Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/25/2005
Publication Date: 1/31/2006
Citation: Donald, W.W. 2006. Preemergence banded herbicides followed by only one between-row mowing controls weeds in corn. Weed Technology. 29(1):143-149.
Interpretive Summary: To control weeds in field corn, alternative methods are needed that reduce herbicide contamination of surface or ground water. If herbicides are banded over corn rows, between-row mowing close to the soil surface can substitute for herbicides to cut herbicide use about 50%. This is enough to decrease water contamination by herbicides, such as atrazine. The goals of this research were to determine how often and when to mow to best control common annual weeds in field corn and maximize corn yield. In one two-year-long study, giant foxtail and common waterhemp were well controlled in field corn by a weed management system consisting of herbicide (atrazine + metolachlor) banded over crop rows before crop emergence and one late between-row mowing well after weeds had grown tall enough to be mowed. In a second three-year-long study, similar weed infestations were well controlled by postemergence herbicide (atrazine + nicosulfuron + crop oil concentrate) banded over crop rows after crop emergence and between-row mowing early, twice, before the corn canopy closed over. This research demonstrates that farmers may have more flexibility in timing weed control with between-row mowing than with field cultivation or herbicide treatment. These research results should interest farmers, farm equipment manufacturers, weed scientists, government action agencies, and environmental lobby groups. However, practical use of this research must await commercial development of suitable between-row mowers for row crops.
Technical Abstract: Research was conducted to determine the minimum number of between-row mowings necessary to control annual weeds, chiefly giant foxtail and common waterhemp, without corn yield loss. Over 2 yr in Missouri, the between-row mowing systems that were evaluated consisted of a 38-cm band of PRE atrazine plus metolachlor at 2.2 plus 2.2 kg ai/ha applied over corn grown in 76-cm rows shortly after planting followed by one, two, or three between-row mowings close to the soil surface. Based on rated total weed control, between-row total weed cover, and corn yield, the weed-free check was statistically indistinguishable from a treatment in which banded PRE herbicide was followed by only one between-row mowing, late, when weeds were relatively large. When mowed once at 52 to 64 DAP, giant foxtail and common waterhemp were greater than 85 cm tall. The yield was not increased by mowing earlier or more than once.