Abstract

Bioassay studies of several biocides against Pectobacterium carotovorum ssp. carotovorum revealed that ciprofloxacin proved highly inhibitive to bacterial growth by producing highest inhibition zone (21 mm) at a concentration of 200 µg ml^-1 followed by penicillin, tetracycline, and oxytetracycline. Other test chemicals viz., amoxicillin, striplin, azithromycine, mercuric chloride, bleaching powder, sodium hypochlorite and copper-oxychloride, produced a moderate to low inhibition zone. Studies on use of effective antibiotics for post-harvest management of soft rot revealed ciprofloxacin as the most effective by giving a disease control of 84.78, 97.78 and 80.43% when used as pre, simultaneous, and post inoculation sprays respectively, on cabbage heads. Other three antibiotics viz., penicillin, tetracycline and oxytetracycline also gave good control of the disease. Factorial experiment aiming to study the combined effect of biocides and packing materials (polythene bags, net bags, gunny bag, and cardboard boxes) reveals that cabbage heads treated with ciprofloxacin and packed in net bags showed the lowest rot intensity of 4.5%, with lowest weight loss due to maceration after six days of storage, whereas cabbage heads packed in poly bags without any biocide treatment showed the highest rot intensity of 77.78% with the highest weight loss during the same course of time. These tested compounds and packing materials demonstrate the potential for management of post-harvest soft rot caused by P. carotovorum ssp. carotovorum especially for regions lacking cold store facility during post-harvest and transit period.

Key words: Pectobacterium carotovorum ssp. Carotovorum