Control of bacterial wilt of potatoes by agronomic practices¹

Agronomic practices like use of seed potato from disease free area, blind earthing, stable bleaching powder application @ 12 kg/ha in soil at planting, early planting and early harvesting and control of weeds by paraquat and summer/winter ploughing were tested for their efficacy in controlling bacterial wilt and brown rot of potato caused by Pseudomonas solanacearum at seven locations representing six agroclimatic zones of India. At Deesa and Chhindwara seed contributed 100% primary inoculum and the disease was controlled completely by use of disease free seed.

At Shillong, Bhowali, Ranchi, Kalyani and Bhubaneshwar 50–75% of primary inoculum came through seed tubers produced in wilt infested areas and 25–50% from other sauces like native vegetation. Wilt and brown rot incidence was reduced by 50–100% (70–100% at most places) and 50–85% by disease free seed + bleaching powder application mixed with fertilizer at planting+blind earthing. Ploughing the land after harvest of potato crop and exposing the soil to winter temperatures in hills and summer temperatures in plains reduced wilt and brown rot by 50–83% and 50–70% at Ranchi, Shillong and Bhowali, by 78–100% and by 50–82% at Kalyani. Early planting by third week of June in hills reduced bacterial wilt by 71–83% and brown rot by 71–86%. The above treatments increased emergence as well as yield and have been recommended for control of the disease.