scholarly journals Common lambsquarters (Chenopodium album) interference with corn across the northcentral United States

Weed Science ◽  
2004 ◽  
Vol 52 (6) ◽  
pp. 1034-1038 ◽  
Author(s):  
David W. Fischer ◽  
R. Gordon Harvey ◽  
Thomas T. Bauman ◽  
Sam Phillips ◽  
Stephen E. Hart ◽  
...  
Keyword(s):  
United States ◽  
Field Experiments ◽  
Yield Loss ◽  
Management Decision ◽  
Yield Reduction ◽  
Model Parameters ◽  
Corn Yield ◽  
Data Set ◽  
Common Lambsquarters ◽  
Weed Density

Variation in crop–weed interference relationships has been shown for a number of crop–weed mixtures and may have an important influence on weed management decision-making. Field experiments were conducted at seven locations over 2 yr to evaluate variation in common lambsquarters interference in field corn and whether a single set of model parameters could be used to estimate corn grain yield loss throughout the northcentral United States. Two coefficients (IandA) of a rectangular hyperbola were estimated for each data set using nonlinear regression analysis. TheIcoefficient represents corn yield loss as weed density approaches zero, andArepresents maximum percent yield loss. Estimates of both coefficients varied between years at Wisconsin, andIvaried between years at Michigan. When locations with similar sample variances were combined, estimates of bothIandAvaried. Common lambsquarters interference caused the greatest corn yield reduction in Michigan (100%) and had the least effect in Minnesota, Nebraska, and Indiana (0% yield loss). Variation inIandAparameters resulted in variation in estimates of a single-year economic threshold (0.32 to 4.17 plants m−1of row). Results of this study fail to support the use of a common yield loss–weed density function for all locations.

scholarly journals Stability of corn (Zea mays)-foxtail (Setariaspp.) interference relationships

Weed Science ◽  
1999 ◽  
Vol 47 (2) ◽  
pp. 195-200 ◽  
Author(s):  
John L. Lindquist ◽  
David A. Mortensen ◽  
Philip Westra ◽  
W. J. Lambert ◽  
Thomas T. Bauman ◽  
...  
Keyword(s):  
Weed Management ◽  
Field Experiments ◽  
Yield Loss ◽  
Maximum Yield ◽  
Density Variation ◽  
Corn Yield ◽  
Coefficient Estimates ◽  
Economic Threshold ◽  
Data Set ◽  
The Stability

Variation in interference relationships have been shown for a number of crop-weed associations and may have an important effect on the implementation of decision support systems for weed management. Multiyear field experiments were conducted at eight locations to determine the stability of corn-foxtail interference relationships across years and locations. Two coefficients (IandA) of a rectangular hyperbola equation were estimated for each data set using nonlinear regression procedures. TheIandAcoefficients represent percent corn yield loss as foxtail density approaches zero and maximum percent corn yield loss, respectively. The coefficientIwas stable across years at two locations and varied across years at four locations. Maximum yield loss (A) varied between years at one location. Both coefficients varied among locations. Although 3 to 4 foxtail plants m−-1row was a conservative estimate of the single-year economic threshold (Tc) of foxtail density, variation inIandAresulted in a large variation inTc. Therefore, the utility of using common coefficient estimates to predict future crop yield loss from foxtail interference between years or among locations within a region is limited.

Site-to-site and year-to-year variation inTriticum aestivum–Aegilops cylindricainterference relationships

Weed Science ◽  
1999 ◽  
Vol 47 (5) ◽  
pp. 529-537 ◽  
Author(s):  
Marie Jasieniuk ◽  
Bruce D. Maxwell ◽  
Randy L. Anderson ◽  
John O. Evans ◽  
Drew J. Lyon ◽  
...  
Keyword(s):  
Loss Function ◽  
Field Experiments ◽  
Yield Loss ◽  
Loss Functions ◽  
Parameter Estimates ◽  
Bioeconomic Model ◽  
Data Set ◽  
Weed Density ◽  
Crop Density ◽  
Management Recommendations

Crop yield loss–weed density relationships critically influence calculation of economic thresholds and the resulting management recommendations made by a bioeconomic model. To examine site-to-site and year-to-year variation in winterTriticum aestivumL. (winter wheat)–Aegilops cylindricaHost. (jointed goatgrass) interference relationships, the rectangular hyperbolic yield loss function was fit to data sets from multiyear field experiments conducted at Colorado, Idaho, Kansas, Montana, Nebraska, Utah, Washington, and Wyoming. The model was fit to three measures ofA. cylindricadensity: fall seedling, spring seedling, and reproductive tiller densities. Two parameters:i, the slope of the yield loss curve asA. cylindricadensity approaches zero, anda, the maximum percentage yield loss asA. cylindricadensity becomes very large, were estimated for each data set using nonlinear regression. Fit of the model to the data was better using spring seedling densities than fall seedling densities, but it was similar for spring seedling and reproductive tiller densities based on the residual mean square (RMS) values. Yield loss functions were less variable among years within a site than among sites for all measures of weed density. For the one site where year-to-year variation was observed (Archer, WY), parameteravaried significantly among years, but parameteridid not. Yield loss functions differed significantly among sites for 7 of 10 comparisons. Site-to-site statistical differences were generally due to variation in estimates of parameteri.Site-to-site and year-to-year variation in winterT. aestivum–A. cylindricayield loss parameter estimates indicated that management recommendations made by a bioeconomic model cannot be based on a single yield loss function with the same parameter values for the winterT. aestivum-producing region. The predictive ability of a bioeconomic model is likely to be improved when yield loss functions incorporating time of emergence and crop density are built into the model's structure.

Stability of Corn (Zea mays)-Velvetleaf (Abutilon theophrasti) Interference Relationships

Weed Science ◽  
1996 ◽  
Vol 44 (2) ◽  
pp. 309-313 ◽  
Author(s):  
John L. Lindquist ◽  
David A. Mortensen ◽  
Sharon A. Clay ◽  
Richard Schmenk ◽  
James J. Kells ◽  
...  
Keyword(s):  
Weed Management ◽  
Field Experiments ◽  
Yield Loss ◽  
Abutilon Theophrasti ◽  
Corn Yield ◽  
Critical Component ◽  
Coefficient Estimates ◽  
Data Set ◽  
Weed Interference ◽  
The Stability

The crop-weed interference relationship is a critical component of bioeconomic weed management models. Multi-year field experiments were conducted at five locations to determine the stability of corn-velvetleaf interference relationships across years and locations. Two coefficients (I and A) of a hyperbolic equation were estimated for each data set using nonlinear regression procedures. The I and A coefficients represent percent corn yield loss as velvetleaf density approaches zero, and maximum percent corn yield loss, respectively. The coefficient I was stable across years at two locations, but varied across years at one location. The coefficient A did not vary across years within locations. Both coefficients, however, varied among locations. Results do not support the use of common coefficient estimates for all locations within a region.

Influence of Weed Density and Distribution on Corn (Zea mays) Yield

Weed Science ◽  
1995 ◽  
Vol 43 (2) ◽  
pp. 215-218 ◽  
Author(s):  
Mark J. Vangessel ◽  
Edward E. Schweizer ◽  
Karen A. Garrett ◽  
Philip Westra
Keyword(s):  
Zea Mays ◽  
Grain Yield ◽  
Management Model ◽  
Yield Reduction ◽  
Corn Yield ◽  
Weed Population ◽  
Weed Density ◽  
Weed Distribution ◽  
The Impact

The impact of weed density and weed distribution on irrigated corn yield was investigated in Colorado. Weed densities examined were 0,33,50, or 100% of the indigenous weed population. A series of weed distribution treatments were achieved by varying the length of the weed-free and weedy zones within the corn row while maintaining a constant weed population of 33 or 50% of the indigenous weed level. Grain yield was affected by weed density, but not by weed distribution. Each additional weed reduced corn yield 8.5 and 2.3 kg ha−1in 1991 and 1992, respectively. When corn yields were estimated with a computer weed/corn management model, weed densities 5 to 8 wk after planting provided a better yield reduction estimate than weed densities immediately before harvest.

scholarly journals Effect of nitrogen addition on the comparative productivity of corn and velvetleaf (Abutilon theophrasti)

Weed Science ◽  
2006 ◽  
Vol 54 (02) ◽  
pp. 354-363 ◽  
Author(s):  
Darren C. Barker ◽  
Stevan Z. Knezevic ◽  
Alex R. Martin ◽  
Daniel T. Walters ◽  
John L. Lindquist
Keyword(s):  
Leaf Area ◽  
Field Experiments ◽  
Yield Loss ◽  
Biomass Accumulation ◽  
Nitrogen Addition ◽  
Corn Yield ◽  
N Addition ◽  
Area Index ◽  
Nitrogen Levels ◽  
Weed Growth

Weeds that respond more to nitrogen fertilizer than crops may be more competitive under high nitrogen (N) conditions. Therefore, understanding the effects of nitrogen on crop and weed growth and competition is critical. Field experiments were conducted at two locations in 1999 and 2000 to determine the influence of varying levels of N addition on corn and velvetleaf height, leaf area, biomass accumulation, and yield. Nitrogen addition increased corn and velvetleaf height by a maximum of 15 and 68%, respectively. N addition increased corn and velvetleaf maximum leaf area index (LAI) by up to 51 and 90%. Corn and velvetleaf maximum biomass increased by up to 68 and 89% with N addition. Competition from corn had the greatest effect on velvetleaf growth, reducing its biomass by up to 90% compared with monoculture velvetleaf. Corn response to N addition was less than that of velvetleaf, indicating that velvetleaf may be most competitive at high levels of nitrogen and least competitive when nitrogen levels are low. Corn yield declined with increasing velvetleaf interference at all levels of N addition. However, corn yield loss due to velvetleaf interference was similar across N treatments except in one site–year, where yield loss increased with increasing N addition. Corn yield loss due to velvetleaf interference may increase with increasing N supply when velvetleaf emergence and early season growth are similar to that of corn.

The critical weed-free period in glyphosate-resistant soybean in Ontario is similar to previous estimates using glyphosate-susceptible soybean

2019 ◽  
Vol 99 (4) ◽  
pp. 437-443
Author(s):  
Nader Soltani ◽  
Robert E. Nurse ◽  
Amit J. Jhala ◽  
Peter H. Sikkema
Keyword(s):  
Growth Stage ◽  
Field Experiments ◽  
Yield Loss ◽  
Growth Stages ◽  
Weed Species ◽  
Weed Biomass ◽  
Weed Density ◽  
Weed Interference ◽  
Beginning Of Flowering ◽  
Minimal Reduction

A study consisting of 13 field experiments was conducted during 2014–2016 in southwestern Ontario and southcentral Nebraska (Clay Center) to determine the effect of late-emerging weeds on the yield of glyphosate-resistant soybean. Soybean was maintained weed-free with glyphosate (900 g ae ha−1) up to the VC (cotyledon), V1 (first trifoliate), V2 (second trifoliate), V3 (third trifoliate), V4 (fourth trifoliate), and R1 (beginning of flowering) growth stages, after which weeds were allowed to naturally infest the soybean plots. The total weed density was reduced to 24%, 63%, 67%, 72%, 76%, and 92% in Environment 1 (Exeter, Harrow, and Ridgetown) when soybean was maintained weed-free up to the VC, V1, V2, V3, V4, and R1 soybean growth stages, respectively. The total weed biomass was reduced by 33%, 82%, 95%, 97%, 97%, and 100% in Environment 1 (Exeter, Harrow, and Ridgetown) and 28%, 100%, 100%, 100%, 100%, and 100% in Environment 2 (Clay Center) when soybean was maintained weed-free up to the VC, V1, V2, V3, V4, and R1 stages, respectively. The critical weed-free periods for a 2.5%, 5%, and 10% yield loss in soybean were the V1–V2, VC–V1, and VC–V1 soybean stages in Environment 1 (Exeter, Harrow, and Ridgetown) and V2–V3, V2–V3, and V1–V2 soybean stages in Environment 2 (Clay Center), respectively. For the weed species evaluated, there was a minimal reduction in weed biomass (5% or less) when soybean was maintained weed-free beyond the V3 soybean growth stage. These results shows that soybean must be maintained weed-free up to the V3 growth stage to minimize yield loss due to weed interference.

Growth and Competitiveness of Common Lambsquarters (Chenopodium album) after Foliar Application ofAscochyta caulinaas a Mycoherbicide

Weed Science ◽  
1996 ◽  
Vol 44 (3) ◽  
pp. 609-614 ◽  
Author(s):  
Corné Kempenaar ◽  
Petra J. F. M. Horsten ◽  
Piet C. Scheepens
Keyword(s):  
Sugar Beet ◽  
Dry Matter ◽  
Foliar Application ◽  
Chenopodium Album ◽  
Yield Reduction ◽  
Corn Yield ◽  
Common Lambsquarters ◽  
Leaf Necrosis ◽  
Dry Matter Weight ◽  
Development Application

Control of common lambsquarters by the use ofAscochyta caldinaas a postemergence mycoherbicide was studied in corn and sugar beet, in 1992 or 1993. The weed was planted at determined positions in the crops. Plots were treated with suspensions ofA. caulinaspores, and wetness duration's were varied to create different levels of disease development. Application ofA. caulinaresulted in necrosis development on, and mortality of common lambsquarters. Average severities of leaf necrosis 1 wk after treatment ranged from 0.01 to 0.75. Average proportions of dead plants 3 wk after treatment ranged from 0.00 to 0.65. Necrosis development and mortality were affected by wetness duration in two experiments. Sublethally diseased plants showed reduced growth. Maximum dry matter was affected by crop and by necrosis development. Numbers of fruits per plant showed a positive, almost linear relationship with plant dry matter weight. Seed weight was less affected by necrosis than number of fruits per plant. Competitiveness of common lambsquarters was reduced after infection byA. caulina.Crop dry matter weight showed a positive relationship with the level of common lambsquarters control. In corn, yield reduction by competition was prevented by application of A.caulina, but not in sugar beet.

scholarly journals Modelling temperature variations in polar snow using DAISY

1997 ◽  
Vol 43 (143) ◽  
pp. 180-191 ◽  
Author(s):  
Ε. M. Morris ◽  
H. -P. Bader ◽  
P. Weilenmann
Keyword(s):  
Field Experiments ◽  
A Priori ◽  
Model Parameters ◽  
Data Set ◽  
International Geophysical Year ◽  
Snow Model ◽  
Using Data ◽  
Polar Snow ◽  
Parameter Values ◽  
The Antarctic

AbstractA physics-based snow model has been calibrated using data collected at Halley Bay, Antarctica, during the International Geophysical Year. Variations in snow temperature and density are well-simulated using values for the model parameters within the range reported from other polar field experiments. The effect of uncertainty in the parameter values on the accuracy of the predictions is no greater than the effect of instrumental error in the input data. Thus, this model can be used with parameters determined a priori rather than by optimization. The model has been validated using an independent data set from Halley Bay and then used to estimate 10 m temperatures on the Antarctic Peninsula plateau over the last half-century.

Velvetleaf (Abutilon theophrasti) Effect on Corn (Zea mays) Growth and Yield in South Dakota

1995 ◽  
Vol 9 (4) ◽  
pp. 665-668 ◽  
Author(s):  
Chad Scholes ◽  
Sharon A. Clay ◽  
Kalyn Brix-Davis
Keyword(s):  
South Dakota ◽  
Yield Loss ◽  
Maximum Yield ◽  
Abutilon Theophrasti ◽  
Growth And Yield ◽  
Yield Reduction ◽  
Corn Yield ◽  
Total Biomass ◽  
Area Index ◽  
Large Yield

Studies were conducted at two sites in South Dakota in 1992 and at one site in 1993 to measure the effect of velvetleaf on corn growth and yield. Velvetleaf was overseeded in corn rows and thinned to densities of 0, 1.3, 4, 12, and 24 plants/m2. Velvetleaf leaf area index and total biomass were positively correlated with velvetleaf density. Biomass per velvetleaf plant and corn biomass were correlated negatively with velvetleaf density. The percent corn yield reduction was similar for locations and years in spite of large yield differences. Maximum yield loss estimated by a hyperbolic yield reduction model was 37.2% with a loss of 4.4% per unit velvetleaf density.

Influence of Broadleaf Weeds on Chlorothalonil Deposition, Foliar Disease Incidence, and Peanut (Arachis hypogaea) Yield

1997 ◽  
Vol 11 (1) ◽  
pp. 51-58 ◽  
Author(s):  
Stanley S. Royal ◽  
Barry J. Brecke ◽  
Frederick M. Shokes ◽  
Daniel L. Colvin
Keyword(s):  
Arachis Hypogaea ◽  
Leaf Spot ◽  
Field Experiments ◽  
Yield Loss ◽  
Disease Incidence ◽  
Weed Biomass ◽  
Late Leaf Spot ◽  
Foliar Disease ◽  
Weed Density ◽  
Weed Plants

Field experiments were conducted at Jay and Marianna, FL in 1988 and 1989 to determine the effects of sicklepod, Florida beggarweed, and common cocklebur density on chlorothalonil deposition to peanut foliage, peanut foliar disease incidence, and peanut yield. At a density of four weed plants per 8 m of row, Florida beggarweed and sicklepod reduced chlorothalonil deposition on peanut foliage by 20%, while common cocklebur reduced fungicide deposition by 34%. At the same density, incidence of the foliar diseases early leaf spot and late leaf spot increased 10% with Florida beggarweed, 14% with sicklepod, and 20% with common cocklebur compared with weed-free peanut. The predicted peanut yield loss from a weed density of four plants per 8 m was 16 to 19% for Florida beggarweed, 23 to 25% for sicklepod, and 31 to 39% for common cocklebur. Weed biomass increased with increasing weed density.

Sign in / Sign up

Export Citation Format

Share Document