EFFICACY OF SOME CHEMICALS IN CONTROLLING CITRUS CANKER DISEASE

Abstract

Citrus canker caused by Xanthomonas axonopodis pv. citri is one of the most devastating disease hampering worldwide citrus production. A Laboratory and a pot experiments was conducted to evaluate the efficacy of some chemicals in controlling citrus canker disease under the Department of Plant Pathology, Sher-e- Bangla Agricultural University, Dhaka during the period from July, 2015 to September, 2016. Xanthomonas axonopodis pv. citri was purified by restreaking on nutrient agar medium and confirmation was done by pathogenicity test. The bacterium was gram negative, rod shaped with rounded ends. It showed negative result in oxidase test and positive result in KOH solubility test, starch hydrolysis test, catalase test, citrate utilization test, gelatine liquefaction test. On NA medium the bacterium appeared as circular, mucoid, convex, yellow to orange colour and on SX medium the bacterium produced yellow to slightly blue, mostly circular, small, flattened, mucoid colonies. In-vitro evaluation of chemicals indicated that 0.2% Dithane M 45 (Mancozeb) at 96 hours of incubation showed highest (31.91%) inhibition zone against Xanthomonas axonopodis pv. citri among the four tested chemicals. Cl solution, Sulcox 50 WP and Companion showed moderate result against the bacterium. In pot experiment, among the seven different chemicals, Mancozeb (Dithane M 45) was found highly effective against Xanthomonas axonopodis pv. citri. The highest disease incidence and severity were found in control treatment and the lowest incidence and severity were found in Dithane M-45 treated plants.