Correlation of disease with meteorological factors and management of Septoria leaf spot of chrysanthemum (Chrysanthemum grandiflorum)

摘要

Leaf spot severity was high at 25 degrees C and lowest at 35 degrees C temperatures. Relative humidity more than 96% influenced the spread of the disease to maximum by causing 57.20% disease severity. In field, the disease usually appears in June and reached to maximum in August with rise in relative humidity and rainfall in both the years (2003-04). The simple, partial and multiple correlations, indicated a positive correlation of disease concerning rainfall and relative humidity while temperature had a negative effect on disease development. The co-efficient of multiple determinations signifies 66.03 and 67.40% variation with the positive weather factors of disease development. In in vitro studies, 7 fungicides three from each systemic (contaf, roverol and bavistin) and non-systemic (SAAF, dithane M45 and dithane Z78) category arrested the mycelial growth of the pathogen up to 73% generally at higher concentrations. In field contaf, SAAF, roverol were found equally good in controlling the disease, followed by dithane M45, dithane Z78 and benomyl.