What is in this article?:
- Beware of pest problems in wheat following wheat
- Burying stubble slows fly emergence
• Among the problems usually found where wheat follows wheat are the insect pest Hessian fly and diseases problems such as take-all and Fusarium head blight.
Burying stubble slows fly emergence
Burying wheat stubble where Hessian flies over-summer will reduce the emergence of Hessian fly adults.
Burning crop debris also has been recommended for Hessian fly control. However, burning destroys flaxseeds that are present in the straw, but does not kill flaxseeds that have fallen out of the crop debris onto the ground.
Controlling volunteer wheat well before planting is recommended, because Hessian flies are attracted to volunteer wheat when they emerge in September.
Wildlife plantings of wheat, which are often planted early, can be a source of Hessian flies.
Crop rotation helps reduce the chance of infestation by Hessian flies, says Flanders, but it is not infallible, because Hessian fly adults will fly up to a mile in search of host plants.
As far as rotations and diseases are concerned, the main problem with wheat following wheat is take-all disease, says Austin Hagan, Auburn University Extension plant pathologist.
“Historically, take-all has not been as big of an issue in Coastal Plain soils as it has been in the Tennessee Valley region of Alabama. It got to a point to where take-all was so bad growers basically didn’t make any wheat because of it,” says Hagan.
A poor rotation also could lead to fusarium head blight or scab, he says.
“This disease historically has been a problem in the Tennessee Valley where we’ve always had a lot of wheat production. It has been less of an issue in the central and southern parts of Alabama. Corn or sorghum in a rotation can bump up the risk a little more, but we have seen scab outbreaks in wheat behind cotton,” he says.
Losses to fusarium scab blight not only are due to sizable reductions in the germination, numbers, and test weight of seed from scab-blighted heads, but also from the production of mycotoxins by the causal fungus in diseased seed, explains Hagan.
Given favorable weather patterns, wheat drilled behind no-till corn is at highest risk for a destructive scab outbreak, he says.
A variety of control strategies can be employed to prevent scab outbreaks in production fields as well as minimize the risk of contamination of stored wheat and subsequent exposure of livestock to mycotoxins, says Hagan.
“Growers should purchase registered or certified, fungicide-treated wheat seed or apply a hopper box fungicide seed dressing to bin-run wheat seed. Also, avoid sowing wheat directly behind corn or grain sorghum. Growers should plant wheat after a non-host crop of the scab causal fungus such as cotton, peanuts or soybeans.”
The scab risk is higher for no-till compared with conventional-till wheat cropped behind corn or grain sorghum, so plow under or burn stubble and other surface debris associated with either of these crops, he says.
Also, early wheat has an increased risk of scab, says Hagan.
“While considerable advances in the selection of scab-resistant soft winter wheat varieties and breeding lines have been made, none are currently available to Alabama producers. Hopefully, such disease-resistant varieties will be released in the near future.”
Hagan recommends that producers plant rye, oats or a winter legume as a winter cover crop in place of wheat to reduce the risk of scab as well as take-all in subsequent wheat crops.