Cause A fungus, Erysiphe trifoliorum (formerly E. polygoni), which overwinters on the plant and on diseased crop residue. It seldom seriously reduces seed production, but it can reduce forage yield and quality. The disease is common on red clover and occasionally on white and alsike clovers.
Symptoms Leaf surfaces are covered with pale gray, powdery fungus growth. Severely infected leaves yellow and die.
Cultural control Plant recommended cultivars.
- Badge SC (Group M1) at 0.5 to 1.8 pints/A on 7- to 14-day intervals. Preharvest interval is 0 days. 48-hr reentry.
- Quadris Flowable (Group 11) at 6 to 15.5 fl oz/A. Use of an adjuvant is recommended. Do not apply within 14 days of harvest for forage and hay. 4-hr reentry.