DISTRIBUTION OF RESISTANCE TO COPPER, ZINC AND STREPTOMYCIN IN XANTHOMONAS-CAMPESTRIS PV VESICATORIA (DOIDGE) DYE IN INDIA AND ITS IMPACT ON CONTROL OF BACTERIAL SPOT OF TOMATO

Isolates of Xanthomonas campestris pv. vesicatoria, causal organism of Bacterial Spot of tomato, showed a widespread presence of resistance to copper and zinc. Isolates differed in their levels of resistance to these bactericides. Few isolates with high resistance to copper and zinc also showed resistance to streptomycin. An effort to control Bacterial Spot on tomato incited by isolates with differing levels of resistance showed copper oxychloride in combination with mancozeb, mancozeb alone or streptomycin sulphate to be effective in controlling X c. pv. vesicatoria isolates with lower levels of resistance. Isolates with higher levels of resistance could not be controlled with any of the chemicals or their combinations used in the studies. A study on persistence of resistance to bactericides on storage in vitro revealed that lower levels of resistance were maintained over a long time, however the higher levels declined and stabilized at the lowest level of resistance in the absence of bactericides.