Vol. 11, Special Issue 8 (2022)

Author(s):
CS Choudhary, RS Singh, A Arun, V Bharati, Md. Minnatullah and RK Choudhary

Abstract:
Amongst the fungal diseases of oilseed Brassica crops, Sclerotinia rot incited by Sclerotinia sclerotiorum (Lib.) de Bary, which was earlier considered to be a minor problem in India has now became a serious problem of rapeseed-mustard growing areas of country including Bihar. This disease is becoming major constraints to cultivation of this oilseed Brassica crops in present conditions. Infection of pathogen occurs on the leaves, stems and pods at different developmental stages of plant causing losses in seed yield of up to 80% as well as significant reductions in oil content and quality also. Management of Sclerotinia rot with chemical fungicides though remains successful, accumulation of pesticide residues in the edible parts threatens its quality for consumers, as well as the scope for export of the commodities to other countries. Most of the conventional methods are not effective in management of the disease. Hence, to meet the challenge, the integration of various IPM measure may be the best approach. Connecting with this, a field trial on effect of different dates of sowing on disease development had been carried out during Rabi 2016-17 and 2017-18. The crop sown on November 30^th, recorded lowest per cent Sclerotinia rot disease incidence. A relatively higher disease incidence (37.42% & 40.12% respectively and 38.78% on pooled basis) was recorded in the crop sown on November 10^th, and corresponding lower incidence was observed with delayed or earlier dates of sowing during both the years of experimentations and on pooled basis also. Highest seed yield of 1290 kg/ha & 1260 kg/ha respectively and 1275 kg/ha on pooled basis was recorded when crop was timely sown on 30^th October during both the years. Highest seed yield was not recorded with early and late sown crop (October, 20^th and November, 30^th respectively), despite comparatively less disease incidence. This might be attributed to crop phenology and meteorological parameters (Envⁿ.) during these sowing dates. Multiple Regression Equation between per cent disease incidence and weather variables i.e. R²=0.6554, 0.6751 & 0.6653 In pooled indicated that the combined effect of these weather variables favoured the disease development causing upto 65 to 67 per cent variation in the Sclerotinia rot incidence.