Temperature and Alternative Hosts Influence Aceria tosichella Infestation and Wheat Streak Mosaic Virus Infection.

Wheat streak mosaic, caused by Wheat streak mosaic virus (WSMV; family Potyviriclae), is the most important and common viral disease of wheat (Triticum aestivum L.) in the Great Plains of North America. WSMV is transmitted by the wheat curl mite (WCM; Aceria tosichella). We evaluated how mean daily temperatures, cumulative growing degree-days, day of the year, and sumounding alternative host identity affected WCM infestation and WSMV infection of wheat from late summer through early autumn in Montana, United States. Cumulative growing degree-days, warm mean daily temperatures (i.e.. >10°C), and sumounding alternative hosts interacted to alter risk of WCM infestation and WSMV infection. Wheat sumounded by Bromus tectorum L. and preharvest volunteer wheat had WCM infestation and WSMV infection rates of 88% in years when the mean daily temperature was 15°C in October, compared with 23% when sumounded by bare ground, and <1% when the temperature was 0°C regardless of sumounding alternative host. Mean daily temperatures in the cereal-growing regions of Montana during autumn are marginally conducive to WCM population growth and movement. As the region continues to warm, the period of WCM movement will become longer, potentially increasing the frequency of WSMV outbreaks. [ABSTRACT FROM AUTHOR]