Alternaria leaf spot of Aloe barbadensis in relation to environmental factors

The quantitative relationship between mean air temperature, relative humidity and cumulative rainfall was studied with development and progress of Alternaria leaf spot (Alternaria alternata (Fr.) Keissler) of Aloe barbadensis. The correlation analysis revealed that mean minimum air temperature, maximum relative humidity, minimum relative humidity and cumulative rainfall were positively correlated during all the years whereas mean maximum air temperature showed negative correlation during 2010 with the disease development and progression. However, the mean minimum temperature and minimum relative humidity were highly positively correlated. The favourable climate for the development and progression of Alternaria leaf spot of A. barbadensis included a mean air temperature between 24 to 32 ^oC, relative humidity between 60 to 90 per cent and higher cumulative rainfall.