Epidemiology of Alternaria in sunflower.

Alternaria leaf blight disease was favored by high rainfall, high relative humidity, (85-93%),More rainy days (5 days /wk),Low sunshine hours (1.5 h/day),High wind speed and temperature of 23-270C. Disease severity was more in 31st July, 16th August sown crop than other dates of sowing. Disease was significantly positively correlated with rainfall and with relative humidity (maximum and minimum), Spore load, dew period and low sunshine hours. Spore load was more in August month