Two field experiments were conducted by using cheap and ecofriendly plant products and biocontrol agents for the management of powdery mildew disease caused by <italic>Erysiphe polygoni</italic> in black gram which is causing severe yield loss. The mean per cent disease incidence ranged from 15.80 to 47.70 in different treatments. The maximum reduction of disease incidence was recorded in wettable sulphur 0.25% (15.80%) followed by carbendazim 0.1% (58.91%) and castor oil 1% with

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... yces quisqualis</italic> (48.53 %) However castor oil 1% followed by <italic>A. quisqualis</italic> application at 10 days interval recorded 20.28 per cent increased yield with maximum cost benefit ratio of 1 : 2.01