Maintain low crop population density and wide row planting.

Biological Control

• The crude extracts of cassava, spiny amaranth, poinsettia, ipil-ipil, alascuatro, tagetes, garlic, mayana and zinger are applied for controlling the disease effectively.

Mechanical Control

• Mulching reduces the disease incidence resulting in increase yield.

Chemical Control

• Cercospora leaf spot was effectively controlled by only a spray of  Carbendazim (0.05%) at 30 days after sowing.

Corynespora Leaf Spot

Causal Organism

Corynespora cassiicola

Damage

• By this disease yields decrease drastically.
• Symptoms of this disease develop on leaves when the crop reaches flowering stage.
• Lesions begin as dark reddish brown circular spot usually on the upper surface of the leaf and they expand to become larger spots.
• In advanced stages the spots coalesce to form patches. Shot-holing and severe defoliation is a marked symptom in advanced stages of infection.

Survival & Favourable Conditions

• The fungus is seed-borne and can survive on host debris for two years.

Cultural Control

• Use tolerant varieties LBG 167.

Chemical Control

• Corynespora leaf spot was effectively controlled by only a spray of

Leaf Curl

Causal Organism

Leaf Curl Virus

Damage

• An important and potential killer of green gram plants, more severe in Kharif season.
• The earliest symptoms appear on youngest leaves as chlorosis around some lateral veins and its branches near the margin.
• The leaves show curling of margin downwards.
• Some of the leaves show twisting.
• The veins show reddish brown discolouration on the under surface which also extends to the petiole.
• Plants showing symptoms within 5 weeks after sowing invariably remain stunted and majority of  these die due to top necrosis within a week or two.
• Plants infected in late stages of growth do not show severe curling and twisting of the leaves but show conspicuous venial chlorosis any where on the leaf lamina.

Survival & Favourable Conditions

• The disease develops in the fields mainly through seed or rubbing of diseased leaves with the healthy ones.

Cultural Control

• Timely sowing.
• Complete field and crop sanitation.
• Take control measures for thrips.

Chemical Control

• The virus is transmitted by thrips, Scirtothrips dorsalis, and hence can be managed by controlling thrips by spraying 1 g Acephate or 2 ml Dimethoate per litre.

Leaf Web Blight

Causal Organism

Rhizotonia solani

Damage

• Symptoms appear on leaves initially as small,  water-soaked, light green lesions of various shapes.
• Spots that are formed on older leaves gradually increase in number and size attaining reddish brown colour and spread to young leaves also.
• Numerous white sclerotia are formed in the pink coloured web formed by the fungul mycelium.
• Affected leaves shed and drop. As a result of  shortening of the branches, yields are drastically reduced.

Survival & Favourable Conditions

• The pathogen is soil-borne and initial inoculum comes from soil during the rains.
• The disease also spread from diseased plants to healthy by contact.
• Moist weather and high temperatures favours the spread of the disease.

Cultural Control

• Follow crop rotation
• Adjust sowing time in such a way that it should not be timed with main rainfall
• Keep the crop weed free.
• Good soil drainage and thin plant density reduces the incidence of disease.

Mechanical Control

• Destroy diseased plant debris.

Biological Control

• Use Trichoderma viride as biocontrol agent.

Chemical Control

• Spray Mancozeb/ Copper Oxychloride at 3 g per litre or Carbendazim/ Thiophanate-methyl at 1 g per litre is recommended at the time of podding when the disease disappears on the crop.

Macrophomina Blight

Causal Organism

Macrophomina phaseolina

Damage

• In rice fallows, symptoms appear on 4 weeks  old green gram crop as raised white cankers at the base of the stem.
• These enlarge gradually and turn as raised brown streaks spreading upwards.
• Plants are stunted and leaves are dark green, mottled and reduced in size.
• Normal leaves on the affected plants drop suddenly and dry.
• Flowering and podding are greatly reduced.
• When the affected plants are split/open vertically from the collar downwards, reddish discolouration of the internal tissues is clearly visible while the internal root tissues appear white.

Survival & Favourable Conditions

• The pathogen can survive through seed, soil, diseased plant parts and host plants.
• The severity of the disease increases with the increase in temperatures.
• Fungus survives in upper layers of the soil and enters plant through stem.

Cultural Control

• Cultivate resistant varieties.
• Deep ploughing in summer.
• Soil solarization.
• Follow crop rotation
• Soil amendment with farm yard manure is helpful in reducing the incidence of the disease

Mechanical Control

• Destroy the diseased plant debris by burning of burying in the soil.

Chemical Control

• Seed treatment with carbendazim + Thiram 1:2.

Mungbean yellow mosaic virus

Causal Organism

Mungbean yellow mosaic virus

Damage

• The disease is prevalent on green gram.
• Initially mild scattered yellow spots appear on young leaves. Spots gradually increase in size and ultimately some leaves turn completely yellow.
• Infected leaves also show necrotic symptoms.
• Diseased plants are stunted, mature late and produce very few flowers and pods.
• Pods of infected plants are reduced in size and turn yellow in colour.

Survival & Favourable Conditions

• The disease is transmitted by whitefly, Bemisia, tabaci.

Cultural Control

• Grow resistant varieties to yellow mosaic.
• HUM 8, HUM 9, PDM 84-139, Pusa Bold 1, Pusa Bold 2 and K1284 varieties are resistant to yellow mosaic virus.
• The crop must be sown timely.
• The spacing between the lines should be maintained at 30 to 40 cms.
• Only certified seeds should be used for sowing.
• If the seeds are not treated than seed treatment should be done.
• In endemic areas, only tolerant and resistant varieties should be used.
• Weeds plants should be rouged out at their inception.
• Insect, fungal and nematode vectors should be controlled using suitable pesticides.
• Control white fly as it spreads the virus.

Mechanical Control

• Rogue out MYMV infected plants early in the season to eliminate the source of inoculum.

Chemical Control

• Apply 10% phorate granules at the rate of 1kg/ha in the soil before sowing.

Powdery Mildew

Causal Organism

Erysiphe polygoni DC

Damage

• Powdery mildew is one of the widespread diseases of several legumes in green gram.
• White powdery patches appear on leaves and other green parts which later become dull coloured. These patches gradually increase in size and become circular covering the lower
  surface also.
• When the infection is severe, both the surfaces of the leaves are completely covered by whitish powdery growth. Severely affected parts get shriveled and distorted.
• In severe infections, foliage becomes yellow causing premature defoliation. The disease also creates forced maturity of the infected plants which results in heavy yield losses.

Survival & Favourable Conditions

• The pathogen has a wide host range and survives in oidial form on various hosts in off-season.
• Secondary spread is through air-borne oidia produced in the season.

Cultural Control

• Use resistant varieties
• The seeds must be sown early in the month of June to avoid early incidence of the disease on the crop.

Chemical Control

• Powdery mildew could be controlled by spraying Carbendazim (0.05%) and Penconalzole (0.05%)
• Two spray of Carbendazim or Thiophanate Methyl 1 g ml or Tridemorph 1 ml per litre, one dose immediately after the disease appearance and the second dose 15 days later effectively manage
  the disease
   

Root Rot and Leaf Blight

Causal Organism

Rhizoctonia solani

Damage

• The pathogens cause seed decay, root rot, damping-off, seedling blight, stem canker and leaf blight in green gram.
• The disease occurs commonly at podding stage.
• In the initial stages, the fungus causes seed rot, seedling blight and root rot symptoms.
• The affected leaves turn yellow in colour and brown irregular lesions appear on leaves.
• On coalescence of such lesions, big blotches are formed and the affected leaves start drying prematurely.
• Roots and basal portion of the stem become black in colour and the bark peels off easily.
• The affected plants dry up gradually.
• When the tap root of the affected plant is split open, reddening of internal tissues is visible.

Survival & Favourable Conditions

• The pathogen is soil-borne.

Cultural Control

• Grow resistant varieties.
• Avoid moisture stress in the soil especially at podding stage.

Biological Control

• Seed treatment with 4g Trichoderma viride formulation

Chemical Control

• Seed treatment is effective is reducing the disease incidences.
• Seed treatment with Thiram + Carbendazim (2:1) 0.25% seed reduces the disease.

Rust

Causal Organism

Uromyces phaseoli

Damage

• The disease appears as circular reddish brown pustules which appear more commonly on the underside of the leaves, less abundant on pods and sparingly on stems.
• When leaves are severely infected, both the surfaces are fully covered by rust pustules.
• Shriveling followed by defoliation resulting in yield losses.

Cultural Control

• Use tolerant varieties

Chemical Control

• Spray Mancozeb 3g to control of the disease.

Seed and Seedling Rot

Causal Organism

Rhizoctonia solani, Macrophomina phaseolina
Pythium aphanidermatum, Sclerotium rolfsii

Damage

• Several fungi growing on the seed coat of  green gram cause rotting of the seeds resulting in failure of germination.
• Leaves of affected seedlings dry and die suddenly.
• Basal portion of the stem weakens and appears brown in colour.
• Dried seedlings are seen sparsely here and there in the field within 3 weeks after sowing.

Survival & Favourable Conditions

• The pathogens are soil-borne.

Cultural Control

• Green gram cultivars, PS 16 and Pusa Bisaki are tolerant.
• Seed treatment is advised.

Biological Control

• Seed treatment with 4g Trichoderma viride formulation

Chemical Control

• Seed treatment with 3g Thiram per kilogram of seed can reduce the disease incidence.