Now is a good time to plan for controlling volunteer wheat, said Jim Shroyer, K-State Research and Extension agronomy state leader.
"Recent problems with wheat streak mosaic, High Plains Virus, and triticum mosaic virus in much of western and parts of central Kansas remind us of the importance of controlling volunteer wheat well before this year´s crop is planted," he said.
Volunteer wheat within a half-mile of a field that will be planted to wheat should be completely dead at least two weeks before wheat planting, Shroyer said. This will help control wheat curl mites, Hessian fly, greenbugs, Russian aphids, and other insect pests in the fall.
One of the most important threats from volunteer wheat is the wheat streak mosaic virus complex, which includes the High Plains Virus and the newly discovered triticum mosaic virus, said Jeff Whitworth, K-State Research and Extension entomologist.
"In most cases, an infection of wheat streak mosaic can be traced to a nearby field of volunteer wheat, although there are other hosts, such as corn, millet, and many annual grasses, such as yellow foxtail and prairie cupgrass. Control of volunteer is the main defense against the wheat streak mosaic virus complex," he explained.
"The wheat curl mite is the vector for both wheat streak mosaic, the High Plains virus, and triticum mosaic virus. The curl mite uses the wind to carry it to new hosts and can travel up to half a mile from volunteer wheat," Whitworth explained.
Volunteer wheat can also increase problems with Hessian fly, he added.
"Hessian flies survive over the summer on wheat stubble. When the adults emerge, they can infest any volunteer wheat that may be present, which will keep the Hessian fly population alive and going through the upcoming crop season. In years with a wet summer and/or a long open fall, there can be two broods of Hessian fly in the fall; and this is even more likely where volunteer is allowed to grow and become infested early," the entomologist said.
In addition, volunteer wheat is a host of greenbugs and bird-cherry oat aphids which are the vectors for barley yellow dwarf, Whitworth said. Russian wheat aphids may also live over the summer on volunteer wheat.
"While this insect has wings and can be windborne for hundreds of miles, the vast majority of fall infestations in Kansas appear to originate from nearby infested volunteer," he said.
A number of other insects are also associated with the presence of volunteer wheat, Whitworth said. An example in western Kansas is the Banks grass mitea.
"During some years, infestations become established during late summer and early fall on volunteer wheat. Later, as the quality of the volunteer deteriorates, mites move from the volunteer into adjacent fields of planted wheat or other small grains. Occasionally mites will survive the winter and continue to spread into the planted wheat following greenup in the spring," he said.
A concern in eastern Kansas is the chinch bug. Occasionally, adult bugs will fly from maturing sorghum fields in late summer to nearby fields where volunteer wheat is growing.
"Where infested volunteer is allowed to grow right up until seedbed preparation just prior to planting, early planted continuous wheat is likely to become infested. Similarly, volunteer that is allowed to grow through the fall and into the following spring may also serve as an attractive chinch bug host," Whitworth said.
Of course, much depends on the uniformity of the remaining stand and the weather for the rest of the growing season," he added.
More information is available in the K-State publication MF-1004, "Be A Good Neighbor: Control Your Volunteer Wheat."