Competitiveness with Weeds of Soybean Cultivars with Different Maturity and Canopy Width Characteristics

Field studies were conducted in 2005 at five locations throughout Illinois to determine the effect of maturity date and canopy width characteristics of selected glyphosate-resistant soybean cultivars on competitive ability against weeds. Natural weed populations at all sites were allowed to compete with the soybean cultivars until the V1, V3, V5, or V7 growth stage and then removed with an application of glyphosate. Light-interception readings, weed control ratings, and soybean yield were all measured to compare cultivars. Cultivars of later maturities tended to withstand early season weed competition better and attained higher yields when weeds were removed at later timings than those of earlier maturity. Although canopy width differed moderately among cultivars in some cases, canopy width had no effect on the ability of soybeans to compete with weeds. Thus, choosing soybean cultivars of later maturity might provide more flexibility in weed management and might reduce losses due to weeds, but that benefit needs to be balanced with yield potential.

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Influence of Diclosulam Postemergence Application Timing on Weed Control and Peanut Tolerance

Weed Technology ◽

10.1614/wt-05-087r1.1 ◽

2006 ◽

Vol 20 (3) ◽

pp. 651-657 ◽

Cited By ~ 7

Author(s):

Wesley J. Everman ◽

Scott B. Clewis ◽

Zachary G. Taylor ◽

John W. Wilcut

Keyword(s):

Weed Control ◽

Weed Management ◽

Field Studies ◽

Yield Potential ◽

Yield Response ◽

Early Season ◽

Common Ragweed ◽

Application Timing ◽

Common Lambsquarters ◽

Free Environment

Field studies were conducted at Lewiston–Woodville and Rocky Mount, NC in 2001 and 2002 to evaluate weed control and peanut response to POST treatments of diclosulam at various rates and application timings. Diclosulam controlled common ragweed and entireleaf morningglory when applied within 35 d after planting (DAP). Common ragweed 61 cm tall was controlled ≥92% with 4 to 13 g ai/ha diclosulam and larger common ragweed (107 to 137 cm tall) were controlled ≥97% with 27 g/ha diclosulam. Common lambsquarters was controlled 62% or less with all diclosulam POST treatments following metolachlor applied PRE, which provided 48% control. Peanut injury was less than 15% with all diclosulam POST treatments and was transitory. In separate studies, POST diclosulam treatments did not affect peanut yield in a weed-free environment. Peanut yield in weedy environments was reduced as the diclosulam application timing was delayed because of early season weed interference. A linear relationship was observed between yield and application timing with yield decreasing as application timing was delayed. This yield response documents the importance of early season weed management for maximizing peanut yield potential. Virginia peanut varieties were not affected by different POST rates of diclosulam; however, early season peanut injury showed a linear and quadratic relationship with diclosulam rate and was less than 14% at rates as high as 71 g/ha, and was not apparent by late season.

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Predicted Corn Yield Loss Due to Weed Competition Prior to Postemergence Herbicide Application on Wisconsin Farms

Weed Technology ◽

10.1614/wt-d-12-00097.1 ◽

2013 ◽

Vol 27 (1) ◽

pp. 54-62 ◽

Cited By ~ 18

Author(s):

Nathanael D. Fickett ◽

Chris M. Boerboom ◽

David E. Stoltenberg

Keyword(s):

Weed Management ◽

Yield Loss ◽

Economic Loss ◽

The United States ◽

Yield Potential ◽

Weed Competition ◽

Corn Yield ◽

Herbicide Application ◽

Weed Species ◽

Early Season

Approximately 50% of the genetically modified herbicide-resistant corn hectares in the United States are treated only with POST-applied herbicides for weed management. Although a high degree of efficacy can be obtained with POST-applied herbicides, delayed timing of application may result in substantial corn yield loss. Our goal was to characterize on-farm corn–weed communities prior to POST herbicide application and estimate potential corn-yield loss associated with early-season corn–weed competition. In 2008 and 2009, field surveys were conducted across 95 site-years in southern Wisconsin and recorded weed species, density, and height in addition to crop height, growth stage, and row spacing. WeedSOFT® was used to predict corn yield loss. Common lambsquarters, velvetleaf, dandelion, common ragweed, andAmaranthusspecies were the five most abundant broadleaf weed species across site-years, present in 92, 86, 59, 45, and 44% of all fields, respectively, at mean densities of 19, 3, 3, 4, and 3 plants m−2, respectively. Mean plant heights among these species were 17 cm or less. Grass and sedge species occurred in 96% of fields at a mean density of 25 plants m−2and height of 7 cm. The mean and median of total weed density across site-years were 96 and 52 plants m−2, with heights of 14 and 13 cm, respectively. Mean predicted corn yield loss was 4.5% with a mean economic loss of $62 ha−1. However, predicted yield loss was greater than 5% on one-third of the site-years, with a maximum of 26%. These results indicate that delayed application of POST herbicides has led to corn yield loss due to early-season weed-crop competition on a substantial number of fields across southern Wisconsin, and suggest that management tactics need to be improved to protect corn yield potential fully.

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Weed Management in Wide- and Narrow-Row Glyphosate-Resistant Sugarbeet

Weed Technology ◽

10.1614/wt-d-10-00033.1 ◽

2010 ◽

Vol 24 (4) ◽

pp. 523-528 ◽

Cited By ~ 10

Author(s):

Jon-Joseph Q. Armstrong ◽

Christy L. Sprague

Keyword(s):

Weed Control ◽

Weed Management ◽

Field Studies ◽

Weed Competition ◽

Yield And Quality ◽

Row Width ◽

Herbicide Treatments ◽

Narrow Row

Planting glyphosate-resistant sugarbeet in narrow rows could improve weed control with fewer herbicide applications and cultivations. Field studies were conducted in 2007 and 2008 at multiple locations in Michigan to compare weed management and sugarbeet yield and quality in glyphosate-resistant sugarbeet planted in 38-, 51-, and 76-cm rows. At all locations, weed densities and biomass were less after glyphosate treatments than after conventional herbicide treatments. Weed densities and biomass also were less in 38- and 51-cm rows compared with 76-cm rows following a single glyphosate application when weeds were 10 cm tall. Averaged over row width, sugarbeet treated with glyphosate when weeds first reached 2 cm in height and again as needed thereafter yielded similarly to sugarbeet treated when weeds were 5 to 10 cm tall. However, root yields were reduced when glyphosate application was delayed until weeds averaged 15 cm in height. Sugarbeet root and sugar yields were greater from 38- and 51-cm row widths than from the 76-cm row widths, averaged over all herbicide treatments. Regardless of row width, initial glyphosate applications should be made before weeds reach 10 cm in height to maximize yield and minimize weed competition with sugarbeet.

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Postemergence Control of Italian Ryegrass in Hazelnut Orchards

Weed Technology ◽

10.1017/wet.2021.41 ◽

2021 ◽

pp. 1-22

Author(s):

Marcelo L. Moretti

Keyword(s):

Weed Control ◽

Weed Management ◽

Field Studies ◽

Early Spring ◽

Italian Ryegrass ◽

Specific Response ◽

Record Keeping ◽

Effective Option ◽

Contrast Analysis ◽

Herbicide Use

Abstract Italian ryegrass has become a problematic weed in hazelnut orchards of Oregon because of the presence of herbicide-resistant populations. Resistant and multiple-resistant Italian ryegrass populations are now the predominant biotypes in Oregon; there is no information on which herbicides effectively control Italian ryegrass in hazelnut orchards. Six field studies were conducted in commercial orchards to evaluate Italian ryegrass control with POST herbicides. Treatments included flazasulfuron, glufosinate, glyphosate, paraquat, rimsulfuron, and sethoxydim applied alone or in selected mixtures during early spring when plants were in the vegetative stage. Treatment efficacy was dependent on the experimental site. The observed range of weed control 28 d after treatment was 13 to 76 % for glyphosate, 1 to 72% for paraquat, 58 to 88% for glufosinate, 16 to 97 % for flazasulfuron, 8 to 94% for rimsulfuron, and 25 to 91% for sethoxydim. Herbicides in mixtures improved control of Italian ryegrass compared to single active ingredients based on contrast analysis. Herbicides in mixture increased control by 27% compared to glyphosate, 18% to rimsulfuron, 15% to flazasulfuron, 19% to sethoxydim, and 12% compared to glufosinate when averaged across all sites, but mixture not always improved ground coverage of biomass reduction. This complex site-specific response highlights the importance of record-keeping for efficient herbicide use. Glufosinate is an effective option to manage Italian ryegrass. However, the glufosinate-resistant biotypes documented in Oregon may jeopardize this practice. Non-chemical weed control options are needed for sustainable weed management in hazelnuts.

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The Influence of Weed Management in Wheat (Triticum aestivum) Stubble on Weed Control in Corn (Zea mays)

Weed Technology ◽

10.1017/s0890037x00044249 ◽

1998 ◽

Vol 12 (3) ◽

pp. 522-526 ◽

Cited By ~ 7

Author(s):

Theodore M. Webster ◽

John Cardina ◽

Mark M. Loux

Keyword(s):

Weed Control ◽

Weed Management ◽

Management Practices ◽

Field Studies ◽

Giant Foxtail ◽

Giant Ragweed ◽

Herbicide Treatments ◽

Postharvest Treatment ◽

Full Rate ◽

Wheat Stubble

The objectives of this study were to determine how the timing of weed management treatments in winter wheat stubble affects weed control the following season and to determine if spring herbicide rates in corn can be reduced with appropriately timed stubble management practices. Field studies were conducted at two sites in Ohio between 1993 and 1995. Wheat stubble treatments consisted of glyphosate (0.84 kg ae/ha) plus 2,4-D (0.48 kg ae/ha) applied in July, August, or September, or at all three timings, and a nontreated control. In the following season, spring herbicide treatments consisted of a full rate of atrazine (1.7 kg ai/ha) plus alachlor (2.8 kg ai/ha) preemergence, a half rate of these herbicides, or no spring herbicide treatment. Across all locations, a postharvest treatment of glyphosate plus 2,4-D followed by alachlor plus atrazine at half or full rates in the spring controlled all broadleaf weeds, except giant ragweed, at least 88%. Giant foxtail control at three locations was at least 83% when a postharvest glyphosate plus 2,4-D treatment was followed by spring applications of alachlor plus atrazine at half or full rates. Weed control in treatments without alachlor plus atrazine was variable, although broadleaf control from July and August glyphosate plus 2,4-D applications was greater than from September applications. Where alachlor and atrazine were not applied, August was generally the best timing of herbicide applications to wheat stubble for reducing weed populations the following season.

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Influence of Shading by Soybeans (Glycine max) on Weed Suppression

Weed Science ◽

10.1017/s0043174500063839 ◽

1981 ◽

Vol 29 (5) ◽

pp. 610-615 ◽

Cited By ~ 35

Author(s):

T. R. Murphy ◽

B. J. Gossett

Keyword(s):

South Carolina ◽

Glycine Max ◽

Weed Control ◽

Field Studies ◽

Weed Suppression ◽

Planting Dates ◽

Early Season ◽

Soybean Yield ◽

Annual Weeds

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.

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Stale seedbed weed control in cucumber

Weed Science ◽

10.1017/s0043174500089736 ◽

1998 ◽

Vol 46 (6) ◽

pp. 698-702 ◽

Cited By ~ 11

Author(s):

W. Carroll Johnson ◽

Benjamin G. Mullinix

Keyword(s):

Weed Control ◽

Weed Management ◽

Management System ◽

Field Studies ◽

Management Systems ◽

Yellow Nutsedge ◽

Predominant Species ◽

Combination System ◽

Cucumber Yield

Field studies were conducted from 1995 to 1997 near Tifton, GA, to determine the benefits of stale seedbed weed control in cucumber. Three stale seedbed management systems—(1) power till stale seedbeds twice (2 ×), (2) glyphosate application immediately after planting, and (3) combination system of stale seedbeds power tilled once 2 wk prior to planting followed by glyphosate application immediately after planting cucumber—were evaluated as main plots. Subplots were weed management systems after planting cucumber: intensive, basic, and cultivation alone. Weed densities were generally greater in 1996 and 1997 than in 1995. Yellow nutsedge was the overall predominant species in 1995 (46 plants m−2), with Florida pusley being the predominant species in 1996 and 1997, at 80 and 124 plants m−2, respectively. Generally, stale seedbeds shallow tilled 2 × had fewer weeds and greater cucumber yields than stale seedbeds treated with glyphosate. Glyphosate did not adequately control emerged Florida pusley on stale seedbeds, resulting in reduced cucumber yield. Clomazone preemergence and bentazon/halosulfuron postemergence were used for broadleaf weed control in the intensive weed management system. These herbicides injured cucumber plants, delayed maturity, and reduced yield. Based on our results, stale seedbeds shallow tilled 2 × can be integrated into cucumber production and provide effective cultural weed control. Furthermore, these systems will replace the need for potentially injurious herbicides.

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Weed Control Efficacy and Pinto Bean (Phaseolus vulgaris) Tolerance to Early Season Mechanical Weeding

Weed Technology ◽

10.1017/s0890037x00023800 ◽

1995 ◽

Vol 9 (3) ◽

pp. 531-534 ◽

Cited By ~ 8

Author(s):

Mark J. Vangessel ◽

Lori J. Wiles ◽

Edward E. Schweizer ◽

Phil Westra

Keyword(s):

Phaseolus Vulgaris ◽

Weed Control ◽

Weed Management ◽

Seed Weight ◽

Growth Stage ◽

Integrated Approach ◽

Growth Stages ◽

Weed Species ◽

Control Efficacy ◽

Pinto Bean

An integrated approach to weed management in pinto bean is needed since available herbicides seldom adequately control all weed species present in a field. A two-year study was conducted to assess weed control efficacy and pinto bean tolerance to mechanical weeding from a rotary hoe or flex-tine harrow at crook, unifoliolate, and trifoliolate stages of bean development. Weed control was similar for both implements and all timings in 1993. In 1994, mechanical weeding at trifoliolate and both crook and trifoliolate stages controlled more weeds than at other growth stages, regardless of type of implement. Using the flex-tine harrow reduced pinto bean stand, but results based on growth stage were not consistent each year. Damage to pinto bean hypocotyls and stems was observed with the flex-tine harrow used at both crook and trifoliolate stages in 1994. Rotary hoeing did not reduce pinto bean stand or cause injury. Yield and seed weight did not differ among treatments in either year.

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Herbicide Performance in Rice (Oryza sativa) under Three Flooding Conditions

Weed Science ◽

10.1017/s0043174500058719 ◽

1984 ◽

Vol 32 (2) ◽

pp. 157-162 ◽

Cited By ~ 17

Author(s):

Edward P. Richard ◽

Joe E. Street

Keyword(s):

Oryza Sativa ◽

Drought Stress ◽

Weed Control ◽

Weed Competition ◽

Yield Losses ◽

Early Season ◽

Rice Yields ◽

Weed Emergence ◽

Principal Advantage

A 3-yr study was conducted to compare the performance of several herbicides applied alone and in mixtures under three flooding conditions in dry-seeded rice (Oryza sativaL. ‘Labelle’). When the soil remained moist during the 2-week unflooded periods (1979 and 1981), weed emergence was slowed and no advantage with respect to enhanced weed control and increased rice yields could be demonstrated over that of the standard sequential propanil (3′,4′-dichloropropionanilide) application. However, in 1980 when drought stress may have reduced initial postemergence activity and weeds emerged during the 14-day unflooded periods, differences in weed control between herbicides were obtained. Results of this study also indicate that yield losses from weed competition resulted primarily from early season competition, and that the principal advantage of the residual herbicides in dry-seeded rice may be to eliminate the need for retreatment with propanil when flooding is delayed or fields are drained.

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Weed management with CGA-362622 in transgenic and nontransgenic cotton

Weed Science ◽

10.1614/p2002-014 ◽

2003 ◽

Vol 51 (6) ◽

pp. 1002-1009 ◽

Cited By ~ 19

Author(s):

Dunk Porterfield ◽

John W. Wilcut ◽

Jerry W. Wells ◽

Scott B. Clewis

Keyword(s):

North Carolina ◽

Weed Control ◽

Weed Management ◽

Field Studies ◽

Palmer Amaranth ◽

Management Systems ◽

Weed Species ◽

Crop Tolerance ◽

Prickly Sida ◽

Smooth Pigweed

Field studies conducted at three locations in North Carolina in 1998 and 1999 evaluated crop tolerance, weed control, and yield with CGA-362622 alone and in combination with various weed management systems in transgenic and nontransgenic cotton systems. The herbicide systems used bromoxynil, CGA-362622, glyphosate, and pyrithiobac applied alone early postemergence (EPOST) or mixtures of CGA-362622 plus bromoxynil, glyphosate, or pyrithiobac applied EPOST. Trifluralin preplant incorporated followed by (fb) fluometuron preemergence (PRE) alone or fb a late POST–directed (LAYBY) treatment of prometryn plus MSMA controlled all the weed species present less than 90%. Herbicide systems that included soil-applied and LAYBY herbicides plus glyphosate EPOST or mixtures of CGA-362622 EPOST plus bromoxynil, glyphosate, or pyrithiobac controlled broadleaf signalgrass, entireleaf morningglory, large crabgrass, Palmer amaranth, prickly sida, sicklepod, and smooth pigweed at least 90%. Only cotton treated with these herbicide systems yielded equivalent to the weed-free check for each cultivar. Bromoxynil systems did not control Palmer amaranth and sicklepod, pyrithiobac systems did not control sicklepod, and CGA-362622 systems did not control prickly sida.

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