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Agricultural crops :: Pulses :: Blackgram

Blackgram Diseases

Anthracnose - Colletotrichum lindemuthianum

Bacterial Leaf Blight - Xanthomonas phaseoli

Cercospora leaf spot - Cercospora canescens

Powdery Mildew-Erysiphe polygoni

Root Rot and Leaf Blight - Rhizoctonia solani


Rust - Uromyces phaseoli

Stem canker - Macrophomina phaseolina

Yellow Mosaic - Mungbean Yellow Mosaic Virus

Leaf Crinkle - Leaf Crinkle Virus

Anthracnose: Colletotrichum lindemuthianum

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

Management
  • Seed treatment with Carbendazim 2g/kg
  • Remove and destruct plant debris
  • Spray Mancozeb 2g/lit or Carbendazim 0.5g/lit.



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 Bacterial Leaf Blight- Xanthomonas phaseoli

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



Management
  • Use disease free seed
  • Destruction of debris and stubbles.
  • Soak the seeds 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.



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 Cercospora leaf spot-Cercospora canescens

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



Management
  • ntercrop with tall growing cereals and millets.
  • Follow clean cultivation.
  • Use disease free seed.
  • Maintain low crop population density and wide row planting.
  • Mulching reduces the disease incidence resulting in increase yield.
  • Spray with Carbendazim 0.5g/lit or Mancozeb 2.0g/lit at 30 days after sowing.



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Powdery Mildew-Erysiphe polygoni

Symptom
  • 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.
  • 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.


Management
  • The seeds must be sown early in the month of June to avoid early incidence of the disease on the crop.
  • Powdery mildew could be controlled by spraying Carbendazim 1g/lit or Tridemorph 1 ml /lit.




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Root Rot and Leaf Blight-Rhizoctonia solani

Symptom
  • 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. The pathogen is soil-borne.


Management
  • Seed treatment with 4g Trichoderma viride formulation



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Rust: Uromyces phaseoli

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



Management
  • Spray Mancozeb 2.5g/lit to control of the disease.



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Stem canker-Macrophomina phaseolina

Symptom
  • In rice fallows, symptoms appear on 4 weeks old black 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 dark green, mottled and reduced in size.
  • Normal leaves on the affected plants drop suddenly and dry.
  • Flowering and podding is greatly reduced.



Management
  • Deep ploughing in summer.
  • Follow crop rotation
  • Soil amendment with farm yard manure @ 12.5 tonnes/ha is helpful in reducing the incidence of the disease
  • Destroy the diseased plant debris by burning of burying in the soil.
  • Seed treatment with T. viride @4g/kg or P. fluorescens @ 10g/ kg of seed or Carbendazim or Thiram 2g/kg of seed.
  • Spot drenching with Carbendazim 1g/lit or P. fluorescens / T. viride 2.5 kg/ha with 50 kg FYM.



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Yellow Mosaic – Mungbean Yellow Mosaic Virus

Symptom
  • The disease is more prevalent on black gram than green gram
  • Initially mild scattered yellow spots appear on young leaves.
  • The next trifoliate leaves emerging from the growing apex show irregular yellow and green patches alternating with each other.
  • 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.

Management
  • Grow resistant/ tolerant varieties viz.,Vamban 4, Vamban 5
  • Grow seven rows of sorghum as border crop
  • Treat seeds with Imidacloprid 70 WS @ 5ml/kg to control vector.
  • Rogue out MYMV infected plants early in the season to eliminate the source of inoculum.
  • Give one foliar spray of systemic insecticide (Dimethoate @ 750 ml/ha) on 30 days after sowing



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Leaf Crinkle-Leaf Crinkle Virus

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

Management
  • Periodical removal of infected plants upto 45 days.
  • Spray Acephate 1g/lit or Dimethoate 2 ml/lit to control vector.

 


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