Developmental Behaviour of Leaf Blight of Taro Caused by Phytophthora colocasiae

Phytophthora leaf blight is a major fungal disease of taro (Colocasia esculenta var. antiquorum) which infects the leaves, petioles and corms. The experiment was conducted to study the effect of different weather parameters viz., temperature, average relative humidity, cumulative rainfall and sunshine on the developmental behavior of Phytophthora leaf blight. The correlation studies indicated that maximum temperature, average relative humidity, cumulative rainfall and sunshine hours were positive but significantly correlated in all the genotypes in Kharif 2006 & 2007 respectively. However, the minimum temperature had a negative correlation with respect to disease development in all taro genotypes. The highest value of regression coefficient (97%) was recorded on genotype NDC-50, while the lowest regression coefficient was observed in genotype NDC-1 (80%) in both the years. The present investigation revealed that frequent rainfall, maximum temperature in the range of (21–32°C), high relative humidity (100%) and bright sunshine hours had a positive correlation on the development of disease in taro.