Wheat (Triticum aestivum) yield reduction from common milkweed (Asclepias syriaca) competition

Weed Science ◽  
1997 ◽  
Vol 45 (1) ◽  
pp. 127-131 ◽  
Author(s):  
Joseph P. Yenish ◽  
Beverly R. Durgan ◽  
Douglas W. Miller ◽  
Donald L. Wyse
Keyword(s):  
Spring Wheat ◽  
Yield Loss ◽  
Root Function ◽  
Wheat Yield ◽  
Shoot Density ◽  
Yield Reduction ◽  
Square Root ◽  
Percentage Yield ◽  
Area Of Influence ◽  
Function Models

Yield loss of hard red spring wheat due to competition from common milkweed was measured in grower fields in Minnesota. Wheat yield loss was measured using the area of influence and additive competitive methods. Simple linear regression of wheat yield and percentage wheat yield loss against distance from a common milkweed shoot gaver2values of 0.013 and 0.015, respectively, indicating limited value of the area of influence model for common milkweed in spring wheat. In an additive competition model, wheat yield was reduced 47% at the highest density of 12 common milkweed shoots m−2. Coefficients of determination for percentage yield loss regressed against common milkweed shoot density were 0.548, 0.547, and 0.529 for simple linear, nonlinear rectangular hyperbolic, and linear square root function models, respectively. Regression of percentage yield loss against common milkweed biomass resulted inr2values of 0.566, 0.645, and 0.658 for simple linear, nonlinear rectangular hyperbolic, and linear square root function models, respectively. Restrictions of common milkweed density due to factors other than competition limited yield loss response to the simple linear phase of both the nonlinear rectangular hyperbolic and the linear square root function models previously described.

Estimating yield losses in wheat resulting from infestation by doublegee (Emex australis)

1974 ◽  
Vol 14 (70) ◽  
pp. 656 ◽  
Author(s):  
DJ Gilbey
Keyword(s):  
Crop Yield ◽  
Field Trial ◽  
Yield Loss ◽  
Wheat Yield ◽  
Yield Reduction ◽  
Yield Losses ◽  
Seedling Mortality ◽  
Emex Australis ◽  
Percentage Yield

The effect of doublegee (Emex australis) density on wheat yield was studied in a field trial. Percentage yield reduction (y) was related to doublegee plants m-2 at 1 week (x1) and 8 weeks (x2) after seeding thus: y = 10.3 + 0.24 x1 r = 0.78*** y = 5.6 + 0.44 x2 r = 0.86*** showing that estimates of doublegee density could be used for forecasting crop yield losses before it is too late to spray. No further yield loss occurred when x1 was greater than 120 plants metre-2. Doublegee seedling mortality that occurred during the seven weeks between plant counts was strongly related to the initial counts (x1) thus: r = 0.88***.

Effects of summer and winter annual scentless chamomile (Matricaria perforata Mérat) interference on spring wheat yield

1991 ◽  
Vol 71 (3) ◽  
pp. 841-850 ◽  
Author(s):  
D. W. Douglas ◽  
A. G. Thomas ◽  
D. P. Peschken ◽  
G. G. Bowes ◽  
D. A. Derksen
Keyword(s):  
Spring Wheat ◽  
Yield Loss ◽  
Wheat Yield ◽  
Weather Conditions ◽  
Yield Reduction ◽  
Hyperbolic Model ◽  
Loss Parameter ◽  
Winter Annuals ◽  
Winter Annual ◽  
Experimental Plots

The influence of summer and winter annual scentless chamomile (Matricaria perforata Mérat) on the yield of spring wheat in Saskatchewan was determined. In experimental plots, spring wheat was seeded into barley stubble where summer and winter annual scentless chamomile had been established. A rectangular hyperbolic model was used to describe the relationship between wheat yield and the density of flowering scentless chamomile plants. Winter annuals caused more yield reduction than did summer annuals. Weather conditions appeared to have an influence on the effect of scentless chamomile on spring wheat yield. The same model was fitted to sample data from farmers' fields and showed yield losses similar to those on the experimental plots. The rectangular hyperbolic model fitted the data best when high weed densities occurred. At densities more typical of those found in farm fields, the asymptotic yield loss parameter of the model was poorly estimated. Key words: Scentless chamomile, Matricaria perforata, yield loss, weed competition, rectangular hyperbola, spring wheat

Yield Loss Assessment for Spring Wheat (Triticum aestivum) Infested with Canada Thistle (Cirsium arvense)

Weed Science ◽  
1992 ◽  
Vol 40 (4) ◽  
pp. 590-598 ◽  
Author(s):  
William W. Donald ◽  
Mohammad Khan
Keyword(s):  
Linear Regression ◽  
Spring Wheat ◽  
Yield Loss ◽  
Wheat Yield ◽  
Growing Season ◽  
Shoot Density ◽  
Regression Equations ◽  
Loss Assessment ◽  
Canada Thistle ◽  
Yield Loss Assessment

In eight of nine trials spanning 5 yr, relative yield of semidwarf hard red spring wheat (yield expressed as a percent of estimated weed-free yield) decreased linearly as Canada thistle shoot density increased when measured in late July to early August in the northern Great Plains. Differences between yield loss assessment (YLA) equations could not be distinguished statistically between no-tillage and chisel-plowed production systems. Multiple linear regression equations of relative wheat yield versus wheat density plus Canada thistle shoot density accounted for more variability in YLA equations than simple linear regression equations of wheat yield versus Canada thistle shoot density alone. Estimated weed-free wheat yield and negative slope (b) for yield loss assessment equations increased as cumulative growing-season (April to August) rainfall increased. Thus, relative wheat yield was decreased more by increasing Canada thistle density (slope b became more negative) in years of greater growing-season rainfall.

Tolerances of wheat cultivars to pre-emergence herbicides

1985 ◽  
Vol 25 (4) ◽  
pp. 922 ◽  
Author(s):  
D Lemerle ◽  
AR Leys ◽  
RB Hinkley ◽  
JA Fisher
Keyword(s):  
Grain Yield ◽  
Spring Wheat ◽  
Yield Loss ◽  
New South ◽  
New South Wales ◽  
Yield Reduction ◽  
Wheat Cultivars ◽  
Yield Losses ◽  
South Wales

Twelve spring wheat cultivars were tested in southern New South Wales for their tolerances to the recommended rates and three times the recommended rates of trifluralin, pendimethalin, tri-allate and chlorsulfuron. Recommended rates of these herbicides did not affect the emergence or grain yield of any cultivar. However, differences between cultivars in their tolerances to trifluralin, pendimethalin and chlorsulfuron at three times the recommended rate were identified. The extent of the reduction in emergence and/or grain yield varied with herbicide and season, and there was also a herbicidexseason interaction. Durati, Songlen and Tincurrin were the most susceptible cultivars to trifluralin, and Teal was the most tolerant. Yield losses from trifluralin were more severe in 1979 than in 1980 or 1981. The differential between cultivars treated with pendimethalin was smaller and more variable; Tincurrin was the only cultivar with a yield reduction in more than one season. Durati, Songlen and Shortim were the only cultivars affected by chlorsulfuron. A reduction in crop emergence of a cultivar treated with trifluralin or pendimethalin did not correlate consistently with any grain yield loss, and reductions in emergence were always greater than yield loss.

Green Foxtail (Setaria viridis) Competition with Spring Wheat (Triticum aestivum)

1992 ◽  
Vol 6 (2) ◽  
pp. 291-296 ◽  
Author(s):  
Dallas E. Peterson ◽  
John D. Nalewaja
Keyword(s):  
Triticum Aestivum ◽  
Spring Wheat ◽  
Field Experiments ◽  
Wheat Yield ◽  
Coefficient Of Determination ◽  
Yield Reduction ◽  
Setaria Viridis ◽  
Hard Red Spring Wheat ◽  
Temperature And Precipitation ◽  
Green Foxtail

Yield reductions due to green foxtail competition with hard red spring wheat varied with environment in field experiments conducted in 1984, 1985, and 1986 at Oakes, Langdon, Prosper, and Fargo, North Dakota. Wheat yield reductions ranged from 0 to 47% from 720 green foxtail plants per m2. Inclusion of early season temperature and precipitation, soil texture, and foxtail density into multiple regression analysis of wheat yield reductions significantly increased the coefficient of determination to 0.62 compared with 0.12 for regression based on green foxtail density alone. Wheat yield reduction decreased as green foxtail seeding was delayed after wheat seeding in 1986. Wheat yield generally decreased as time of diclofop application was delayed from 2 to 6 wk after wheat emergence in 1986.

Carrier Volume Affects Wheat Response to Simulated Glyphosate Drift

2008 ◽  
Vol 22 (3) ◽  
pp. 453-458 ◽  
Author(s):  
Christopher A. Roider ◽  
James L. Griffin ◽  
Stephen A. Harrison ◽  
Curtis A. Jones
Keyword(s):  
Seed Weight ◽  
Field Experiments ◽  
Yield Loss ◽  
Wheat Yield ◽  
Yield Reduction ◽  
Usage Rate ◽  
Height Reduction ◽  
Herbicide Concentration ◽  
Glyphosate Drift ◽  
Carrier Volume

The influence of carrier volume was evaluated in field experiments for glyphosate applied to wheat at rates representing 12.5 and 6.3% of the usage rate of 1,120 g ai/ha (140 and 70 g/ha, respectively). Wheat at first node and at heading was exposed to glyphosate applied in a constant carrier volume of 234 L/ha, where herbicide concentration declined with reduction in dosage, and in proportional carrier volumes of 30 L/ha for the 12.5% rate and 15 L/ha for the 6.3% rate, where herbicide concentration remained constant. At 28 d after treatment, glyphosate applied at first node in proportional carrier volume (an average for 30 and 15 L/ha adjusted proportionally to glyphosate rate) reduced wheat height 42% compared with 15% when glyphosate was applied in 234 L/ha. Height reduction was no more than 15% when glyphosate was applied at heading in 234 L/ha or in the proportional carrier volumes and at first node in 234 L/ha. Wheat yield was reduced 42% when glyphosate at 140 g/ha was applied in 234 L/ha but was reduced 54% for the same rate applied in proportional carrier volume. For 70 g/ha glyphosate, wheat yield was reduced 11% when applied in 234 L/ha, but was reduced 42% when the same rate was applied in proportional carrier volume. Wheat yield reduction was equivalent when glyphosate was applied in 234 L/ha at first node and at heading (29 and 24%, respectively), but yield reductions of 60% for first node application and 36% for heading application were observed when glyphosate was applied in a proportional carrier volume. When averaged across carrier volumes and glyphosate rates, the greater yield loss from application at first node was attributed to decreased number of spikelets per spike and seed weight per spike.

scholarly journals Models for Predicting Potential Yield Loss of Wheat Caused by Stripe Rust in the U.S. Pacific Northwest

2011 ◽  
Vol 101 (5) ◽  
pp. 544-554 ◽  
Author(s):  
D. Sharma-Poudyal ◽  
X. M. Chen
Keyword(s):  
Winter Wheat ◽  
Pacific Northwest ◽  
Stripe Rust ◽  
Spring Wheat ◽  
Yield Loss ◽  
Wheat Yield ◽  
The Other ◽  
Potential Yield ◽  
Highly Correlated ◽  
The U.S

Climatic variation in the U.S. Pacific Northwest (PNW) affects epidemics of wheat stripe rust caused by Puccinia striiformis f. sp. tritici. Previous models only estimated disease severity at the flowering stage, which may not predict the actual yield loss. To identify weather factors correlated to stripe rust epidemics and develop models for predicting potential yield loss, correlation and regression analyses were conducted using weather parameters and historical yield loss data from 1993 to 2007 for winter wheat and 1995 to 2007 for spring wheat. Among 1,376 weather variables, 54 were correlated to yield loss of winter wheat and 18 to yield loss of spring wheat. Among the seasons, winter temperature variables were more highly correlated to wheat yield loss than the other seasons. The sum of daily temperatures and accumulated negative degree days of February were more highly correlated to winter wheat yield loss than the other monthly winter variables. In addition, the number of winter rainfall days was found correlated with yield loss. Six yield loss models were selected for each of winter and spring wheats based on their better correlation coefficients, time of weather data availability during the crop season, and better performance in validation tests. Compared with previous models, the new system of using a series of the selected models has advantages that should make it more suitable for forecasting and managing stripe rust in the major wheat growing areas in the U.S. PNW, where the weather conditions have become more favorable to stripe rust.

Volunteer Barley Interference in Spring Wheat Grown in a Zero-Tillage System

Weed Science ◽  
2007 ◽  
Vol 55 (1) ◽  
pp. 70-74 ◽  
Author(s):  
John T. O'Donovan ◽  
K. Neil Harker ◽  
George W. Clayton ◽  
Linda M. Hall ◽  
Jason Cathcart ◽  
...  
Keyword(s):  
Spring Wheat ◽  
Field Experiments ◽  
Yield Loss ◽  
Wheat Yield ◽  
High Rate ◽  
Initial Slope ◽  
Threshold Values ◽  
Economic Threshold ◽  
Economic Thresholds ◽  
The Impact

There is no published information on the impact of volunteer barley on wheat yield loss or on the economics of controlling barley with a herbicide. With the registration of imazamox-resistant wheat, it is now possible to control volunteer barley in wheat. Thus, the likelihood of growing wheat in rotation with barley may increase. Field experiments were conducted in 2003 and 2004 at Beaverlodge, Lacombe, and Edmonton, AB, Canada, and Saskatoon, SK, Canada, to determine the impact of volunteer barley on yield of imazamox-resistant spring wheat seeded at relatively low (100 kg ha−1) and high (175 kg ha−1) rates. Barley was seeded at different densities to simulate volunteer barley infestations. Regression analysis indicated that wheat-plant density influenced the effects of volunteer barley interference on wheat yield loss, economic threshold values, and volunteer barley fecundity among locations and years. Economic thresholds varied from as few volunteer barley plants as 3 m−2at Beaverlodge in 2003 and 2004 to 48 m−2at Lacombe in 2003. In most cases, wheat yield loss and volunteer barley fecundity were lower and economic thresholds were higher when wheat was seeded at the higher rate. For example, averaged over both years at Beaverlodge initial slope values (percentage of wheat yield loss at low barley density) were 4.5 and 1.7%, and economic threshold values of volunteer barley plants were 3 m−2and 8 m−2at low and high wheat seeding rates, respectively. Results indicate that volunteer barley can be highly competitive in wheat, but yield losses and wheat seed contamination due to volunteer barley can be alleviated by seeding wheat at a relatively high rate.

Competition of Wild Oat in Wheat and Barley

Weed Science ◽  
1968 ◽  
Vol 16 (4) ◽  
pp. 505-508 ◽  
Author(s):  
Allyn R. Bell ◽  
John D. Nalewaja
Keyword(s):  
Triticum Aestivum ◽  
Hordeum Vulgare ◽  
Yield Loss ◽  
Wheat Yield ◽  
Avena Fatua ◽  
Yield Reduction ◽  
Wild Oat ◽  
Phosphorus Fertilizer ◽  
Nitrogen And Phosphorus ◽  
Percent Protein

Wild oat (Avena fatua L.) competition increased the losses in yield of both wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) with increased densities of seedlings. At Fargo in 1965, wild oat densities of 70 and 160 seedlings/sq yd reduced the wheat yield 22.1% and 39.1%, respectively, compared to the wild oat-free check. Similar wild oat densities reduced the barley yield 6.5% and 25.9%, respectively. The addition of nitrogen and phosphorus fertilizer reduced the yield loss caused by wild oat 2 out of 3 years of the experiment. Although a considerable yield reduction occurred in barley and wheat, percent protein and seed size were not influenced noticeably.

Downy Brome (Bromus tectorum) Competition and Control in No-Till Spring Wheat

2013 ◽  
Vol 27 (3) ◽  
pp. 502-508 ◽  
Author(s):  
Michael H. Ostlie ◽  
Kirk A. Howatt
Keyword(s):  
Spring Wheat ◽  
Yield Loss ◽  
Total Yield ◽  
Wheat Yield ◽  
Control Measures ◽  
Downy Brome ◽  
Herbicide Application ◽  
Application Timing ◽  
No Till ◽  
And Control

Downy brome is one of the leading plant pests in winter wheat and no-till spring wheat in many areas of the country. It has recently been studied in North Dakota where it is emerging as a serious crop competitor. Downy brome plants produced up to 60 tillers and more than 7,500 seeds when no control measures were used and densities were less than 2 plants m−2. Experiments focusing on herbicide-application timing identified differences in downy brome control and the grain yield of spring wheat. Regardless of fall or spring application timing, glyphosate applied PRE to wheat completely controlled downy brome in 2007. In 2008, control was not achieved with the earliest glyphosate-application timings because of late-emerging plants. When comparing fall and spring application timings of other herbicides, imazapic provided at least 79% control at each timing and location, resulting in the highest imazamox-resistant spring wheat yield. In general, herbicides performed better when applied in fall than they did when applied in spring. When herbicides were applied POST, imazamox provided the greatest downy brome control and usually caused the largest numerical reduction in downy brome biomass, seed, and stem number. If downy brome was left untreated, regression analysis predicted approximately 2,000 stems m−2could result in total yield loss of spring wheat.

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