Pulses :: Blackgram

 

1. Anthracnose-Colletotrichum lindemuthianum
2. Bacterial Leaf Blight- Xanthomonas phaseoli
3. Cercospora leaf spot-Cercospora canescens
4. Powdery Mildew-Erysiphe polygoni
5. Root Rot and Leaf Blight- Rhizoctonia solani
6. Rust-Uromyces phaseoli
7. Stem canker-Macrophomina phaseolina
8. Yellow Mosaic – Mungbean Yellow Mosaic Virus
9. Leaf Crinkle-Leaf Crinkle Virus

1. Anthracnose: Colletotrichum lindemuthianum

Symptoms 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.
  2. Bacterial Leaf Blight- Xanthomonas phaseoli
  

  Symptoms 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. The bacterium is seed-borne Rain splashes play an important role in the development and spreading of the disease.

  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.

  3. Cercospora leaf spot-Cercospora canescens

  Symptoms 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

  • Intercrop 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.
                                                                                                     

  4. Powdery Mildew-Erysiphe polygoni

  Symptoms 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.

  5. Root Rot and Leaf Blight-Rhizoctonia solani

  Symptoms 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

  6. Rust: Uromyces phaseoli

  Symptoms 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.

  Management

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

  7. Stem canker-Macrophomina phaseolina

  Symptoms 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.

  8. Yellow Mosaic – Mungbean Yellow Mosaic Virus

  Symptoms

  • 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.

  9. Leaf Crinkle-Leaf Crinkle Virus

  Symptoms 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.