Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: June 30, 2005
Publication Date: July 25, 2005
Citation: Olanya, O.M., Larkin, R.P. 2005. Effects of temperature and relative humidity on development of Late Blight incited by phytophthora Infestans isolates from diverse genotypes and hosts. American Phytopathological Society Abstracts. July 2005; v. 95. p. S77. Technical Abstract: Isolates of Phytophthora infestans of diverse genotypes derived from potato, tomato and hairy nightshade hosts have been reported in Maine; however, the effects of pathogen genotype, origin host, environmental condition, and their interactions on late blight disease development are not fully known. The effects of temperature, relative humidity (RH) and wetness duration on late blight incited by isolates from various genotypes and hosts were assessed on potato plants in growth chambers. Combinations of different genotypes were also evaluated for late blight development. Variation in late blight severity was observed, and highest disease was detected on the 100/111/122 genotype. Mean infection frequency on potato leaves ranged from 2 to 67%. The optimum temperature for late blight progression was 22 C and was similar among all genotypes. Disease levels increased with RH greater than or equal to 90%. Source of inoculum had limited impact on late blight disease development. Different genotypes of P. infestans were similarly affected by temperature, relative humidity and wetness duration. These results suggest that pathogen genotype, temperature and relative humidity can significantly affect disease development and epidemiological components.