Entomology and Plant Pathology, Oklahoma State University
127 Noble Research Center, Stillwater, OK74078
Vol. 11, No. 17
Apr 9, 2012
Wheat Disease Update
Bob Hunger, Extension Wheat Pathologist
Thursday and Friday (Apr 05-06) I visited variety trials/demos or fields at Kingfisher (50 miles west and 20 miles south of Stillwater), Minco (40 miles south of Kingfisher), Apache (25 miles north of Lawton), Lawton, Snyder (35 miles west of Lawton), multiple fields east and west of Frederick/Manitou area (20 miles south of Snyder), Altus, Granite (30 miles north of Altus), and multiple fields located 20 miles north of Clinton. Wheat was mostly in the heading to flowering range with the exception of the fields north of Clinton, which were in the boot to just heading range (mostly later planted). Below are observations by disease.
Leaf rust was at a very low incidence along the entire route with only widely scattered pustules observed.
Barley yellow dwarf spots were seen occasionally at nearly every stop, but BYD was not as widespread or severe as I have seen it in trials here at Stillwater.
Powdery mildew was not found at any stop – I just realized that I really wasn’t looking for PM, but if it had been heavy I can’t imagine I would have missed it.
Stripe rust could be found at nearly every location as widely scattered short stripes. I found one large (5 ft X 10 ft) “hot spot” at Kingfisher, but didn’t find any at Minco and very little north of Clinton. In most cases where stripe rust was found, sporulation also was found. However, in southwestern OK, it was apparent that in many of the stripes the pustules had “deactivated” or “shut off” due to the hot temperatures two weeks ago, but were starting to activate (sporulate) again since the start of the wet and cool weather this past week. At no location did I see heavy, widespread stripe rust. Mark Gregory (Southwest OK Area Extension Agronomist) visited most