Assessment of disease severity at different planting dates and evaluation of fungicides for the management of cowpea rust disease

Abstract

Cowpea rust caused by Uromyces phaseoli var. vignae (Barclay) Arthur is one of the major production constraints in India. An experiment was laid out to assess the effect of different planting dates and fungicide treatments on the disease severity. The study was conducted during Kharif 2016-17. C-152, a susceptible cowpea variety was evaluated at 12 different sowing dates starting from July 18th of 2017 to November 5th of 2017. The observations were recorded at weekly intervals. The crop sown on 17.07.2020 recorded minimum disease severity of 4.65% at 77 days after sowing and maximum a of 45.2% at 105 DAS on 5.11.2017, indicating that a lower disease severity at first date of sowing than the later sowings. The analysis between disease severity and weather parameters revealed that maximum temperature, relative humidity and wind speed to be positively correlated and that minimum temperature and relative humidity morning to be negatively correlated with the disease severity. In another experiment six fungicides with two different concentrations were evaluated against the disease under field conditions. Among them propiconazole 25% EC at 0.2% was very effective in reducing the rust severity significantly compared to other fungicides. It also recorded highest average yield of 13q/ha.