Wheat disease updates are written by Dr. Bob Hunger, Extension Plant Pathologist

I and Nathalia Grachet (OSU Graduate Student) returned Friday from a trip and field days in the panhandle of Oklahoma.  Wheat at Lahoma (25 miles west of Enid) ranged from full berry (watery) to the milk stage.  Driving further to the northwest after about Alva was depressing as the condition of the wheat and the landscape in general deteriorated with what seemed like each passing mile.  The field days we attended were at Balko (40 miles east of Guymon) and Hooker (20 miles northeast of Guymon).  Wheat in these trials ranged from flowering to full berry (watery).  Rick Kochenower (Panhandle Area Specialist – Agronomy) related the story that demonstrates the resilience of wheat.  The Balko area was hit hard by the last freeze in April such that he felt there would be no wheat there.  However, a mild May with just a little moisture allowed secondary tillers to come back, and if some rainfall and mild temperatures occurs for the next couple of weeks, some wheat will be harvested in the area.  This is not the scenario over the entire panhandle.  According to Rick, wheat in Cimarron County (far western county in the panhandle) is all but gone primarily due to drought whereas in Texas and Beaver County freeze and drought have both played a role in severely impacting wheat production.

Leaf and stripe rust were found this past week around Stillwater but not at a typical incidence or severity; leaf rust is especially lacking.  Dr. Art Klatt reported being able to easily find leaf rust in his plots near Perkins, OK (15 miles south of Stillwater) in the range of 5-20S, which is lighter than typical.  At Lahoma, Nathalia and I found both leaf and stripe rust but at low incidence and severity (especially leaf rust).  Leaf spotting was more common, but it was difficult to determine if this was Septoria, Stagonospora, tan spot and/or physiological.

Signs of wheat streak mosaic and barley yellow dwarf can still be observed, especially around Lahoma where flag leaves are still mostly green.  In the panhandle and northwestern OK it is difficult to discern virus damage from freeze and drought.

Reports/excerpts of reports from other states:

Nebraska – Dr. Stephen Wegulo (Small Grains Extension Pathologist, Univ of Nebraska, Lincoln, NE) 24-May-2013:  Wheat in Nebraska is mostly in the boot to heading growth stages.  There have been no new reports or observations of rust diseases since the observation of stripe rust at Mead on May 7.  On May 21 and 22, I surveyed wheat fields in Lancaster, Saline, and Saunders Counties in southeast Nebraska.  I did not find any rust diseases.  The stripe rust that was observed at Mead on May 7 stopped activity following the high temperatures we had during the week of May 13 (including 100+ deg F on May 14), and never spread, similar to Carl Bradley’s observation in Champaign County, IL.