Impact of climate on Spot Blotch (Bipolaris sorokiniana) severity on wheat (Triticum aestivum) crop over Eastern Gangetic Plains (EGP) of India

Spot blotch (SB) in wheat crop is caused by Bipolaris sorokiniana, become an epidemic in warm and humid regions. The climate influences the incidence and severity of the crop diseases. The present study is an attempt to assess the role of climatic parameters on the SB of wheat. The experiment was conducted on susceptible wheat varieties grown under timely and late sown conditions at Varanasi for three consecutive years (2014-15, 2015-16, and 2016-17). The Multi Liner Regression (MLR) model revealed that the R2 for disease severity was 0.74 and 0.72, for timely and late sown conditions, respectively. Autoregressive Integrated Moving Average (ARIMA) models were evaluated to predict the SB severity. Out of eight ARIMA models, ARIMA (1, 0, 1) was the best fit to predict the disease severity. The R2 and RMSE were 0.88 and 7.61, respectively for the timely sown condition. For the late sown, R2 was 0.86 and RMSE 5.48. It was noted that the disease incidence and severity increased rapidly during 8th to 13th SMW that follows after the heading. The risk of SB increased after heading in those areas characterized by average maximum temperature >30 °C with high relative humidity >50%. The outbreaks of SB were recorded during this period. This study will help wheat growers of the EGP for timely adaptation of management practices and breeder for the screening of SB resistant germplasms.