EFFECT OF ENVIRONMENTAL FACTORS ON Phytophthora BLIGHT DEVELOPMENT OF COLOCASIA

Progress of Phytophthora blight of taro (Colocasia esculenta var. antiquorum) caused by Phytophthora colocasiae Racib. was found greatly influenced by environmental factors prevalent under field condition. Per cent plant infection, disease intensity, coefficient of disease index and related progress of disease were periodically recorded on a susceptible variety Narendra Arvi-2. The maximum and minimum infection rate ('r') was observed in 33rd and 32nd standard week during 2006 and 2007. Disease intensity and per cent plant infection were significantly but positively correlated with rainfall and relative humidity in both the year. Disease intensity and per cent plant infection were negatively but none significantly correlated with maximum temperature in 2007 but positively correlated in the year 2006. However, rest of the weather factors were positively correlated to disease intensity and per cent plant infection in both the years. Relative humidity, cumulative rainfall and sunshine hour were found most congenial environmental factors for leaf blight development of taro.