|Previous||1 of 3||Next|
small (250x250 max)
medium (500x500 max)
large ( > 500x500)
Entomology and Plant Pathology, Oklahoma State University 127 Noble Research Center, Stillwater, OK74078 405.744.5527 Vol. 12, No. 6 http://entoplp.okstate.edu/Pddl/ Mar 21, 2013 Wheat Disease Update Bob Hunger, Extension Wheat Pathologist On Monday & Tuesday of this week, Nathalia Graf Grachet (OSU graduate student) and I worked in plots around Stillwater and toured wheat fields and variety trials/demos located at Banner Road [just west of Oklahoma City (OKC)], Minco (25 miles southwest of OKC), Apache (20 miles north of Lawton), Kingfisher (30 miles northwest of OKC), and Marshall (35 miles west of Stillwater). Wheat along this loop was either approaching or at GS 6 (first node detectable) and ranged from about 6-12 inches in height. We were somewhat surprised at how good much of the wheat looked in this traveled loop, although it was apparent that moisture was needed as the surface was hard, cracking and dry in the top 1-2 inches at most of the stops. Perhaps the moisture forecast over the next 3-4 days will alleviate this. We found no rust (leaf or stripe) at any stop, and only found lightly scattered pustules of powdery mildew at two locations (Banner Road and Apache). Without a doubt, the disease highlight of the trip was two fields and the variety trial at Apache. Both fields were Duster growing in no-till wheat residue with the straw residue being last year’s crop of Duster wheat. The straw was covered with the black “resting bodies” (pseudothecia) of the fungus that contain spores of the fungus that causes tan spot (Fig 1). In late February and March, these resting bodies release spores that infect the lower leaves of wheat plants when there is abundant moisture on the leaf surfaces. This had occurred in both fields and the variety trial that was in one of the fields as the lower leaves of wheat plants were heavily spotted with tan spot lesions (Fig 2). Rainy/wet periods from this point on will promote sporulation in the lesions and spread of tan spot up the canopy. This is an excellent example of where an early application of a fungicide to help stop the spread of tan spot is indicated. Such an early application will not protect from later infection by rusts, but will help to control diseases such as tan spot, septoria, and powdery mildew that survive on wheat residue/straw left on the surface of the soil. In such cases, I strongly recommend considering the application of a fungicide to help control and limit the spread of this early season tan spot to the upper canopy.
|Okla State Agency||
Oklahoma State University
|Okla Agency Code||
|Title||Pest e-alerts, 03/21/2013, v.12 no.6|
Oklahoma State University. Cooperative Extension Service.
|Purpose||Wheat Disease Update, Bob Hunger;|
|For all issues click||
|Digital Format||PDF, Adobe Reader required|
|ODL electronic copy||Downloaded from agency website: http://entoplp.okstate.edu/pddl/2013/PA12-6.pdf|
|Rights and Permissions||This Oklahoma state government publication is provided for educational purposes under U.S. copyright law. Other usage requires permission of copyright holders.|