Abstract
The effects of temperature on Wheat yellow mosaic virus (WYMV) propagation and symptom development in wheat plants were investigated under both field and growth chamber conditions. Throughout the 5-year investigation using a WYMV-infested field, disease incidences varied, but disease progression patterns were similar among the years of investigation. Disease incidences and severities increased when the daily mean air temperature (DMAT) was approximately 5°C, and decreased by masking when the DMAT was above 10°C. Under growth chamber conditions, when wheat plants were mechanically inoculated with WYMV and grown under controlled environmental conditions at 5, 10 and 15°C, the latent periods for symptom development and virus detection were shorter at 10°C than at 5°C. The symptoms rapidly disappeared at 10°C, while they appeared gradually at 5°C, but were more severe than those at 10°C. No symptoms appeared at 15°C. These results show that air temperature differentially affects WYMV development and expression: the optimal temperature for symptom development is approximately 5°C, while the optimal temperature for virus propagation is approximately 10°C.
