Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/16/2006
Publication Date: 4/1/2007
Citation: Donald, W.W. 2007. Between-row mowing systems control summer annual weeds in n0-till grain sorghum. Weed Technology 21:(2)511-517. Interpretive Summary: Throughout the Mid-west, persistent herbicides, such as atrazine, can wash off fields in runoff water during storms. Then, this herbicide-laden runoff can contaminate surface and ground water. To minimize the chance of water contamination by herbicides, farmers need effective alternative ways to manage weeds in field crops, such as corn and grain sorghum (milo), that reduce herbicide use. One way to halve total herbicide use is to reduce the area of fields treated with herbicides by substituting unconventional mechanical weed control for herbicides between rows. In published research in soybean and corn, preemergence herbicide use was reduced 50% by banding herbicides over crop rows and substituting between-row mowing for cultivation. The objectives of this research were (1) to determine whether such between-row mowing systems adequately controlled weeds and prevented grain yield loss in other competitive field crops, such as no-till grain sorghum, and (2) to compare broadcast herbicide treatments with between-row mowing systems. Just after planting no-till sorghum, atrazine and dimethenamid (i.e., Aatrex and Frontier) were banded over rows at full and reduced registered rates. When weeds growing between rows became tall enough to mow, they were trimmed close to the soil surface. Such between-row mowing systems successfully controlled weeds, prevented weeds from reducing yields, and can be used in grain sorghum. The between-row mowing systems also were as effective as conventional broadcast herbicides in grain sorghum based on measured weed cover and grain sorghum yield. These applied results should interest farmers, extension agents, mower manufacturers, herbicide manufacturers, weed scientists, and environmentalists who wish to minimize herbicide contamination of surface water.
Technical Abstract: In previous research, use of preemergence soil residual herbicides was reduced 50% in no-till corn and soybeans by banding herbicides over crop rows followed by mowing weeds growing between rows two times. The research goals were (1) to determine whether such between-row mowing systems adequately controlled weeds and prevented grain yield loss in other competitive field crops, such as no-till grain sorghum, and (2) to compare broadcast herbicide treatments with between-row mowing systems. Preemergence atrazine plus dimethenamid at relative rates of 0.75X and 1X (where 1X = 1.7 plus 1.3 kg ai/ha, respectively) were band-applied over rows shortly after planting followed by two between-row mowings close to the soil surface. In 2 of 3 yrs in Missouri, this system controlled giant foxtail and common waterhemp as well as broadcast herbicides in no-till sorghum. In 2 of 3 yrs, between-row mowing systems also prevented yield loss in no-till sorghum as well as both broadcast herbicides at the same rates and the weed-free check.