Control of Weeds and Volunteer Plants During Winter Wheat Seeding

Control of weeds and volunteer plants during winter wheat seeding is critical in the management of wheat streak mosaic virus (WSMV). WSMV is a viral disease that can seriously affect both spring and winter wheat. Infected wheat plants may die, fail to set seed, be stunted, or be unaffected, depending how early they were infected. Damage can range from reduced yield to crop failure.

The virus is transmitted by the wheat curl mite and leaves rubbing each other. Mites can be spread from field to field by wind. Both mites and virus overwinter on winter wheat and in the spring the mites multiply rapidly and are blown to nearby spring wheat fields or volunteers. These hosts harbour the mites and virus over the summer, which may blow onto nearby winter fields completing the disease cycle.
There are NO pesticides available for control of the mites or virus. The key control method is to disrupt the life cycle of the mite by preventing infection of winter wheat.
Ideally, you should control all volunteer plants and grassy weeds at least two weeks before planting, including those in neighbouring fields. The mites can’t live longer than 10 days in the absence of living plants, therefore without a “green bridge” of one grass to the next you can stop the mites from moving. You need to burn off grassy weeds like green foxtail and barnyard grass in the stubble where you are going to seed winter wheat.
Do not sow winter wheat near immature spring wheat or other cereals and seed only after spring crops are mature. Plant winter wheat as late as possible to avoid the period when the mites are moving off late-maturing cereal crops. In North Dakota severe WSMV injury has been found in winter wheat planted next to late maturing corn fields. Mites move into the green corn as spring cereals mature and then move from the corn onto newly emerged winter wheat seedlings. Avoid planting winter wheat next to green corn if there has been WSMV in the area.
For further information, contact your GO representative.