Correlation of Weather Variables on Emergence of a Virus Disease Bud Necrosis Disease of Greengram Incited by Soybean Yellow Mottle Mosaic Virus at Raichur, Karnataka

Abstract

Greengram [(Vigna radiata (L.) Wilczek] is the important pulse crop after chickpea and pigeonpea cultivated in India which is called as “Queen of pulses”, the crop is proned to be infected by many fungal and bacterial diseases. In recent years emergence of a virus disease bud necrosis of greengram was noticed in Raichur and the incidence of disease gradually increased in greengram growing areas of Karnataka. Incidence of bud necrosis disease of greengram and correlation with weather factors was studied during Kharif 2021 at research plot and MARS, UAS, Raichur, Karnataka. The study reveals that, on all four dates of sowing (25th June, 1st July, 9th July and 23rd July 2021), disease was initiated at 25 DAS and highest disease incidence was observed at 75 DAS. The peak activity of thrips was noticed during August month. The weather variables viz., maximum temperature was more than 32 °C, minimum temperature was more than 22°C, rainfall was less than 19 mm/day, morning relative humidity was less than 91 per cent, evening relative humidity more than 44 per cent, evaporation 4.3 mm/day and sunshine hours less than 6 hr/day was favorable for bud necrosis disease in four dates of sowing. Whereas, morning relative humidity, evening relative humidity and age of the crops were having positive relationship with progress of bud necrosis on all four dates of sowing. Thrips and rainfall showed  a positive correlation with disease incidence in all dates of sowing except the fourth date of sowing.