MANAGEMENT OF POST HARVEST GREY AND WHITE MOLD DISEASES OF FRENCH BEAN (Phaseolus vulgaris L.) BY EMPLOYING BIOCONTROL AGENTS AND ELICITORS
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Date
2019-08
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University of Horticultural Sciences, Bagalkot
Abstract
An experiment entitled “Management of post harvest grey and white mold diseases of french bean (Phaseolus vulgaris L.) by employing biocontrol agents and elicitors” was conducted in the Department of Post Harvest Technology, College of Horticulture, Bagalkot, Karnataka during the year 2018-2019. In the present experiment, efforts were made to screen and identify safer, non-chemical and efficient methods to manage grey and white mold post harvest diseases of french bean.
In the present experiment, five isolates of Botrytis cinerea and four isolates of Sclerotinia sclerotiorum were isolated from infected french beans. Among those, B. cinerea isolate-4 and S. sclerotiorum isolate-3 exhibited highest per cent disease index (PDI) with 72.22% and 66.67% and highest virulence index with 5.06 and 4.67 respectively. Under in vitro study, identified 3 fungal and 6 bacterial antagonists are found to be capable of inhibiting the growth of B. cinerea and S. sclerotiorum. The studies from the dual-culture technique showed that the bacterial isolates, BBIS-8, BBIS-6 and BBIS-7 can inhibit mycelial growth of B. cinerea and S. sclerotiorum to the extent of more than 75% (against B. cinerea-77.72%, 77.71% & 76.98% and against S. sclerotiorum-78.54%, 78.53% & 77.80% respectively).
The results of in vivo screening of elicitors showed that post harvest treatment with chitosan-0.5% (T2) and salicylic acid-200 ppm (T7) for 5 minutes to be the most effective with least disease incidence of grey mold (T2-35.19 and T7-37.04 PDI) and white mold (T2-18.52 and T7-22.22 PDI) with more shelf life (5 days).
Based on the effect of individual treatment of elicitors, biocontrol agents and physical treatments on physico chemical parameters and sensory properties of B. cinerea and S. sclerotiorum inoculated french beans, three best treatments viz., chitosan-0.5% (T5), ozonation-0.0235 ppm (T3) and Trichoderma harzianum-108 cfu/ml (T7) were evaluated in combinations. Among the combination treatments, T8 (ozonation + chitosan-0.5% + Trichoderma harzianum) showed the lowest PDI with 16.67% & 24.07% and more shelf life (5 days) in B. cinerea and S. sclerotiorum challenge inoculated french beans respectively and this study was confirmed that combination of treatments were more effective than the individual treatments to manage grey and white mold post harvest diseases of french beans.
The two best treatment combinations from the previous experiments were also tested for their ability to enhance shelf life of normal (without any pathogen inoculation) french beans. The lowest PDI (22.67%), PLW (7.51%), highest shelf life (8.6 days) and significantly higher sensory scores for color and appearance (7.10), texture (6.59) and overall acceptability (6.95) were recorded in T3 (ozonation + chitosan-0.5% + Trichoderma harzianum) at 8 days after storage.