Epidemiology of alternaria leaf blight of cluster bean caused by Alternaria cucumerina var. cyamopsidis

Abstract

Alternariasps are economically important pathogens widely distributed throughout the world and cause devastating disease on field crops. Alternaria leaf blight is a common disease in guar-growing area of western India and Pakistan. Severe Alternaria blight of cluster bean was also reported from Pusa and Madras. The Alternaria blight of Cluster bean was negatively correlated with maximum and minimum average temperature, whereas significant and positive correlation was observed with maximum and minimum average relative humidity and total rainfall. The regression equation also indicates the the Alternaria blight disease was negatively correlated with the maximum tempratature and positively influenced by average relative humidy and total rainfall. In epidemiological studies, it was concluded that meteorological parameters viz; maximum and minimum average temperature showed negatively correlation with the disease incidence. While maximum and minimum average relative humidity and total rainfall were positively and significantly correlated with the disease intensity. Temperature and relative humidity play a crucial role apart from the other parameters in the development of the disease. Alternaria blight is favoured by low temperature, high humidity and rainfall.