Studies on bacterial leaf spot disease of tobacco.

Abstract A new bacterial disease of tobacco, not previously reported was found in Karnataka. Studies on the disease initiated to identify the causal agent the factors which predispose the plants to epidemics, and control of the disease, revealed that it occurs in epiphytotic form following heavy rains after the crop has been topped, and is more severe in thicker leaves. The primary source of inoculum is the soil, and secondary spread takes place by rainwater splashing from infected to healthy plants. The disease is found predominantly in beedi tobacco and causes severe damage to the crop resulting in economic loss in yield. The causal organism is Erwinia chrysanthemi. In vitro evaluation of chemicals showed that streptomycin sulphate + chlorotetra‐cycline (Streptocycline), streptomycin sulphate (Ambystrin) and streptomycin sulphate + oxytetracycline (Paushamycin) were effective in control of the bacterial disease.