Submitted to: Northeast Potato Technology Forum Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: March 10, 2007
Publication Date: March 15, 2007
Citation: Olanya, O.M., Plant, A.B., Larkin, R.P., Honeycutt, C.W. 2007. Temperature, Relative Humidity and Pathogen Factors Influencing Phytophthora Infestans Development on Hairy Nightshade. Northeast Potato Technology Forum Abstracts. Pg. 48 Technical Abstract: Hairy nightshade (Solanum sarrachoides Sendt) is a common weed that can serve as an alternate host for potato late blight. Although environmental and pathogen factors are key variables affecting the development of late blight, little is known regarding their potential effects on infection of hairy nightshade. The comparative effects of temperature (14, 18, 22, 26 C) and relative humidity (72, 82, 87, 95%) on incubation and latent periods, and late blight development on hairy nightshade were assessed in replicated experiments in growth chambers using P. infestans isolates of diverse genotypes. Incubation period was affected by pathogen isolate and temperature, with symptoms observed after 3-5 days at 22 C, but significant differences at 14 and 26C. Lesion expansion rates also varied among pathogen isolates and temperatures. Late blight developed on hairy nightshade at all temperatures, but no sporangia were detected on intact hairy nightshade plants and disease levels were significantly lower (P <.05) at 14 and 26 C (1-12%) regardless of the pathogen isolate or genotype. Late blight developed on hairy nightshade at all relative humidity (RH) levels, but RH effects varied depending on the pathogen isolate or incubation temperature. Although the epidemic components and disease development were lower on hairy nightshade compared to potato, hairy nightshade may be an important factor in potato late blight development since temperature, relative humidity and pathogen factors impacted late blight development on hairy nightshade.