ARS | Publication request: Effect of temperature on latent period of Stagonospora nodorum blotch in winter wheat

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: May 27, 2010
Publication Date: June 1, 2010
Citation: Zearfoss, A., Cowger, C., Ojiambo, P.S. 2010. Effect of temperature on latent period of Stagonospora nodorum blotch in winter wheat. Phytopathology.

Technical Abstract: Stagonospora nodorum blotch (SNB) is caused by Stagonospora nodorum (teleomorph = Phaeosphaeria nodorum) and yield losses from severe disease epidemics can be as high as 50%. To establish a model for SNB development based on the effects of temperature on pathogen latent period relative to the host, batches of two winter wheat cultivars (AGS 2000 and USG 3209) were inoculated with pycnidiospores of S. nodorum at weekly intervals from February 2009 to June 2009. After an incubation period of 72 h, plants were exposed to field conditions where temperatures ranged from -6.6°C to 35.8°C with a mean batch temperature of 9.7°C to 23.7°C. Latent period expressed as the time from inoculation until the first visible symptoms, ranged from 8 to 34 days. A shifted cumulative gamma distribution model with a base temperature of 0.5°C best described the relationship between number of lesions with pycnidia and accumulated thermal time. When defined as time to 50% of the maximal lesions with pycnidia, latent period was estimated as 297 and 313 degree-days above the base temperature of 0.5°C for USG 3209 and AGS 2000, respectively. The relationship between the inverse of latent period, defined as time to 50% maximal lesions with pycnidia, and the mean batch temperature was best described using a linear model (r2 = 0.93, P < 0.001). This study provides data that link wheat growth with SNB progress and will facilitate the construction of disease development models for use in timing of fungicide application.