Entomology and Plant Pathology, Oklahoma State University
127 Noble Research Center, Stillwater, OK74078
Vol. 12, No. 16
May 20, 2013
Wheat Disease Update
Bob Hunger, Extension Wheat Pathologist
Wheat in southern/southwestern Oklahoma is maturing and will speed up with the warmer (>90 F) over the last couple of days. In central Oklahoma, around Stillwater and to the north, wheat is just finishing or has just past flowering and kernel development is starting. As you head to northwest Oklahoma, wheat also is in late flowering or has just finished flowering. I’m not sure about out toward the panhandle but know there is not much wheat that will be harvested as you move west of Woodward and Buffalo. I’ll be taking a trip to the panhandle the end of the coming week and will report more after that trip.
Disease-wise, not a lot changed over the past week in Oklahoma. Leaf rust remained practically absent although infections in the 15-40S range were observed in Jagalene (or Jagger) guard rows in breeder plots at Stillwater. However, little to no leaf rust was found elsewhere around Stillwater and no reports were observed or reported from north-central and northwestern Oklahoma. Stripe rust is slight more prevalent. Several “hot spots” were noted around trials at Stillwater and occasional “stripes” (but not hot spots) were noted at field days west of Enid, north of Ponca City, and north of Stillwater. Leaf spotting diseases, barley yellow dwarf, and wheat streak mosaic (WSM) are the most commonly observed diseases in samples seen at field days and submitted to the Plant Disease and Insect Diagnostic Clinic. This past week a few samples also tested positive for High plains virus. Several reports from Ag Educators, consultants, and growers have indicated that WSM has devastated wheat in fields in northern and western Oklahoma. In all cases where I talked to the person, there was an indication that volunteer wheat was involved either in the field or adjacent to it.