2 results
Weed management and crop rotations influence populations of several broadleaf weeds
- Brian S. Manley, Henry P. Wilson, Thomas E. Hines
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- Journal:
- Weed Science / Volume 49 / Issue 1 / February 2001
- Published online by Cambridge University Press:
- 20 January 2017, pp. 106-122
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In studies conducted from 1991 through 1994, researchers investigated the effects of several crop rotations and herbicide programs on crop yield and populations of common lambsquarters, common ragweed, Amaranthus spp., and jimsonweed at two sites. Crop rotations included continuous corn, continuous soybean, corn–soybean, and corn–tomato–soybean, and herbicide programs were the split-plots and included continuous use of acetolactate synthase (ALS)–inhibitor herbicides, continuous use of non–ALS-inhibitor herbicides, annual rotations between ALS- and non–ALS-inhibitor herbicides, combinations of ALS- and non–ALS-inhibitor herbicides in the same year, and no herbicide. Weed control and weed populations generally were affected by an interaction between crop rotations and herbicide programs. After 4 yr, common lambsquarters control was lowest, and populations were highest where fomesafen was used alone for four consecutive years or in rotation with other herbicides. Although common ragweed populations were low at site 2, control at both sites was generally lowest from treatments that included only ALS-inhibitor herbicides. Common ragweed populations were highest at site 1 in 1992 and 1993 following continuous applications of ALS-inhibitor herbicides. Jimsonweed populations were also low at site 2, but control at site 1 in tomato was low. Jimsonweed control from fomesafen and the combination of butylate plus atrazine in soybean and corn, respectively, was variable. Amaranthus spp. populations decreased as the study progressed, and in 1993, control was over 90% from all treatments, except in the case of the treatment combining butylate plus atrazine. Corn and soybean yields varied with year and site, and yields of these crops and tomato were related to rainfall and weed control.
Management programs and crop rotations influence populations of annual grass weeds and yellow nutsedge
- Brian S. Manley, Henry P. Wilson, Thomas E. Hines
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- Journal:
- Weed Science / Volume 50 / Issue 1 / February 2002
- Published online by Cambridge University Press:
- 20 January 2017, pp. 112-119
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The effects of several crop rotations and herbicide programs on populations of goosegrass, stinkgrass, large crabgrass, smooth crabgrass, fall panicum, and yellow nutsedge were investigated at two sites from 1991 to 1994. Crop rotations were continuous corn, continuous soybean, corn–soybean, and corn–tomato–soybean. Herbicide programs were the split-plots and included continuous use of acetolactate synthase (ALS)-inhibitor herbicides, continuous use of non–ALS-inhibitor herbicides, annual rotations between ALS- and non–ALS-inhibitor herbicides, combinations of ALS- and non–ALS-inhibitor herbicides in the same year, and no herbicide. Grass and yellow nutsedge densities generally were affected by an interaction between crop rotations and herbicide programs by 1994. Goosegrass densities in 1994 were highest from the continuous use of ALS-inhibitor herbicides in the corn–tomato–soybean rotation and were generally high in 1994 in the continuous corn and corn–tomato–soybean rotations. Stinkgrass densities were highest by 1994 where imazethapyr was applied alone for four consecutive years. Stinkgrass densities were also high where imazethapyr was applied in combination with butylate for 4 yr and at Site 2 (designated Northampton) where imazaquin plus nicosulfuron was applied for 4 yr. Herbicide programs did not produce shifts in large crabgrass densities, except that densities were highest where butylate plus atrazine was applied for 4 yr. Smooth crabgrass was present in significant densities at Site 1 (designated Accomac) only where imazaquin plus nicosulfuron was used for 4 yr or at Northampton from continuous ALS-inhibitor programs. Fall panicum densities were highest by 1994 where the combination of butylate plus atrazine was applied continuously for 4 yr. Yellow nutsedge control was lowest and densities were highest at Northampton where the combination of fomesafen plus fluazifop-P plus fenoxaprop was applied continuously for 4 yr. Yellow nutsedge densities by 1994 at Northampton were also high where these herbicides were applied with imazaquin for 4 yr or where these herbicides were applied in rotation with imazaquin plus nicosulfuron or butylate plus atrazine.