Bacterial Wilt or Brown Rot (Pseudomonas solanacearum):

Brown rot or bacterial wilt is a destructive disease of the potato. It causes losses in two ways: (i) premature wilting and death of the plants leading to total loss of yield, and (ii) rotting of the tubers in transit or storage. The earliest symptom is slight wilting of the top, which is soon followed, by total wilting. In advanced stage, if the base of the stem of the affected plants is cut transversely and squeezed, the bacterial mass is seen to ooze out as a dull white slimy mass on the cut surface.

Two types of symptoms are produced in tubers, viz. vascular rot and pitted lesions. In vascular rot, the vascular tissues look like a water soaked circle, which subsequently may turn brown. The lesions on tuber are produced due to infection through lenticels (skin pores). Initially water soaked spots develop which enlarge forming pitted lesions.

Control:

The infected seed tubers including apparently healthy seed tubers from diseased crop are important in spread and carry over of the disease. Hence, disease free seed tubers obtained from disease free areas should be used for planting. Splitting of the tubers at the time of the planting should be avoided as splitting spreads the disease even to health tubers. Application of stable bleaching powder (12kg/ha) mixed with fertilizer in furrows while planting reduces wilt incidence by 80%. Practicing crop rotation for 2-3 years with crops like maize, finger millet, cereals, garlic, lupin, and onion cabbage can reduce the disease inoculum.