|
|
|
|
 |
|
 |
 |
 |
 |
 |
 |
 |
|
|
 How Combinations of Cultural Practices Aid Weed Control March 1999 USDA research in south central North Dakota and northeastern Colorado underscores the synergism for sunflower weed control that occurs when two or more helpful cultural practices are combined. While the main reason(s) for employing practices such as narrow rows, higher plant populations, delayed planting and cover cropping may not necessarily relate directly to weed control, such practices can provide an important assist in that regard, report Don Tanaka and Randy Anderson. Tanaka is a soil scientist with the USDA-ARS Northern Great Plains Research Laboratory at Mandan, N.D., while Anderson is director of the Central Great Plains Research Station at Akron, Colo. Since 1995, they've coordinated research into methods and technologies for the development of high-residue production systems for dryland sunflower in the Northern and High Plains. Along with that objective, the USDA scientists have looked at how various cultural practices may likewise aid with weed control. "Use of cultural practices to improve weed control reduces producer input costs, potential for herbicide-resistant weeds, and pesticide contamination of surface and ground waters," they point out. What have Tanaka and Anderson concluded? Based on their 1998 research with weed control in no-till sunflower, and prior work conducted at both Mandan and Akron during 1995-97, they note, not surprisingly, that there's no "one size fits all" formula for cultural weed control across the entire Great Plains. "Because of variations in climate and precipitation patterns, cultural practices for effective weed control in sunflower need to be developed by regions," they emphasize. As to specific cultural practices, they conclude the following: o Crop Canopy - Narrow rows (i.e., 15 to 18 inches apart) and higher plant populations (i.e., 25 percent or more above normal populations) help suppress weeds and also tend to increase subsequent seed yield - regardless of location. That's due to the enhanced competitiveness of the sunflower canopy when there are more plants in a given field and those plants are closer together. Tanaka notes that narrow rows in the Northern Plains commonly have resulted in yield increases of from 10 to 30 percent versus standard 30-inch rows; and, combined with higher populations, also improve weed control. o Delayed Planting - A delayed planting date can have a large impact on weed control in the High Plains, but it's likely to have a limited or no effect in the Northern Plains. The difference lies in the length of the growing season - and planting window - in the respective regions. "Because of the longer growing season, [this is] one of the most effective practices to minimize weed growth" in the High Plains, say the USDA researchers. o Nitrogen Placement - Tanaka and Anderson say banding nitrogen near the planted row contributes to reduced weed growth in the Northern Plains growing region. That's because a broadcast application naturally will "feed" between-row weeds as well as the sunflower. In the High Plains, however, banding has a minimal effect on weed growth reduction because the soils themselves are releasing quite high levels of nitrogen during the warm June planting/early growth phase. o Rye Cover Crop - Irrigated growers in the High Plains have been able to make a rye cover crop work in their sunflower; but dryland producers generally won't fare as well, suggest Tanaka and Anderson. That's because "water is more limiting and rye can become a weed if winter wheat is grown in the rotation" - which is usually the case in the High Plains. For Northern Plains producers, a rye cover crop can effectively reduce weed growth; but it also can contribute to moisture stress in the sunflower crop, they add. o Hybrid Choice - "Differences in growth habits of sunflower hybrids [are] not sufficient to aid weed control" in the High Plains, the USDA scientists state. In the Northern Plains, any effect one's choice of hybrids may have on weed control is overshadowed by the need to choose hybrids based on other essential considerations, such as yield and oil content potential and disease tolerance.  Back to Minimum Till/No-Till Stories Back to Archive Categories
|
|
