Effect of weather parameters on the development of die-back of pear caused by Botryodiplodia theobromae

The effect of some weather parameters viz., temperature, relative humidity, rainfall and number of rainy days on the development of die-back on three cultivars of pear was studied by correlation and regression analysis during 2005 and 2006. The per cent disease index (PDI) on all varieties exhibited negative correlation with average maximum temperature during 2005 and 2006, whereas, it showed a positive correlation with average minimum temperature, maximum and minimum relative humidity, total rainfall and number of rainy days during both the years under field conditions. The PDI was highly correlated with mean maximum relative humidity followed by mean minimum relative humidity on Baggugosha and Punjab Beauty and on Patharnakh during 2005 and 2006, respectively. Maximum infection rate was observed in the month of June-July during 2005 and 2006 on Baggugosha. Area under disease progress (AUDPC) was also maximum on Baggugosha during both 2005 and 2006 years.