In general, complete control of all plants present at the time of planting is required for successful weed control. With direct drilling (no-till), vegetation control is accomplished before planting with burndown herbicides such as paraquat (Gramoxone) or glyphosate. Other herbicides such as Sharpen may be tank-mixed with these products to help improve control of certain weed species (e.g., glyphosate-resistant horseweed). The required application rate varies, depending on weed species and size. Refer to the product labels for details. Gramoxone provides faster kill. Glyphosate is preferred if perennial weeds are present, but fields with serious perennial weed problems should not be direct drilled with a small grain until the perennial weeds have been controlled.
The need for a burndown herbicide depends on the species of weeds present. If no weeds are present, a burndown herbicide is not needed. For fall-seeded small grains, fields with small seedlings of species that DO NOT overwinter (summer annuals only) and are present at low densities DO NOT need a burndown herbicide. If the weeds are large, however, or capable of overwintering (winter annuals, biennials or perennials) or if identification of the weeds cannot be confirmed, a burndown herbicide should be used. For spring-seeded small grains, a burndown herbicide should be used if any weeds are present at planting time, regardless of species or size.
Herbicides applied after small grain emergence are not affected by the tillage system used. All of the herbicides listed below can be used in all tillage systems including direct drilling. No weed problems are unique to no-till small grain production. Therefore, no-till small grain production does not present any special weed control concerns.
For more information on weed control in wheat, please visit the MSU Weeds site or the resources below: