Influence of Early-Season Yield Loss Predictions from WeedSOFT®and Soybean Row Spacing on Weed Seed Production from a Mixed-Weed Community

2004 ◽  
Vol 18 (2) ◽  
pp. 412-418 ◽  
Author(s):  
Andrew A. Schmidt ◽  
William G. Johnson
Keyword(s):  
Seed Production ◽  
Crop Yield ◽  
Weed Management ◽  
Yield Potential ◽  
Management Decision ◽  
Yield Reduction ◽  
Weed Seed ◽  
Weed Species ◽  
Early Season ◽  
Giant Foxtail

Seed production from weeds that are missed by herbicide application can affect future weed populations and management decisions. It may be possible to expand the utility of computerized weed management decision aids to include an estimate of weed seed production resulting from selected treatments based on crop yield potential. Field studies were conducted in soybean near Columbia, MO, to determine whether weed control recommendations based on crop yield potential from a computerized weed management decision aid influence weed seed production in two soybean row spacings. At approximately 28 d after planting, weed densities and heights were entered into WeedSOFT®to generate a list of treatments ranked by predicted crop yields. Treatments included: (1) highest predicted crop yield in a glyphosate-resistant system, (2) highest predicted crop yield in a nonglyphosate-resistant system, (3) a 10% yield reduction, (4) a 20% yield reduction, and (5) an untreated control. These treatments were applied to soybean grown in 38- and 76-cm rows. Treatments that provided 90% or higher control of an individual species at 22 d after treatment usually produced less seed than untreated checks. Weed seed production based on early-season herbicide efficacy showed a linear relationship and was relatively predictable (r2≥ 0.52) for the predominant weed species. For less dominant weed species, weed seed production was not strongly correlated (r2≤ 0.27) to early-season herbicide efficacy but apparently influenced by control of other weed species. Narrow row spacing reduced giant foxtail biomass both years but did not reduce common ragweed and ivyleaf morningglory biomass. Narrow rows did not decrease giant foxtail, common ragweed, and ivyleaf morningglory seed production.

WeedSOFT: Effects of Corn-Row Spacing for Predicting Herbicide Efficacy on Selected Weed Species

2007 ◽  
Vol 21 (1) ◽  
pp. 219-224 ◽  
Author(s):  
Shawn M. Hock ◽  
Stevan Z. Knezevic ◽  
William G. Johnson ◽  
Christy Sprague ◽  
Alex R. Martin
Keyword(s):  
Crop Yield ◽  
Weed Management ◽  
Crop Yields ◽  
Field Studies ◽  
Yield Potential ◽  
Control Treatment ◽  
Grass Species ◽  
Yield Reduction ◽  
Weed Species ◽  
The North

The ability to accurately estimate herbicide efficacy is critical for any decision-support system used in weed management. Recent efforts by weed scientists in the North Central United States to adopt WeedSOFT across a broad region have resulted in a number of regional research projects designed to assess and improve the predictive capability of WeedSOFT. Field studies were conducted from 2000 to 2002 in Nebraska, Missouri, and Illinois to evaluate herbicide-efficacy predictions made by WeedSOFT in two corn-row spacings. Following crop and weed emergence, input variables, such as weed densities and heights, were entered into WeedSOFT to generate a list of treatments ranked by predicted crop yields. The five treatments evaluated included those predicting highest crop-yield potential (recommended control treatment 1), a 10% yield reduction, a 20% yield reduction, a 10% yield reduction plus cultivation, and cultivation alone. These treatments were applied to corn grown in 38- and 76-cm rows. Generally, treatments applied in 38-cm rows had more accurate herbicide-efficacy predictions compared with 76-cm rows. WeedSOFT provided better control predictions for broadleaf than grass species. WeedSOFT provided excellent herbicide-efficacy predictions for the highest crop-yield potential, which indicates a good potential for practical use of this software for herbicide recommendations.

Management of Avena ludoviciana and Phalaris paradoxa with barley and less herbicide in subtropical Australia

2001 ◽  
Vol 41 (8) ◽  
pp. 1179 ◽  
Author(s):  
S. R. Walker ◽  
G. R. Robinson ◽  
R. W. Medd
Keyword(s):  
Seed Production ◽  
Weed Management ◽  
Field Experiments ◽  
Management Strategies ◽  
Maximum Yield ◽  
Yield Reduction ◽  
Weed Seed ◽  
Tiller Density ◽  
Weed Emergence ◽  
Subtropical Australia

The competitive advantage of barley compared with wheat was quantified for suppressing seed production of Avena ludoviciana Durieu. (wild oats) andPhalaris paradoxa L. (paradoxa grass), and for improving herbicide effectiveness on these major winter grass weeds of the subtropical grain region of Australia. Eight field experiments were broadcast with weed seed before sowing wheat or barley, in which the emerged weeds were then treated with 4 herbicide doses (0, 25, 50, 100% of recommended rates). Yield reduction from untreated weeds was on average 4 times greater in wheat than in barley, with greater losses from A. ludoviciana than P. paradoxa. Barley did not affect weed emergence, but suppressed weed tiller density and, to a lesser extent, the number of weed seeds per tiller. Seed production was, on average, 4340 and 5105 seeds/m2 for A. ludoviciana and P. paradoxa, respectively, in untreated wheat compared with 555 and 50 seeds/m2 in untreated barley. Weed seed production following treatment with 25% herbicide rate in barley was similar or less than that after treatment with 100% herbicide rate in wheat. Overall, 25% herbicide rate was optimal for both conserving yield and minimising weed seed production in barley. For wheat, maximum yield was achieved with 50% herbicide but weed seed production was lowest with 100% herbicide rate. This indicates that weeds can be effectively controlled in barley with considerably less herbicide than required in wheat, highlighting the importance of including barley as a part of weed management strategies that aim to reduce herbicide inputs.

scholarly journals Late-Season Weed Management to Stop Viable Weed Seed Production

Weed Science ◽  
2016 ◽  
Vol 64 (1) ◽  
pp. 112-118 ◽  
Author(s):  
Erin C. Hill ◽  
Karen A. Renner ◽  
Mark J. VanGessel ◽  
Robin R. Bellinder ◽  
Barbara A. Scott
Keyword(s):  
Seed Production ◽  
Weed Management ◽  
Viable Seed ◽  
Weed Seed ◽  
Common Ragweed ◽  
Common Lambsquarters ◽  
Late Season ◽  
Giant Foxtail ◽  
Immature Seeds ◽  
Mature Seeds

Integrated weed management (IWM) for agronomic and vegetable production systems utilizes all available options to effectively manage weeds. Late-season weed control measures are often needed to improve crop harvest and stop additions to the weed seed bank. Eliminating the production of viable weed seeds is one of the key IWM practices. The objective of this research was to determine how termination method and timing influence viable weed seed production of late-season weed infestations. Research was conducted in Delaware, Michigan, and New York over a 2-yr period. The weeds studied included: common lambsquarters, common ragweed, giant foxtail, jimsonweed, and velvetleaf. Three termination methods were imposed: cutting at the plant base (simulating hand hoeing), chopping (simulating mowing), and applying glyphosate. The three termination timings were flowering, immature seeds present, and mature seeds present. Following termination, plants were stored in the field in mesh bags until mid-Fall when seeds were counted and tested for viability. Termination timing influenced viable seed development; however, termination method did not. Common ragweed and giant foxtail produced viable seeds when terminated at the time of flowering. All species produced some viable seed when immature seeds were present at the time of termination. The time of viable seed formation varied based on species and site-year, ranging from plants terminated the day of flowering to 1,337 growing degree d after flowering (base 10, 0 to 57 calendar d). Viable seed production was reduced by 64 to 100% when common lambsquarters, giant foxtail, jimsonweed, and velvetleaf were terminated with immature seeds present, compared to when plants were terminated with some mature seeds present. Our results suggest that terminating common lambsquarters, common ragweed, and giant foxtail prior to flowering, and velvetleaf and jimsonweed less than 2 and 3 wk after flowering, respectively, greatly reduces weed seed bank inputs.

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

2013 ◽  
Vol 27 (1) ◽  
pp. 54-62 ◽  
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.

Implications of weed seedbank dynamics to weed management

Weed Science ◽  
1997 ◽  
Vol 45 (3) ◽  
pp. 329-336 ◽  
Author(s):  
Douglas D. Buhler ◽  
Robert G. Hartzler ◽  
Frank Forcella
Keyword(s):  
Weed Control ◽  
Weed Management ◽  
Plant Ecology ◽  
Management Systems ◽  
Integrated Weed Management ◽  
Management Decision ◽  
Plant Responses ◽  
Weed Seed ◽  
Weed Species ◽  
Tillage Practices

The species composition and density of weed seed in the soil vary greatly and are closely linked to the cropping history of the land. Altering tillage practices changes weed seed depth in the soil, which plays a role in weed species shifts and affects efficacy of control practices. Crop rotation and weed control practices also affect the weed seedbank. Information on the influence of cropping practices on the weed seedbank should be a useful tool for integrated weed management. Decision aid models use information on the weed seedbank to estimate weed populations, crop yield loss, and recommend weed control tactics. Understanding the light requirements of weed seed may provide new approaches to weed management. Improving and applying our understanding of weed seedbank dynamics is essential to developing improved weed management systems. The principles of plant ecology must be integrated with the science of weed management to develop strategies that take advantage of basic plant responses in weed management systems for agronomic crops.

Response of Four Summer Annual Weed Species to Mowing Frequency and Height

2013 ◽  
Vol 27 (4) ◽  
pp. 798-802 ◽  
Author(s):  
RaeLynn A. Butler ◽  
Sylvie M. Brouder ◽  
William G. Johnson ◽  
Kevin D. Gibson
Keyword(s):  
Seed Production ◽  
Weed Management ◽  
Management Practices ◽  
Dry Weight ◽  
Weed Seed ◽  
Weed Species ◽  
Common Lambsquarters ◽  
Giant Ragweed ◽  
Total Dry Weight ◽  
Large Crabgrass

Greenhouse experiments were conducted in 2011 to evaluate the effect of mowing frequency and mowing height on four summer annual weed species (large crabgrass, barnyardgrass, giant ragweed, and common lambsquarters). Plants were clipped at three heights (5, 10, or 20 cm) and at two frequencies (single clipping or repeated clippings at the same height) to simulate mowing. A nonclipped control was also grown for each species. When clipped once, large crabgrass, barnyardgrass, and giant ragweed produced at least 90% of the total dry weight (DW) of the nonclipped plants, and common lambsquarters produced at least 75%. A single cut was generally not sufficient to prevent weed seed production or kill any of the weeds in this study. Repeated clipping reduced large crabgrass, giant ragweed, and common lambsquarters reproductive DW to 46, 27, and 10% respectively, of the nonclipped control. Barnyardgrass plants that were repeatedly clipped produced between 0 and 8% of the seed DW of nonclipped plants, depending on clipping height. Repeated clipping reduced weed total DW to below 40% for all species compared to nonclipped plants. Our results suggest that, unless combined with other weed management practices, repeated mowing may be necessary to limit the growth and seed production of these weed species.

Validation of a Management Program Based on A Weed Cover Threshold Model: Effects on Herbicide Use and Weed Populations

Weed Science ◽  
2009 ◽  
Vol 57 (2) ◽  
pp. 187-193 ◽  
Author(s):  
Marie-Josée Simard ◽  
Bernard Panneton ◽  
Louis Longchamps ◽  
Claudel Lemieux ◽  
Anne Légère ◽  
...  
Keyword(s):  
Seed Production ◽  
Crop Yield ◽  
Weed Management ◽  
Crop Yields ◽  
Threshold Model ◽  
Management Program ◽  
Weed Seed ◽  
Weed Density ◽  
Weed Cover ◽  
Herbicide Use

Weed management decisions based on weed threshold models offer the opportunity to reduce herbicide use by allowing the possibility of forgoing treatment or lowering rates. Weed thresholds based on a relative leaf-cover model were tested during a 4-yr period at two locations. Two 1.62-ha fields, planted to conventional and glyphosate-resistant corn (2004, 2005, 2007) or soybean (2006), were divided in 900 m2sections. Herbicides were applied postemergence to each of these sections with either variable rates based on weed thresholds, or constant full rates. Variable herbicide rates included: no application, half rate, or full rate. Relative weed cover values of 0.2 and 0.4 (corn) or 0.1 and 0.3 (soybean) served as thresholds for incremental rates. Digital images were used to evaluate the relative weed cover. Weed density was assessed before and after herbicide application. Weed seed production was estimated for two species in 2004 and 2005. No difference in crop yield, relative weed cover, weed density, or weed seed production was observed between conventional and glyphosate-resistant cropping systems. During the first year, herbicide use reduction was obtained (−85.4%) with marginal crop yield loss (5 to 15%). In the subsequent 3 yr, preherbicide weed densities increased and concomitant increases in relative weed cover values did not allow more than a 10% overall reduction in herbicide use. This threshold model designed to maintain crop yields within a given year did not allow significant reduction in herbicide use during the following 3 yr. Residual weed populations most likely replenished the seed bank to levels that allowed weed densities to increase afterward. Increased weed density over time in plots treated with full rates of herbicide every year also indicated that a single postemergence herbicide treatment was not sufficient to contain weed populations at low levels every year in this corn–soybean rotation.

Predicting the competitive effects of weed and crop density on weed biomass, weed seed production and crop yield in wheat

Weed Research ◽  
2006 ◽  
Vol 35 (4) ◽  
pp. 265-278 ◽  
Author(s):  
B. J. WILSON ◽  
K. J. WRIGHT ◽  
P. BRAIN ◽  
M. CLEMENTS ◽  
E. STEPHENS
Keyword(s):  
Seed Production ◽  
Crop Yield ◽  
Weed Seed ◽  
Weed Biomass ◽  
Competitive Effects ◽  
Crop Density

scholarly journals Influence of crop rotation, tillage, and management inputs on weed seed production

Weed Science ◽  
1999 ◽  
Vol 47 (2) ◽  
pp. 175-183 ◽  
Author(s):  
George O. Kegode ◽  
Frank Forcella ◽  
Sharon Clay
Keyword(s):  
Seed Production ◽  
Crop Rotation ◽  
Crop Production ◽  
Conservation Tillage ◽  
Farming Systems ◽  
Crop Rotations ◽  
Weed Seed ◽  
Weed Species ◽  
Weed Seeds ◽  
Ridge Tillage

Approaches to crop production that successfully reduce weed seed production can benefit farming systems by reducing management inputs and costs. A 5-yr rotation study was conducted in order to determine the effects that interactions between crop rotation, tillage, and amount of herbicide and fertilizer (management inputs) have on annual grass and broad-leaved weed seed production and fecundity. There were 10 crop rotation and tillage system combinations and three levels of management inputs (high, medium, and low). Green and yellow foxtail were the major weed species, and together they yielded between 76 and 93% of collected weed seeds. From 1990 to 1994, average grass weed seed productions were 7.3 by 103, 3.7 by 1036.1 by 103and 5.7 by 103seeds m−-2, whereas average broad-leaved weed seed productions were 0.4 by 103, 0.4 by 103, 1.4 by 103, and 0.4 by 103seeds m−-2in crop rotations using conventional tillage (moldboard plow), conservation tillage, no tillage, and ridge tillage, respectively. Crop rotations using conventional or ridge tillage consistently produced more grass and broad-leaved weed seeds, especially in low-input plots. There was little difference in weed seed production among input levels for crop rotations using conservation tillage. Comparing rotations that began and ended with a corn crop revealed that by increasing crop diversity within a rotation while simultaneously reducing the amount of tillage, significantly fewer grass and broad-leaved weed seeds were produced. Among the rotations, grass and broad-leaved weed fecundity were highly variable, but fecundity declined from 1990 to 1994 within each rotation, with a concomitant increase in grass and broad-leaved weed density over the same period. Crop rotation in combination with reduced tillage is an effective way of limiting grass and broad-leaved weed seed production, regardless of the level of management input applied.

scholarly journals Relation between Soil Weed Seedbank and Weed Management Practises and Diversity in Farms in Kisii Central Sub County, Nyanza

2020 ◽  
Vol 10 ◽  
pp. 1-14
Author(s):  
Charles N. Nyamwamu ◽  
Rebecca Karanja ◽  
Peter Mwangi
Keyword(s):  
Seed Bank ◽  
Weed Management ◽  
Management Practices ◽  
Soil Seed Bank ◽  
Shannon Index ◽  
Weed Seed ◽  
Weed Species ◽  
Western Kenya ◽  
Weed Diversity ◽  
Hand Weeding

This study sought to determine the relation between soil weed seed bank and weed management practices and diversity in farms in Kisii Central Sub County, Western Kenya. Eight administrative sub-locations were randomly selected. Ten farms were selected at equal distance along transect laid across each sub-location. Weed soil seed bank was assessed from soil samples collected from each of the farms; a sub-sample was taken from a composite sample of ten soil cores of 5cm diameter and 15cm deep and placed in germination trays in a greenhouse. Weed diversity in soil weed seedbank was calculated using the Shannon index (H’). Twelve weed species from 12 genera of nine families were recorded. Diversity of the weed species in soil weed seed bank was (H'=1.48). Weed management practises significantly affected weed species soil weed seedbank reserves. Use of inefficient and ineffective hand-weeding techniques resulted in high weed species diversity and abundance.

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