, Farm Journal Seeds & Production Editor
Some simply call it scab. Others call it head blight or pink mold. Whatever you call it, wheat scab is rearing its ugly head this season.
University of Illinois plant pathologist Carl Bradley has been touring wheat fields and has yet to come across one in Illinois that doesn't have some level of the disease. Fusarium wheat scab is easily recognized at this time of year because in spikelets or the entire wheat heads appear prematurely ripened or bleached. Where the rachis is infected, all portions of the head above that point will be affected. The disease can move down the head and infect the upper part of the stem too. Fungal mycelium and pink or orange spore masses may be seen on or at the base of the infected spikelets.
The disease is generally most serious under wet or humid weather conditions and wet has been the word in many areas of the Midwest. Bradley says infected spikelets are often sterile or contain shriveled and/or discolored kernels. When disease pressure is high, fields can experience significant yield losses of up to 50% or more.
"Your best defense if you have head scab is to increase the air flow on your combine during harvest to eliminate as much of this light weight scab-infected grain as possible,” says Bradley. Scabby grain can present major problems in marketing and storage. It's also problematic for feeding because it can contain a toxin that is particularly harmful to non-ruminants. While ruminant animals are more tolerant, the toxin apparently can remain stable in grain for several years and the FDA has established guidelines of 2 ppm in grain prior to milling, 1 ppm for finished flour products and 4 ppm for animal feed.
Watch our video as Bradley describes Fusarium wheat scab:
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