Incidence of bacterial soft rot of carrot in Meghalaya and ecofriendly postharvest management
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Date
2019
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College of Post Graduate Studies in Agricultural Sciences, Central Agricultural University, Imphal
Abstract
Carrot (Daucus carota L.) is one of the most important widely grown root vegetables. Carrots contain vitamin A, antioxidants, and other nutrients. The productivity and quality of the carrot in the field as well as in storage is affected by many fungal and bacterial diseases. Among those, bacterial soft rot caused by Pectobacterium caratovora subsp caratovora is a major postharvest disease. The market surveys carried out to study the incidence and severity of postharvest bacterial soft rot in carrot during July-September and November-February, 2018-19 at 30 days intervals in two districts of Meghalaya. Total four markets were selected from each district i.e., Ri-Bhoi (Byrnihot, Nongpoh, Bhoirymbong and Umroi) and East Khasi Hills (Bara Bazaar, Jhalupara, Laitumukrha and Polo). The wide range of variation was observed in both incidence (0.0-50%) and severity (0.0-17.17%) of disease. Among the markets, the highest incidence (50%) was recorded in Nongpoh (Ri-Bhoi district) in the month of August, where as it was lowest (4.57%) in Byrnihot (East Khasi Hills district) in February month. Similarly, the highest severity (17.17%) was also recorded in Nongpoh (Ri-Bhoi district), in the month of July and lowest (3.47%) in Jhalupara (East Khasi Hills district) in February month. The pathogen was identified as gram –ve bacteria based on morphological and biochemical characteristics. The host range of the pathogen was also studied by inoculating in 8 different hosts (tomato, chilli, cabbage, ginger, potato, radish onion and pineapple). Among the tested hosts, radish was found to be most susceptible to the bacterial soft rot pathogen showing 22.67% of soft rot intensity and ginger was found to be resistant with no symptom of on rhizomes. In-vitro evaluation of botanicals showed that garlic (10%) was the most effective botanical with 10.8mm inhibition zone, followed by neem (8.83mm) at 10%. Among the different timings of inoculation, simultaneously with the inoculation and application of 10% garlic extract showed less severity (24%), followed by 12 hrs prior to inoculation (41.5%). Among the tested postharvest salts sodium hypochlorite (5%) was recorded for maximum zone of inhibition (12.17mm) followed by ammonium bicarbonate (11.7mm ) at 3%. Evaluation of four packaging material against bacterial soft rot pathogen, net bag was the most effective which showed less severity (8.51%), followed by gunny bag (10.52%). Among the integration of treatments sodium hypochlorite +net bag was showed less severity (6.80%), followed by garlic+net bag (7.7%). The present study has revealed that bacterial soft rot is a major postharvest problem of carrot in two districts of Meghalaya. Garlic, Sodium hypochlorite and Net bag in different combination and integration could be the promising treatments against bacterial soft rot of carrot.