Weed Control with Reduced Rates of Chlorimuron Plus Metribuzin and Imazethapyr in No-Till Narrow-Row Soybean (Glycine max)

1998 ◽  
Vol 12 (1) ◽  
pp. 32-36 ◽  
Author(s):  
William G. Johnson ◽  
Jeffrey S. Dilbeck ◽  
Michael S. Defelice ◽  
J. Andrew Kendig

Field studies were conducted at three locations in 1993 and 1994 to evaluate weed control and crop response to combinations of glyphosate, metolachlor, 0.5 X and 1 X label rates of chlorimuron plus metribuzin applied prior to planting (PP), and 0.5 X and 1 X label rates of imazethapyr applied early postemergence (EPOST) or postemergence (POST) in no-till narrow-row soybean production. Giant foxtail densities were reduced with sequential PP followed by (fb) EPOST or POST treatments. Large crabgrass was reduced equivalently with all herbicide combinations involving chlorimuron plus metribuzin PP fb imazethapyr. Common cocklebur control was variable but was usually greater with treatments that included imazethapyr. Ivyleaf morningglory densities were not reduced with any herbicide combinations. Sequential PP fb EPOST or POST treatments tended to provide slightly better weed suppression than PP-only treatments, but the difference was rarely significant. Soybean yields with treatments utilizing 0.5 X rates were usually equal to 1 X rates.

Weed Science ◽  
1998 ◽  
Vol 46 (1) ◽  
pp. 105-110 ◽  
Author(s):  
William G. Johnson ◽  
Jeffrey S. Dilbeck ◽  
Michael S. DeFelice ◽  
J. Andrew Kendig

Field studies were conducted at three locations in 1993 and 1994 to evaluate weed control and crop response to metolachlor plus combinations of 0.5 × and 1 × label rates of imazaquin applied preplant and imazethapyr applied early postemergence or postemergence in no-till narrow-row soybean production. Giant foxtail, common ragweed, common cocklebur, and large crabgrass population reductions were greater with sequential preplant metolachlor plus imazaquin followed by early postemergence or postemergence imazethapyr than with preplant metolachlor plus imazaquin or early postemergence/postemergence imazethapyr alone. Ivyleaf morningglory was not effectively controlled by any herbicide program. Pennsylvania smartweed populations were reduced with all herbicide treatments. Soybean yields with treatments utilizing 0.5 × rates were usually equal to 1 × rates if imazethapyr was applied early postemergence or postemergence. Net income with reduced herbicide rates was equal to full-label rates and provided no greater risk to net income.


1997 ◽  
Vol 11 (3) ◽  
pp. 453-459 ◽  
Author(s):  
William G. Johnson ◽  
J. Andrew Kendig ◽  
Raymond E. Massey ◽  
Michael S. Defelice ◽  
Chad D. Becker

Field studies were conducted at three sites in 1993 and 1994 to evaluate weed control, crop response, and economic returns to 0.5× and 1× postemergence rates of chlorimuron, chlorimuron plus quizalofop, bentazon plus acifluorfen, fluazifop plus fenoxaprop, imazethapyr, and imazethapyr plus clethodim in no-till narrow-row soybean production. Common lambsquarters, ivyleaf morningglory, and common ragweed were controlled equally with 0.5× rates applied early postemergence and 1× rates applied mid-postemergence. Control of giant foxtail, large crabgrass, and common cocklebur was generally greater with 1× rates mid-postemergence than with 0.5× rates early postemergence. Soybean yields were equivalent with 0.5× and 1× rates. Soybean yields and net income were highest with 1× and 0.5× rates of chlorimuron plus quizalofop and imazethapyr plus clethodim, and metolachlor preemergence (PRE) followed by 0.5× bentazon plus acifluorfen.


1991 ◽  
Vol 5 (4) ◽  
pp. 845-851 ◽  
Author(s):  
William E. Lueschen ◽  
Thomas R. Hoverstad

Lack of consistent weed control has been a major limiting factor in the adoption of no-till soybean production. Field studies were conducted at Waseca, MN from 1987 through 1990 to evaluate the efficacy of imazethapyr applied either alone or in combination with other herbicides for weed control in no-till soybean. Fall applications of imazethapyr did not provide acceptable weed control. Imazethapyr applied 2 to 4 wk before planting provided a weed-free seedbed whereas burndown treatments applied 1 to 3 d before planting failed to do so. Early preplant imazethapyr applied during the second week of April did not control weeds as well as imazethapyr applied during the last week of April. Imazethapyr applied alone PRE failed to control weeds adequately. A split application of early preplant plus PRE imazethapyr resulted in excellent weed control, especially when metribuzin was added with each application. Imazethapyr is a promising herbicide for weed control in no-till soybean production.


Weed Science ◽  
1981 ◽  
Vol 29 (5) ◽  
pp. 610-615 ◽  
Author(s):  
T. R. Murphy ◽  
B. J. Gossett

Field studies were conducted at Florence and Clemson, South Carolina to measure the influence of soybean [Glycine max(L.) Merr.] planting dates on the length of early-season weed control needed to prevent yield reductions, the rate of shade development, and suppression of annual weeds by soybeans. The rate of shade development was similar for both planting dates during the 9- to 11-week period after planting for Florence and Clemson, respectively. The period of weed-free maintenance required to prevent soybean yield reductions was not affected by planting dates. With cultivation between rows, early- and late-planted soybeans required 3 weeks of weed-free maintenance to achieve maximum yields. Lower weed weights resulted from late than early soybean plantings. At Clemson, 3 weeks of weed-free maintenance for early and late plantings reduced weed weights 97 and 91%, respectively. Weed weights at Florence were reduced 85% with 3 weeks of weed-free maintenance for the late plantings, whereas 5 weeks were required to reduce weed weights 88% for early plantings.


Weed Science ◽  
1989 ◽  
Vol 37 (2) ◽  
pp. 233-238 ◽  
Author(s):  
J. Anthony Mills ◽  
William W. Witt

Field experiments were conducted to evaluate the interactions of tillage systems with imazaquin and imazethapyr on weed control and soybean injury and yield. Control of jimsonweed, common cocklebur, ivyleaf morningglory, velvetleaf, and giant foxtail from imazaquin and imazethapyr in conventional tillage was generally equal to or greater than control in no-tillage. However, under limited rainfall, weed control in no-tillage was generally equal to or greater than control in conventional tillage. Reductions in soybean heights due to herbicide treatment were evident in both tillage systems in 1985 and 1986 but not in. Soybean yields were reduced in 1985 from imazaquin at 140, 210, and 250 g/ha and imazethapyr at 105 and 140 g/ha. Yields were not reduced in 1986 and. Imazaquin and imazethapyr appear to provide adequate control of jimsonweed, common cocklebur, ivyleaf morningglory, velvetleaf, and giant foxtail in conventional and no-till systems.


Weed Science ◽  
1984 ◽  
Vol 32 (3) ◽  
pp. 293-298 ◽  
Author(s):  
R. N. Stougaard ◽  
George Kapusta ◽  
Gordon Roskamp

Several field studies were conducted during 1981 and 1982 to determine whether early preplant (EPP) applications of residual herbicides would prevent the establishment of vegetation before planting no-till soybeans [Glycine max(L.) Merr. ‘Williams’]. Early preplant applications of either cyanazine {2-[[4-chloro-6-(ethylamino)-s-triazin-2-yl] amino]-2-methylpropionitrile} or cyanazine plus oryzalin (3,5-dinitro-N4,N4-dipropylsulfanilamide) were applied in the fall and 3, 2, and 1 month(s) before planting no-till soybeans. In all studies, the treatments prevented vegetation from becoming established before planting, and season-long weed control was achieved with several different treatments. Early preplant cyanazine plus oryzalin provided greater than 90% control for the entire season where grass densities were low. Where grass densities were high (greater than 90% ground cover), EPP cyanazine plus a preemergence application of metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] plus metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one] or a postemergence application of sethoxydim {2-[1-(ethoxyimino) butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} controlled 90% of the weeds, which was equal to or better than the standard preemergence treatments used (80 to 98% weed control).


1992 ◽  
Vol 6 (1) ◽  
pp. 119-124 ◽  
Author(s):  
Larry G. Heatherly ◽  
C. Dennis Elmore ◽  
Richard A. Wesley

Field studies were conducted for three consecutive years to determine if PRE and/or POST herbicides were needed in addition to preplant foliar-applied glyphosate and POST cultivation for maximum seed yield of irrigated and nonirrigated soybean planted in stale and undisturbed seedbeds on clay soil. Soybean seed yields following the use of PRE and POST herbicides alone or in combination were similar in all years, and exceeded seed yield following the use of glyphosate plus POST cultivation only. Plantings made in no-till and fall-till seedbeds produced similar seed yields when both PRE and POST herbicides were used. These results indicate that glyphosate plus cultivation was not adequate for soybean in stale seedbed plantings, and that either PRE or POST herbicides, but not both, were required for maximum seed yield.


Weed Science ◽  
1979 ◽  
Vol 27 (5) ◽  
pp. 520-526 ◽  
Author(s):  
George Kapusta

Twenty herbicide treatments were evaluated on conventional-till (plow, disc, and harrow), minimum-till (disc only), and no-till planted soybeans [Glycine max(L.) Merr.] from 1976 through 1978 at the Belleville Research Center in St. Clair County, Illinois. The soil type was a Weir silt loam (Typic Ochraqualf) characterized by poor internal drainage and 1.2% organic matter. Weed population by species, weed control, and soybean population, injury, and yield were obtained. Fall panicum (Panicum dichotomiflorumMichx.) and giant foxtail (Setaria faberiHerrm.) were the dominant species in all tillage systems, exceeding 1 million plants/ha in the conventional and no-till plots. These species and ivyleaf morningglory [Ipomoea hederacea(L.) Jacq.] were the most difficult to control each year. Weed control was the poorest in the no-till plots because of the large size of the weeds at the time of herbicide application, insufficient rainfall following, and because the plots were not cultivated. The soybean population was equal in all tillage systems except in 1976 when the no-till population exceeded that in the other tillage systems. Treatments that included oryzalin (3,5-dinitro-N4,N4-dipropylsulfanilamide) caused 42 and 35% soybean injury in the 1976 minimum and no-till plots, respectively. Postemergence-applied naptalam (N-1-naphthylphthalamic acid) plus dinoseb (2-sec-butyl-4,6-dinitrophenol) caused leaf burn each year that ranged from 5 to 35% but all plants recovered within several weeks of application. The seedbed tillage method and herbicide treatments did not significantly affect soybean yields in 1976 when all the herbicides were effective. No-till yields in 1977 and 1978 were substantially lower than yields in conventional and minimum-till plots because of poor weed control. Soybean yields were 2506, 2466, and 1714 kg/ha in the conventional-till, minimum-till, and no-till plots, respectively, when averaged over the 3 yr and 20 herbicide treatments.


1999 ◽  
Vol 13 (3) ◽  
pp. 478-483 ◽  
Author(s):  
Jimmy D. Wait ◽  
William G. Johnson ◽  
Raymond E. Massey

Field studies were conducted at two locations in 1997 and 1998 to evaluate crop injury, weed control, yield, and net economic returns of single and sequential postemergence applications of labeled and reduced rates of glyphosate to no-till, glyphosate-resistant soybean planted in narrow rows. Sequential applications provided at least 91% control of giant foxtail, while single applications provided at least 86% control with labeled rates and 68–93% control with reduced rates. Common waterhemp control was slightly higher with sequential vs. single treatments and with labeled rates vs. reduced rates. Velvetleaf control was greater than 96% with all treatments. Common cocklebur control was 90% or higher with all treatments except a single application of glyphosate at 210 g/ha. Lower control of giant foxtail and common waterhemp with single-application, reduced-rate treatments in two of the four trials resulted in lower yields. Overall, sequential applications, regardless of rate, provided greater weed control, yield, and net income and lower coefficients of variation (C.V.s) of net income than reduced-rate single applications. Single-application treatments showed a trend of decreased weed control, yield, and net income and higher C.V.s of net income with reduced rates of glyphosate.


1993 ◽  
Vol 7 (4) ◽  
pp. 872-878 ◽  
Author(s):  
George Kapusta ◽  
Ronald F. Krausz ◽  
Joseph L. Matthews

Field studies were conducted in 1991 and 1992 to evaluate the duration of giant foxtail control in no-till soybean with MON 13200 alone and with imazaquin applied up to 2 mo prior to planting. MON 13200 at rates ranging from 224 to 448 g ai/ha applied up to 57 d before planting controlled 97 to 99% of giant foxtail averaged over years. MON 13200 plus imazaquin applied approximately 45 or 30 d before planting controlled 92 to 99% of giant foxtail compared with 53, 64, and 65% and 61, 69, and 78% in plots treated with alachlor, metolachlor, or pendimethalin plus imazaquin, respectively. Differences in control of giant foxtail among the herbicides evaluated were minimal when applied 15 or 0 d before planting. Little or no soybean injury was observed in 1991; up to 30% was observed in 1992 but final soybean height was not affected.


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