|Southern Division - Effects of infection timing on Wheat streak severity|
J. A. PRICE (1), J. Gray (2), F. Workneh (2), C. M. Rush (2). (1) Texas A&M AgriLife Research, Amarillo, TX, U.S.A.; (2) Texas A&M AgriLife Research, Bushland, TX, U.S.A.
<i>Wheat streak mosaic virus</i>, vectored by the wheat curl mite (<i>Aceria tosichella Keifer</i>), causes severe reductions to grain production and water use efficiency and is one of the most economically important wheat viruses found throughout the Great Plains region of the United States. Dual purpose wheat, for grazing and grain production, is typically planted late August to early September when average temperatures are warm, increasing the likelihood of early virus infection. Delaying planting until cooler temperatures usually results in reduced disease incidence and severity, possibly due to environmental conditions not optimal for both vector and virus. Little is known about the impact of early and late spring infections on disease severity, yield, and water use efficiency. Therefore, studies were conducted to evaluate the effects of early, middle, and late spring virus infections, at three different irrigation levels. Significant increases in disease severity, soil moisture, and decreased grain yield were found for fall inoculated plots. Later season inoculations were found to have increased grain yield, water use efficiency and decreased severity. However, uniform reductions in disease severity were not found during the early and mid-spring treatments, which were influenced by cooler temperatures at the time of inoculation. This information can be used to design precision management strategies during Wheat streak infection and for modeling disease loss estimates.