Influence of Clethodim Application Timing on Control of Volunteer Corn in Soybean

Herbicide options for management of volunteer corn in soybean include a variety of acetyl CoA carboxylase-inhibiting herbicides, yet often, applications of acetyl CoA carboxylase herbicides are delayed until the weed is visible above the soybean canopy. Volunteer corn growing above the soybean canopy is a highly competitive weed, and herbicides applied at this point can kill the weed, yet soybean yield loss is still a concern. Our objective was to compare the effect of controlling various densities of volunteer corn growing in soybean EARLY (≤ 30 cm) versus LATE (≈ 90 cm) on percent control and soybean yield. Seven volunteer corn densities (0, 0.5, 2, 4, 8, 12, and 16 plants m−2) were hand planted into 19-cm row soybean. Clethodim 79 g ai ha−1was tank-mixed with glyphosate at 840 g ae ha−1and applied to the volunteer corn EARLY and LATE. The EARLY application provided higher and less variable control of volunteer corn 14 d after treatment (DAT) compared to LATE applications at all volunteer corn densities. There was no difference in control at 28 DAT for both the EARLY and LATE applications. Soybean yield was not affected by either application timing. Although no yield reduction was seen with the LATE treatments, later-season applications of clethodim to control volunteer corn may offer more variable control and could allow for additional Bt selection pressure on targeted insect pests.

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Palmer Amaranth (Amaranthus palmeri) Interference in Soybeans (Glycine max)

Weed Science ◽

10.1017/s0043174500076888 ◽

1994 ◽

Vol 42 (4) ◽

pp. 523-527 ◽

Cited By ~ 103

Author(s):

Tracy E. Klingaman ◽

Lawrence R. Oliver

Keyword(s):

Glycine Max ◽

Field Study ◽

Palmer Amaranth ◽

Growth And Yield ◽

Yield Reduction ◽

Amaranthus Palmeri ◽

Soybean Yield ◽

Soybean Canopy ◽

Highly Correlated

A 2-yr field study was conducted at Fayetteville, AR, to determine the effect of Palmer amaranth interference on soybean growth and yield. Palmer amaranth density had little effect on soybean height, but soybean canopy width ranged from 77 cm in the weed-free check to 35 cm in plots with 10 plants m–1of row 12 wk after emergence. Soybean yield reduction was highly correlated to Palmer amaranth biomass at 8 wk after emergence and maturity, soybean biomass at 8 wk after emergence, and Palmer amaranth density. Soybean yield reduction was 17, 27, 32, 48, 64, and 68%, respectively, for Palmer amaranth densities of 033, 0.66, 1, 2, 333, and 10 plants m–1of row. Soybean yield reduction and Palmer amaranth biomass were linear to approximately 2 Palmer amaranth m–1of row, suggesting intraspecific interference between adjacent Palmer amaranth is initiated at Palmer amaranth densities between 2 and 3.33 plants m–1of row.

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Common Sunflower (Helianthus annuus) Interference in Soybean (Glycine max)

Weed Technology ◽

10.1017/s0890037x00040021 ◽

1996 ◽

Vol 10 (2) ◽

pp. 317-321 ◽

Cited By ~ 14

Author(s):

Patrick W. Geier ◽

Larry D. Maddux ◽

Loren J. Moshier ◽

Phillip W. Stahlman

Keyword(s):

Dry Matter ◽

Market Price ◽

Yield Reduction ◽

Soybean Yield ◽

Sunflower Plant ◽

Matter Production ◽

Competition Study ◽

Soybean Canopy ◽

Relationship Of ◽

The Relationship

An in-row competition study was conducted in 1991 and 1992 near Silver Lake, KS to determine the relationship of noncultivated common sunflower density to soybean yield, PAR at the soybean canopy, and common sunflower dry matter production. Because of environmental differences, year main effect interactions occurred, so results are presented by year. For example, 0.3 common sunflower plant/m2produced 4030 kg/ha of aboveground dry matter in 1991 and 1300 kg/ha in 1992. Soybean yield reduction ranged from 19 and 17% with 0.3 common sunflower plant/m2to 97 and 95% with 4.6 plant/m2, in 1991 and 1992, respectively. Assuming a treatment cost of $35/ha and a soybean market price of $0.21/kg, economic threshold levels were 0.1 common sunflower plant/m2in 1991, and 0.07 in 1992. Common sunflower at 0.3 plant/m2reduced PAR at the soybean canopy by 390 and 300 μE/m2/s, or 24 and 18% in 1991 and 1992, respectively. We conclude that the ability of common sunflower to intercept PAR above the soybean canopy is an important component in its interference with soybean.

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Control of glyphosate/glufosinate-resistant volunteer corn in corn resistant to aryloxyphenoxypropionates

Weed Technology ◽

10.1017/wet.2020.41 ◽

2020 ◽

Vol 34 (3) ◽

pp. 309-317

Author(s):

Adam Striegel ◽

Nevin C. Lawrence ◽

Stevan Z. Knezevic ◽

Jeffrey T. Krumm ◽

Gary Hein ◽

...

Keyword(s):

Field Experiments ◽

Yield Loss ◽

Production Systems ◽

Yield Reduction ◽

Corn Production ◽

Application Timing ◽

Orthogonal Contrasts ◽

South Central ◽

Resistance Trait ◽

Volunteer Corn

AbstractCorn-on-corn production systems, common in highly productive irrigated fields in South Central Nebraska, can create issues with volunteer corn management in corn fields. EnlistTM corn is a new multiple herbicide–resistance trait providing resistance to 2,4-D, glyphosate, and the aryloxyphenoxypropionate herbicides (FOPs), commonly integrated in glufosinate-resistant germplasm. The objectives of this study were to (1) evaluate ACCase-inhibiting herbicides for glyphosate/glufosinate-resistant volunteer corn control in Enlist corn and (2) evaluate the effect of ACCase-inhibiting herbicide application timing (early POST vs. late POST) on volunteer corn control, Enlist corn injury, and yield. Field experiments were conducted in 2018 and 2019 at South Central Agricultural Laboratory near Clay Center, NE. Glyphosate/glufosinate-resistant corn harvested the year prior was cross-planted at 49,000 seeds ha–1 to mimic volunteer corn in this study. After 7 to 10 d had passed, Enlist corn was planted at 91,000 seeds ha–1. Application timing of FOPs (fluazifop, quizalofop, and fluazifop/fenoxaprop) had no effect on Enlist corn injury or yield, and provided 97% to 99% control of glyphosate/glufosinate-resistant volunteer corn at 28 d after treatment (DAT). Cyclohexanediones (clethodim and sethoxydim; DIMs) and phenylpyrazolin (pinoxaden; DEN) provided 84% to 98% and 65% to 71% control of volunteer corn at 28 DAT, respectively; however, the treatment resulted in 62% to 96% Enlist corn injury and 69% to 98% yield reduction. Orthogonal contrasts comparing early-POST (30-cm-tall volunteer corn) and late-POST (50-cm-tall volunteer corn) applications of FOPs were not significant for volunteer corn control, Enlist corn injury, and yield. Fluazifop, quizalofop, and fluazifop/fenoxaprop resulted in 94% to 99% control of glyphosate/glufosinate-resistant volunteer corn with no associated Enlist corn injury or yield loss; however, quizalofop is the only labeled product as of 2020 for control of volunteer corn in Enlist corn.

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Interference of Wild Poinsettia (Euphorbia heterophylla) with Soybean (Glycine max)

Weed Technology ◽

10.1017/s0890037x00028517 ◽

1994 ◽

Vol 8 (4) ◽

pp. 679-683 ◽

Cited By ~ 7

Author(s):

Teresa S. Willard ◽

James L. Griffin ◽

Daniel B. Reynolds ◽

Arnold M. Saxton

Keyword(s):

Glycine Max ◽

Dry Weight ◽

Growing Season ◽

Field Studies ◽

Yield Reduction ◽

Soybean Yield ◽

Weed Interference ◽

Soybean Canopy ◽

Area Of Influence

Field-studies were conducted over two years to determine the area of influence and duration of interference of wild poinsettia in soybean. Soybean canopy width averaged across years was reduced approximately 10% beginning at 6 wk of interference for both the 0- to 10-and 10-to 20-cm distances from the weed. Soybean dry weights decreased from 14 to 38% within 20 cm of the weed for 12 through 18 wk of interference. In 1990, soybean yield within 10 cm of wild poinsettia was similar to distances of 10 to 20 and 20 to 40 cm, but was less than that for distances greater than 40 cm from the weed. Weed interference resulted in a 9.5% yield reduction in the 0- to 10-cm distance when compared with the 80-to 100-cm distance. In contrast, yield of soybean in 1991 growing within 10 cm of the weed was less than at greater distances, corresponding to an 18% yield reduction when compared with 80 to 100 cm. Differences in wild poinsettia dry weights when growing alone and when growing within the soybean row occurred after 6 and 8 wk of interference in 1990 and 1991, respectively. In 1991 when rainfall during the growing season was twice that of the previous year, canopy width and dry weight of wild poinsettia growing within the soybean row were reduced an average of 57 and 82%, respectively, compared with weeds growing alone.

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