Field evaluation of regression equations to estimate crop yield losses due to weeds

2005 ◽  
Vol 85 (4) ◽  
pp. 955-962 ◽  
Author(s):  
J. T. O’Donovan ◽  
R. E. Blackshaw ◽  
K. N. Harker ◽  
G. W. Clayton ◽  
D. C. Maurice
Keyword(s):  
Triticum Aestivum L ◽  
Regression Equations ◽  
Wild Oat ◽  
Economic Threshold ◽  
Herbicide Application ◽  
Hordeum Vulgare L ◽  
Relative Time ◽  
Brassica Napus L ◽  
Weed Density ◽  
Crop Density

Various regression equations based on weed density alone, or relative time of weed and crop emergence or crop density in addition to weed density have been developed in western Canada to estimate the effects of wild oat (Avena fatua L.) and volunteer cereals on yield loss of field crops, and to advise farmers on the economics of weed control with herbicides. In 1997, 1998, and 1999, several of these equations were evaluated in 9 barley (Hordeum vulgare L.), 9 wheat (Triticum aestivum L.) and 11 canola (Brassica napus L.) fields in Alberta. Wild oat was the dominant weed in the barley and wheat fields, and wild oat or volunteer cereals in the canola fields. In barley and wheat, more complex equations based on both weed density and either crop density or relative time of weed and crop emergence were more reliable in estimating yield losses due to wild oat than those based on weed density alone. In canola, an equation based on volunteer barley and canola density provided the most reliable estimates. Under the assumed crop prices and herbicide costs, these equations also resulted in the best estimates of whether or not a herbicide application resulted in a net profit or loss. Herbicide application was rarely economical in barley, but usually economical in wheat and canola reflecting the different market value of the crops. The implementation of the weed economic threshold concept is likely to be more feasible in low-value crops such as feed barley than in higher-value crops such as canola. Key words: Barley (Hordeum vulgare L.), canola (Brassica napus L.), volunteer cereals, weed economic threshold, wheat (Triticum aestivum L.), wild oat (Avena fatua L.)

Site-specific wild oat (Avena fatua L.) management

2012 ◽  
Vol 92 (5) ◽  
pp. 923-931 ◽  
Author(s):  
H. J. Beckie ◽  
S. Shirriff
Keyword(s):  
Specific Treatment ◽  
Triticum Aestivum L ◽  
Avena Fatua ◽  
Slope Position ◽  
Wild Oat ◽  
Herbicide Application ◽  
Brassica Napus L ◽  
Site Specific ◽  
Lower Slope ◽  
Upper Slope

Beckie, H. J. and Shirriff, S. 2012. Site-specific wild oat ( Avena fatua L.) management. Can. J. Plant Sci. 92: 923–931. Variation in soil properties, such as soil moisture, across a hummocky landscape may influence wild oat emergence and growth. To evaluate wild oat emergence, growth, and management according to landscape position, a study was conducted from 2006 to 2010 in a hummocky field in the semiarid Moist Mixed Grassland ecoregion of Saskatchewan. The hypothesis tested was that wild oat emergence and growth would be greater in lower than upper slope positions under normal or dry early growing season conditions. Three herbicide treatments were imposed on the same plots each year of a 2-yr canola (Brassica napus L.) – wheat (Triticum aestivum L.) sequence: (1) nontreated (weedy) control; (2) herbicide application to upper and lower slope positions (i.e., full or blanket application); and (3) herbicide application to lower slope position only. Slope position affected crop and weed densities before in-crop herbicide application in years with dry spring growing conditions. Site-specific wild oat herbicide application in hummocky fields in semiarid regions may be justified based on results of wild oat control averaged across slope position. In year 2 of the crop sequence (wheat), overall (i.e., lower and upper slope) wild oat control based on density, biomass, and dockage (i.e., seed return) was similar between site-specific and full herbicide treatment in 2 of 3 yr. Because economic thresholds have not been widely adopted by growers in managing wild oat, site-specific treatment in years when conditions warrant may be an appropriate compromise between no application and blanket herbicide application.

GROWTH OF BARLEY, BROMEGRASS AND ALFALFA IN THE GREENHOUSE IN SOIL CONTAINING RAPESEED AND WHEAT RESIDUES

1978 ◽  
Vol 58 (1) ◽  
pp. 241-248 ◽  
Author(s):  
J. WADDINGTON
Keyword(s):  
Triticum Aestivum ◽  
Brassica Napus ◽  
Hordeum Vulgare ◽  
Wheat Straw ◽  
Nitrogen Deficiency ◽  
Triticum Aestivum L ◽  
Bromus Inermis ◽  
Hordeum Vulgare L ◽  
Total Leaf Area ◽  
Brassica Napus L

Under greenhouse conditions, incorporating ground straw in the soil at rates between 2,240 and 8,970 kg/ha reduced the emergence of alfalfa (Medicago media Pers. cv. Beaver) significantly (P < 0.05) and bromegrass (Bromus inermis Leyss cv. Magna) slightly, but had no effect on barley (Hordeum vulgare L. cv. Conquest). Rape (Brassica napus L. cv. Target and B. campestris L. cv. Echo) straws were more damaging than wheat (Triticum aestivum L. cv. Manitou) straw. Symptoms of severe nitrogen deficiency appeared early in the growth of barley where straw had been added to the soil. The effect on tillering varied. In one experiment tillers were smaller, in one tillers were larger; but in both, total leaf area produced was much less where 8,970 kg/ha of straw had been added to the soil. Bromegrass showed the same effects but to a lesser degree, probably because of slower growth requiring a smaller supply of nitrogen. Alfalfa growth was apparently unaffected. There was no evidence that the straw of either rapeseed species was more deleterious than wheat straw to crop growth after emergence. It is concluded that straw incorporated in soil affected barley and bromegrass growth by reducing the availability of nitrogen.

scholarly journals Research on the Allelophatic Effect Between the Invasive Species Ambrosia Artemisiifolia L. (“Floarea Pustei”) and Some Agricultural Crops

1970 ◽  
Vol 66 (1) ◽  
Author(s):  
Nicolae HODIŞAN ◽  
Gavrilă MORAR ◽  
Cristina-Maria NEAG
Keyword(s):  
Invasive Species ◽  
Triticum Aestivum L ◽  
Ambrosia Artemisiifolia ◽  
Allelopathic Effect ◽  
Hordeum Vulgare L ◽  
Brassica Napus L ◽  
Crop Species ◽  
Inhibiting Effect ◽  
Secale Cereale L ◽  
Germination And Growth

The paper presents the results of the allelopathic effect on the germination and growth of plants, immediately after springing, in the interaction between the invasive species Ambrosia artemisiifolia L. (common ragweed) and five crop species: wheat (Triticum aestivum L.), rye (Secale cereale L.), barley (Hordeum vulgare L.), rape (Brassica napus L.) and lucerne (Medicago sativa). The tests consisted in applying treatments with aqueous extracts obtained from young Ambrosia artemisiifolia L. plants, as well as from different vegetative organs harvested from mature plants (roots, leaves and seeds). The results show a highly significant inhibiting effect on the germination of wheat, rye, barley and rape seeds and an insignificant one in lucerne seeds. A strong inhibiting effect upon the growth of plants in early stages of vegetation was established in wheat and rape and a stimulation of growth in the same stage of vegetation in barley and lucerne.

scholarly journals Results of the Research on the Allelopathic Effect Between the Neophyte Species, Iva Xanthiifolia Nutt. (“Ierboaia”) and Some Agricultural Crops

1970 ◽  
Vol 66 (1) ◽  
Author(s):  
Nicolae HODIŞAN
Keyword(s):  
Primary Source ◽  
Triticum Aestivum L ◽  
Ambrosia Artemisiifolia ◽  
Allelopathic Effect ◽  
Aqueous Extracts ◽  
Hordeum Vulgare L ◽  
Brassica Napus L ◽  
Vegetative Organs ◽  
Secale Cereale L ◽  
Germination And Growth

Iva xanthiifolia Nutt., popularly known as “ierboaie”, is a neophyte invasive species notorious for being an allergenic weed, identified in the west of Romania, in two locations near Oradea, in Bihor County, near the border with Hungary. This species belongs to the allergenic weeds, being considered by some even more dangerous than Ambrosia artemisiifolia L., the two representing in summer the primary source of allergies, or diseases like hay fever, due to the pollen released in the atmosphere.The research is about the results of the allelophatic effect upon the germination and growth of plants, immediately after springing, viewed as the interaction between the species of Iva xanthiifolia and five other crop plants: wheat (Triticum aestivum L.), rye (Secale cereale L.), barley (Hordeum vulgare L.), rape (Brassica napus L.) and lucerne (Medicago sativa). The experiments that were performed consisted in applying treatments with aqueous extracts obtained from different vegetative organs (roots, leaves, stems and seeds) harvested from Iva xanthiifolia plants. In all cases, the results indicate a rather large inhibitor effect, no matter if the aqueous extracts were obtained from green plants or dehydrated ones.

EFFECTS OF POST-EMERGENCE WILD OAT HERBICIDES ON THE TRANSPIRATION OF WILD OATS

1977 ◽  
Vol 57 (1) ◽  
pp. 127-132 ◽  
Author(s):  
M. P. SHARMA ◽  
W. H. VANDEN BORN ◽  
D. K. McBEATH
Keyword(s):  
Triticum Aestivum ◽  
Acid Methyl Ester ◽  
Dry Weight ◽  
Triticum Aestivum L ◽  
Avena Fatua ◽  
Wild Oat ◽  
Hordeum Vulgare L ◽  
Wild Oats ◽  
Acid Methyl ◽  
Foliar Treatment

Transpiration of wild oat (Avena fatua L.) plants was markedly reduced after foliar treatment with barban (4-chloro-2-butynyl-m-chlorocarbanilate), asulam (methyl sulfanylcarbamate), dichlorfop methyl (4-(2′,4′-dichlorophenoxy)-phenoxypropionic acid methyl ester), difenzoquat (1,2-dimethyl-3,5-diphenyl-1 H-pyrazolium) or benzoylprop ethyl (ethyl-N-benzoyl-N(3,4-dichlorophenyl)-2-aminopropionate). Suppression of transpiration increased with increasing herbicide rates. Difenzoquat and dichlorfop methyl at 1.12 kg/ha reduced transpiration by more than 50% within 2 days after spraying. Barban, asulam and benzoylprop ethyl did not reduce transpiration to this level until about 12 days after spraying. When wild oats and barley (Hordeum vulgare L.) or wheat (Triticum aestivum L.) were grown together, removal of the weed with these herbicides resulted in significantly heavier barley and wheat plants with more tillers per plant than in the untreated control. The earlier removal of wild oat competition with dichlorfop methyl and difenzoquat treatments resulted in the production of more dry weight and culms per plant of barley and wheat than with the slower-acting barban and benzoylprop ethyl.

The use of Biologically Realistic Equations to Describe the Effects of Weed Density and Relative Time of Emergence on Crop Yield

Weed Science ◽  
1987 ◽  
Vol 35 (5) ◽  
pp. 720-725 ◽  
Author(s):  
Roger Cousens ◽  
Philip Brain ◽  
John T. O'Donovan ◽  
P. Ashley O'Sullivan
Keyword(s):  
Seedling Emergence ◽  
Multiple Regression Model ◽  
Regression Coefficients ◽  
Published Data ◽  
Wild Oat ◽  
Relative Time ◽  
Yield Increase ◽  
Weed Density ◽  
Image Position ◽  
The Relationship

A model, based on a rectangular hyperbola, has been developed to describe the relationship between population density and relative time of seedling emergence of wild oat (Avena fatuaL. # AVEFA) and yield of barley (Hordeum vulgareL.) and wheat (Triticum aestivumL.). The equation iswhere yLis percent yield loss, D is weed density, T is relative time of emergence of weed and crop, and a, b, and c are nonlinear regression coefficients. Significant differences in fitted equations were found between years. From the values of regression coefficients it was concluded that barley is a better competitor than wheat and is less affected by late-emerging wild oat. The model was tested on previously published data. It provided only a slightly better description of the data than a multiple-regression model, but avoided a number of undesirable, implausible properties inherent in the more frequently used approach. In particular, the model does not predict a loss in yield when no weeds are present or a yield increase from late-emerging weeds.

scholarly journals The convergent evolution of aluminium resistance in plants exploits a convenient currency

2010 ◽  
Vol 37 (4) ◽  
pp. 275 ◽  
Author(s):  
Peter R. Ryan ◽  
Emmanuel Delhaize
Keyword(s):  
Protein Function ◽  
Convergent Evolution ◽  
Oryza Sativa L ◽  
Triticum Aestivum L ◽  
Organic Anions ◽  
Plant Production ◽  
Hordeum Vulgare L ◽  
Brassica Napus L ◽  
Secale Cereale L ◽  
Aluminium Resistance

Suspicions that soluble aluminium (Al) is detrimental to plant growth were reported more than 100 years ago. The rhizotoxicity of Al3+ is now accepted as the major limitation to plant production on acidic soils. Plants differ in their susceptibility to Al3+ toxicity and significant variation can occur within species, even in some major crops. The physiology of Al3+ resistance in some species has been understood for 15 years but the molecular biology has been elucidated only recently. The first gene controlling Al3+ resistance was cloned from wheat (Triticum aestivum L.) in 2004 but others have now been identified in Arabidopsis, barley (Hordeum vulgare L.), rye (Secale cereale L.), sorghum (Sorghum bicolour (L.) Moench) and rice (Oryza sativa L.) with strong additional candidates in wheat and oilseed rape (Brassica napus L.). These genes confer resistance in different ways, but one mechanism occurs in nearly all species examined so far. This mechanism relies on the release of organic anions from roots which bind with the harmful Al3+ cations in the apoplast and detoxify them. The genes controlling this response come from at least two distinct families, suggesting that convergent evolution has occurred. We discuss the processes driving this convergence of protein function and offer opinions for why organic anions are central to the mechanisms of resistance in disparate species. We propose that mutations which modify protein expression or their activation by Al3+ have played important roles in co-opting different transport proteins from other functions.

scholarly journals Pests and diseases in a changing climate a major challenge for Finnish crop production

2008 ◽  
Vol 20 (1) ◽  
pp. 3 ◽  
Author(s):  
K. HAKALA ◽  
A.O. HANNUKKALA ◽  
E. HUUSELA-VEISTOLA
Keyword(s):  
Crop Production ◽  
Growing Season ◽  
Triticum Aestivum L ◽  
Climatic Conditions ◽  
Production Potential ◽  
Physical Damage ◽  
Hordeum Vulgare L ◽  
Brassica Napus L ◽  
Crop Species ◽  
Pests And Diseases

A longer growing season and higher accumulated effective temperature sum (ETS) will improve crop production potential in Finland. The production potential of new or at present underutilised crops (e.g. maize (Zea mays L.), oilseed rape (Brassica napus L.), lucerne (Medicago sativa L.)) will improve and it will be possible to grow more productive varieties of the currently grown crops (spring wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), oats (Avena sativa L.)). Also cultivation of autumn sown crops could increase if winters become milder and shorter, promoting overwintering success. Climatic conditions may on the other hand become restrictive in many ways. For example, early season droughts could intensify because of higher temperatures and consequent higher evaporation rates. Current low winter temperatures and short growing season help restrict the development and spread of pests and pathogens, but this could change in the future. Longer growing seasons, warmer autumns and milder winters may initiate new problems with higher occurrences of weeds, pests and pathogens, including new types of viruses and virus vectors. Anoxia of overwintering crops caused by ice encasement, and physical damage caused by freezing and melting of water over the fields may also increase. In this study we identify the most likely changes in crop species and varieties in Finland and the pest and pathogen species that are most likely to create production problems as a result of climate change during this century.;

CONTROL OF WILD OATS IN WHEAT WITH BENZOYLPROP-ETHYL

1975 ◽  
Vol 55 (2) ◽  
pp. 379-383 ◽  
Author(s):  
P. N. P. CHOW ◽  
R. D. DRYDEN
Keyword(s):  
Acetic Acid ◽  
Leaf Growth ◽  
Good Control ◽  
Triticum Aestivum L ◽  
Wild Oat ◽  
Liquid Formulation ◽  
Herbicide Application ◽  
Early Application ◽  
Wild Oats ◽  
Dichlorophenoxy Acetic Acid

Benzoylprop-ethyl (ethyl-N-benzoyl-N (3,4-dichlorophenyl)-2-amino-propionate) at 1.1 to 5.5 kg/ha gave good control of wild oats (Avena fatua L.) resulting in significantly higher yields of wheat (Triticum aestivum L. cv. Manitou and Neepawa). Late herbicide application (4-leaf growth stage of wild oats) provided better wild oat control and slightly better wheat yields than early application (1.5-leaf stage) in 1969 but not in 1970. Of the three herbicide formulations evaluated, the FX 2182 liquid formulation gave slightly higher wheat yields. Benzoylprop-ethyl at 1.4 kg/ha in mixture with TCA (sodium salt of trichloroacetic acid) at 0.56 kg/ha was less effective in controlling wild oats than benzoylprop-ethyl alone, but wheat yields were unaffected. However, addition of the amine salt of 2,4-D ((2,4-dichlorophenoxy) acetic acid) or MCPA ([(4-chloro-o-tolyl) oxy] acetic acid) at 0.56 kg/ha to benzoylprop-ethyl/TCA mixtures significantly reduced the efficiency of benzoylprop-ethyl for wild oat control and reduced wheat tolerance resulting in lower yields.

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