In most cases, there is no question that volunteer wheat should be controlled so that it is dead two weeks before planting wheat. That is to reduce problems with wheat curl mites (and wheat streak mosaic), Hessian fly, bird cherry oat aphids (and barley yellow dwarf), among other problems.
What if the volunteer emerges at the same time the planted wheat emerges? Volunteer that does not emerge until the time planted wheat emerges, or even later, does not need to be controlled. But if the volunteer emerges shortly before wheat is planted, it’s probably still a good idea to control it two weeks before planting since this volunteer will still provide a green bridge for mite and insect pests.
Controlling volunteer with a herbicide such as glyphosate can present a challenge if it is done close to the time of wheat planting since it takes some time for the volunteer wheat to completely die. As the volunteer dies, any wheat curl mites that are on the plants will leave and could end up on planted wheat. Gramoxone may be a better option than glyphosate for control of small, late-emerged volunteer wheat close to wheat planting time because it provides a much quicker control than glyphosate. Gramoxone generally is not as effective as glyphosate for complete control of volunteer wheat, especially if it is larger and tillering, but can provide good control of smaller wheat.
It would be best not to have any planted wheat within a half-mile of this volunteer wheat until it has been dead for two weeks. This should give enough time for the wheat curl mites to die naturally. At this point in the season, that will cause wheat planting to be pushed toward the end of the recommended range of planting dates, as well as the cutoff for crop insurance purposes in most areas.
Nevertheless, where volunteer is present before wheat planting, landowners and producers should do themselves and all their neighbors a favor, and control the volunteer two weeks before the wheat is planted.
For more information, see K-State publication MF-1004, Be a Good Neighbor: Control Your Volunteer, at your local county Extension office or on the web at: www.ksre.ksu.edu/library/crpsl2/Mf1004.pdf.