This article was written by Dr. Bob Hunger, Extension Wheat Pathologist

Department of Entomology & Plant Pathology

Oklahoma State University – 127 Noble Research Center

405-744-9958 – bob.hunger@okstate.edu

This past week and today, I traveled and looked at wheat in central OK near Kingfisher (35 miles northwest of OKC) and near El Reno (20 miles west of OKC) as well in north-central/northwestern OK near Lahoma (15 miles west of Enid), Alva and Cherokee.  Wheat was mostly in the soft to medium dough stage, but only about full kernel to milk in northern OK (Alva and Cherokee).  In central OK, flag leaves were mostly gone, primarily due to rust (both stripe and leaf, but mostly leaf).  In the more northern areas (Lahoma, Alva, and Cherokee), there was still green flag leaves on varieties with resistance to leaf/stripe rust.

Samples testing positive for Wheat streak mosaic virus, High plains virus, and Barley yellow dwarf virus continue to come to the Diagnostic Lab, with samples now coming more from northwestern OK and the panhandle.  For more information on mite-transmitted wheat viruses such as WSM, please see OSU Fact Sheet EPP-7328 (Wheat Streak Mosaic, High Plains Disease, and Triticum Mosaic: Three Virus Diseases of Wheat in Oklahoma) available at http://wheat.okstate.edu/wheat-management/insectsdisease/EPP-7328.

Reports/excerpts of reports from other states:

Dr. Erick DeWolf, Wheat Extension Pathologist, Kansas State University, May 12, 2017:  “Stripe rust and leaf rust were rapidly increasing in incidence and severity in parts of central Kansas this week. Stripe rust and leaf rust became established in the upper canopy of wheat in south central Kansas a few weeks ago. Observations this week indicate that stripe rust has increased in severity in many fields of susceptible varieties that were unprotected by fungicides. In some cases, more than 30 percent of the flag leaf area has been damaged by the disease. Leaf rust has also moved to the upper leaves on susceptible varieties in the south central region.

Stripe rust and leaf rust were also reported in additional areas of the state this week with many new reports of the disease in middle canopy in west central and northwest regions of the state. There are a few reports of stripe rust moving to the upper leaves in these areas also, but for the moment this seems to be rare.”