July 2, 2009
Stripe rust was found in commercial fields of spring wheat in the Dayton area and the Palouse region. Although rust incidences were generally low (1-5%), rust pustules were very actively producing spores. Growth stages range from before boot to after flowering. As the weather conditions have been and will be favorable (the highest temperatures are mostly in 80s and lowest temperatures in 40s and 50s, and dew forms in many fields) for rust infection and development in the next two weeks, stripe rust is expected to increase on spring wheat crops. If you grow susceptible cultivars of spring wheat, please check your fields and consider fungicide application if you see about 2-5% incidence or severity. The fields we saw with stripe rust are grown with Hank or Nick having very susceptible reaction. Spring wheat cultivars Hank, Nick, WPB 926, Lolo, Tara 2002, Jefferson, and IDO377s used to be highly resistant, but have become susceptible in the recent years. In addition, Scarlet, Eden, Macon, and Zak are susceptible. When you see stripe rust in fields of these cultivars, it is better to spray. Cultivars Louise, Alpowa, Otis, and Wakanz have HTAP resistance. You may see some necrotic stripes in fields of these cultivars, they are not necessary to spray.
As the growth stage of spring wheat crops varies so much, please check the labels of fungicides to see which one can be used for your crop.