Integrated disease management in Blackgram

MS Jeberson, KS Shashidhar, B Sinha *

Cercospora Leaf Spot

Cercospora Leaf Spot (CLS) is caused by several species and may cause severe yield losses under humid weather conditions. Leaf spots with brown to greyish centre and reddish brown border are its characteristic symptoms. The petioles, stems and pods also get affected by the pathogen. The fungus survives on the infected seeds and crop debris.

Powdery Mildew

Powdery mildew is a major problem for urdbean cultivation and causes severe yield loss. This disease is caused Erysiphaepolygonii. The disease appears on all the part of plants above soil surface. Disease initiates as faint dark spots, which develop into small white powdery spots, coalescing to form white powdery coating on leaves, stems and pods and later turns dirty white.

The disease induces forced maturity of the infected plant causing heavy yield losses and its intensity increases in stress condition. It is favoured by cooler conditions and is wide spread in the late planted crop.

Anthracnose

The disease occurs on several legume crops including urdbean. This disease is caused by the Colletotrichum spp. Affecting aerial plant parts, however, the leaves and pods and more vulnerable. The characteristic symptoms of this disease are circular brown sunken spots with dark centers and bright red orange margins on leaves and pods.

Infection just after germination causes seedling blight. The pathogen survives from one crop season to the next on infected seeds and crop residue. The optimum temperature and relative humidity for disease development are 17-240C and 100%, respectively.

Cultural Control

o Field sanitation, crop rotation and destruction of infected crop debris.
o Adopt clean cultivation by destroying diseased plant refuge
o Delayed sowing of urdbean with wider spacing’s considerably reduces the disease severity

Mechanical Control

o Hot water seed treatment at 580C for 15 minutes has been found effective in checking the seed-borne infection and increasing proportion of seed germination

Biological Control

o Seed treatment and soil application of Trichoderma spp./Pseudomonas fluorescence enriched FYM at the time sowing of crop

Use of Plant Extract/Organic Molecules

o For powdery mildew spray with Neem Seed Kernal Extract @ 50 g/l or neem oil 3000 ppm @ 20ml/1 twice at 10 days interval from initial disease appearance.
o Spray with eucalyptus leaf extract 10% at initiation of the disease and 10 days later also if necessary

Chemical Control

o For Cercospora, treat the needs with thiram/Captan @ 2.5g/kg of seed. On appearance of the symptoms spray with Carbendazim 50 WP @ 1.0 g/1 or Mancozeb 45 WP @ 2.0 g/l. Subsequent spray should be done after 10 to 15 days, if required. Spraying with Copper Oxychloride @ 3 to 4 g/1 water ahs also been found effective in management of this disease.
o For powdery mildew spray with water soluble Sulphur 80 wp @ 4 kg/1
o For anthracnose, seed treatment with thiram 80% WP @ 2 g/l or Captan 75 WP @ 2.5 g/l helps in eliminating the seed borne infection. Spray the crop with 0.2% zineb 80% WP @ 2 g/l or Ziram 80% WP @ 2 g/l with first appearance of symptoms on the crop and repeat after 15 days (if necessary)


For further details contact:-
Public Relations & Media Management Cell,
CAU, Imphal.
Email: [email protected]