Development of equations for estimating yield losses caused by multi-species weed communities dominated by green foxtail [Setaria viridis (L.) Beauv.]

1993 ◽  
Vol 73 (2) ◽  
pp. 625-635 ◽  
Author(s):  
L. Hume
Keyword(s):  
Multiple Regression ◽  
Spring Wheat ◽  
Dry Weight ◽  
Crop Loss ◽  
Regression Equations ◽  
Setaria Viridis ◽  
Important Species ◽  
Weed Communities ◽  
Green Foxtail ◽  
Crop Density

Multiple regression equations were developed to describe the relationship between percentage hard red spring wheat (Triticum aestivum L.) loss and the density and shoot dry weight of multi-species weed communities dominated by green foxtail [Setaria viridis (L.) Beauv.]. Data were collected over a 10-yr period from fields sown by farmers near Regina, Saskatchewan. Weed densities averaged 470 plants m−2, with green foxtail constituting 85% of the total number of plants and 57% by dry weight. Other important species included in the equations were stinkweed (Thlaspi arvense L.), common lamb’s-quarters (Chenopodium album L.), wild buckwheat (Polygonum convolvulus L.), and wild mustard (Sinapis arvensis L.). Including crop density as a variable made a significant improvement in the efficiency of the equations. Precipitation and growing degree-days (base 5 °C) were related to the residuals from the analysis relating wheat loss to weed abundance. These environmental variables were significantly related to crop loss, but only for the residuals of the equation where weed densities were used as independent variables. Hyperbolic and sigmoidal equations were less efficient at describing the data than were multiple linear regression equations. Key words: Green foxtail, spring wheat, competition, multi-species, multiple regression, crop loss

YIELD LOSSES IN WHEAT DUE TO WEED COMMUNITIES DOMINATED BY GREEN FOXTAIL [Setaria viridis (L.) BEAUV.]: A MULTISPECIES APPROACH

1989 ◽  
Vol 69 (2) ◽  
pp. 521-529 ◽  
Author(s):  
L. HUME
Keyword(s):  
Yield Loss ◽  
Triticum Aestivum L ◽  
Crop Loss ◽  
Setaria Viridis ◽  
Yield Losses ◽  
Degree Days ◽  
Relative Time ◽  
Weed Communities ◽  
Green Foxtail ◽  
Multispecies Competition

A model was developed to predict wheat (Triticum aestivum L.) loss due to interference by multi-species weed communities dominated by green foxtail [Setaria viridis (L.) Beauv.], 3–4 wk after seeding. Results indicated that green foxtail-dominated weed communities averaging 427 plants m−2 over 4 yr reduced yield by about 7.8%. When plots were kept free of green foxtail, different species became important components of a second model developed to predict the yield loss. The combined effect of precipitation and growing degree days was an important component of both models. It is postulated that these environmental variables reflected the relative time of emergence of the weeds and the crop. Advantages of models based upon multispecies tests over those determined from one-weed one-crop tests are discussed as they relate to crop loss in multispecies situations.Key words: Setaria viridis, green foxtail, crop loss, multispecies competition, weed communities, modeling

Effect of Seeding Dates and Densities of Green Foxtail (Setaria viridis) on the Growth and Productivity of Spring Wheat (Triticum aestivum)

Weed Science ◽  
1981 ◽  
Vol 29 (2) ◽  
pp. 212-217 ◽  
Author(s):  
R. E. Blackshaw ◽  
E. H. Stobbe ◽  
A. R. W. Sturko
Keyword(s):  
Triticum Aestivum ◽  
Spring Wheat ◽  
Dry Weight ◽  
Early Growth ◽  
Tiller Number ◽  
Setaria Viridis ◽  
Normal Height ◽  
Wheat Growth ◽  
Green Foxtail ◽  
Soil Temperature And Moisture

Competition of green foxtail [Setaria viridis(L.) Beauv.] was studied in a semi-dwarf wheat (Triticum aestivumL. ‘Norquay’) and in two normal-height wheats (‘Napayo’ and ‘Sinton’) from 1975 through 1978. Green foxtail suppressed wheat growth as well as grain yield. Tiller number, leaf area, and dry weight of wheat were reduced. Green foxtail was more competitive in the semi-dwarf variety than in either normal height variety. The intensity of green foxtail competition could not be determined by density alone. In 1975, as few as 100 green foxtail plants/m2significantly reduced yield of Napayo and Norquay wheat by 21 and 44%, respectively. In 1977, however, 1600 green foxtail plants/m2did not reduce the yield of Sinton wheat significantly. The intensity of green foxtail competition was highly variable from one date of seeding to the next, but there was no correlation between the level of green foxtail competition and the date of seeding. Soil temperature and moisture at the time of seeding and early growth are thought to affect green foxtail competition in wheat critically.

Crop Losses in Wheat (Triticum aestivum) as Determined Using Weeded and Nonweeded Quadrats

Weed Science ◽  
1985 ◽  
Vol 33 (5) ◽  
pp. 734-740 ◽  
Author(s):  
Larry Hume
Keyword(s):  
Triticum Aestivum ◽  
Multiple Regression ◽  
Dry Weight ◽  
Accurate Method ◽  
Crop Loss ◽  
Crop Losses ◽  
Grain Crops ◽  
Crop Density ◽  
The Relationship ◽  
Crop Competition

The importance of including crop density in studies of weed-wheat competition and in making estimates of crop losses due to weeds was demonstrated. Wheat density in adjacent quadrats of 1 m2varied by an average of 25 plants in the farm fields and research plots examined. Differences between adjacent quadrats were in the same range for fields sown with different implements. Yield per plant, dry weight per plant, and tillering per plant decreased with increasing wheat density. For weed-crop competition studies in small-grain crops, the yields of weed-free and weedy quadrats are normally compared to estimate crop loss caused by competition. It was demonstrated that such estimates can be highly distorted if crop density is not taken into account. Current procedures used widely in agronomic competition studies are inadequate to properly define the relationship between crops and weeds. A more accurate method for performing such investigations is described in which both weed and crop abundance are determined. These variables are related to crop loss using multiple regression.

Effects of Soil pH on Competitive Ability and Leaf Nutrient Content of Corn (Zea maysL.) and Three Weed Species

Weed Science ◽  
1985 ◽  
Vol 33 (4) ◽  
pp. 447-451 ◽  
Author(s):  
Susan E. Weaver ◽  
Allan S. Hamill
Keyword(s):  
Soil Ph ◽  
Competitive Ability ◽  
Leaf Tissue ◽  
Dry Weight ◽  
Nutrient Content ◽  
Setaria Viridis ◽  
Weed Species ◽  
Field Corn ◽  
Green Foxtail ◽  
Companion Plant

Effects of soil pH on growth, competitive ability, and leaf nutrient content of corn (Zea maysL.), Powell amaranth (Amaranthus powelliiS. Wats. ♯ AMAPO), velvetleaf (Abutilon theophrastiMedic. ♯ ABUTH), and green foxtail [Setaria viridis(L.) Beauv. ♯ SETVI] were measured in the field. Corn yields were significantly reduced by weed competition at all pH levels, but leaf nutrient content, as a percentage of dry weight, was not affected. Aboveground dry weights of Powell amaranth and velvetleaf were significantly lower at pH 4.8 than at pH 6.0 or 7.3, whereas growth of green foxtail was greater at pH 4.8 than at pH 7.3. Weed competitive ability, as evidenced by reductions in dry weight, varied with soil pH and companion plant. Powell amaranth and velvetleaf had higher levels of S, Zn, and especially Mn, at pH 4.8 than at pH 7.3. N and K in the leaf tissue were greater in the weed species than in corn at all soil pH levels. The dicot species had higher percentages of Ca and Mg in leaf tissue at all soil pH levels and accumulated higher percentages of Mn at low pH than the monocot species.

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.

Growth Responses of Green and Yellow Foxtail (Setaria viridisand S.lutescens) to Shade

Weed Science ◽  
1984 ◽  
Vol 32 (6) ◽  
pp. 774-780 ◽  
Author(s):  
Carol J. Bubar ◽  
Ian N. Morrison
Keyword(s):  
Dry Matter ◽  
Field Experiments ◽  
Dry Weight ◽  
Tiller Number ◽  
The Other ◽  
Dry Matter Accumulation ◽  
Setaria Viridis ◽  
Growth Responses ◽  
Full Sunlight ◽  
Green Foxtail

The growth of green foxtail (Setaria viridisL. Beauv. ♯3SETVI) and yellow foxtail [S. lutescens(Weigel.) Hubb. ♯ SETLU] in full sunlight, under 55 and 73% shade and within a wheat (Triticum aestivumL. ‘Neepawa’) stand, was compared in field experiments conducted over 3 yr. Shade resulted in a proportionately greater reduction in tiller number of yellow foxtail than of green foxtail. Plants growing in full sunlight produced up to five times more tillers than those growing in the crop. Averaged over the 3 yr, the two shade treatments reduced dry-matter accumulation of both species by 40% or more. The dry weight of plants within the crop was only about one-eighth of that of plants grown in full sunlight. Under both shade treatments and in the crop, yellow foxtail was consistently taller than green foxtail. Nevertheless, no differences in dry weight occurred between species under either shade treatment or in the crop. The results indicate that neither of the two species is distinctly more shade tolerant than the other, nor better adapted to compete with wheat.

Effect of imazamethabenz on green foxtail, tartary buckwheat and wild oat at different growth stages

1991 ◽  
Vol 71 (3) ◽  
pp. 821-829 ◽  
Author(s):  
K. N. Harker ◽  
P. A. O'Sullivan
Keyword(s):  
Growth Stage ◽  
Field Experiments ◽  
Avena Fatua ◽  
Tartary Buckwheat ◽  
Growth Stages ◽  
Research Station ◽  
Regression Equations ◽  
Wild Oat ◽  
Setaria Viridis ◽  
Green Foxtail

Field experiments were conducted at the Lacombe Research Station to determine the influence of growth stage on the control of wild oat (Avena fatua L.) and Tartary buckwheat (Fagopyrum tartaricum (L.) Gaertn.) with imazamethabenz in wheat (Triticum aestivum L.). In greenhouse experiments, the effct of imazamethabenz on canola (Brassica campestris L.) or green foxtail (Setaria viridis L. Beauv.) at two growth stages was also studied. Canola and wild oat were highly susceptible, Tartary buckwheat was somewhat less susceptible, and green foxtail was rather tolerant to imazamethabenz. Imazamethabenz was much more effective on early growth stages of wild oat (2 leaf) and Tartary buckwheat (1–2 leaf), whereas the control of canola and the suppression of green foxtail was much less dependent on growth stage. Linear regression equations were developed to describe the response of the above species to the imazamethabenz treatments. Key words: AC 222, 293; phenology; regression; Setaria viridis; Fagopyrum tartaricum; Avena fatua

Influence of Nitrogen Fertility on Growth of Foxtail(Setaria)Taxa

Weed Science ◽  
1978 ◽  
Vol 26 (6) ◽  
pp. 547-550 ◽  
Author(s):  
M. M. Schreiber ◽  
P. L. Orwick
Keyword(s):  
Dry Weight ◽  
The Other ◽  
Nitrogen Level ◽  
Root Mass ◽  
Setaria Viridis ◽  
Nitrogen Levels ◽  
Giant Foxtail ◽  
Green Foxtail ◽  
Nitrogen Fertility ◽  
Low Nitrogen

Yellow foxtail [Setaria glauca(L.) Beauv.], giant foxtail(Setaria faberiHerrm.), giant green foxtail [Setaria viridisvar.major(Gaud.) Posp.], robust white foxtail(Setaria viridisvar.robusta-albaSchreiber), and robust purple foxtail(Setaria viridisvar.robusta-purpurea Schreiber)were grown from seed in pure stands in sand-soil nutrient solution cultures at various nitrogen levels. Within taxa dry weight of herbage differed significantly with nitrogen level, but dry weight of roots did not. Yellow foxtail produced more leaf area than the other four taxa regardless of nitrogen level. At the low nitrogen level, yellow foxtail produced significantly more root mass (dry weight) than the other taxa; giant foxtail was second in root-mass production. The order of root-mass production was the same at medium and high nitrogen levels, but only at a 12-h photoperiod. At a 16-h photoperiod, root production was equal in yellow foxtail and giant foxtail and was significantly greater in these taxa than in giant green foxtail, robust white foxtail, or robust purple foxtail. Generally similar relationships were evident in the root: shoot ratios. The chances for survival with giant foxtail taxa should be better for yellow foxtail than for the other foxtail taxa since yellow foxtail produced more root mass even at low nitrogen fertility, a condition common in undistrubed sites such as roadsides and fencerows.

Environment Influences Green Foxtail (Setaria viridis) Competition with Wheat (Triticum aestivum)

1992 ◽  
Vol 6 (3) ◽  
pp. 607-610 ◽  
Author(s):  
Dallas E. Peterson ◽  
John D. Nalewaja
Keyword(s):  
Triticum Aestivum ◽  
Soil Moisture ◽  
Spring Wheat ◽  
Nutrient Concentration ◽  
Moisture Stress ◽  
Setaria Viridis ◽  
Fresh Weight ◽  
Wheat Growth ◽  
Green Foxtail ◽  
Controlled Environments

Temperature, soil moisture, green foxtail density, relative emergence dates, and soil fertility effects on green foxtail and spring wheat competition were evaluated in controlled environments. Green foxtail competition was highest at 30 C and without moisture stress. Early green foxtail emergence increased competition with wheat more than changes in temperature, soil moisture, or green foxtail density. At 30 C, wheat fresh weight was reduced 50% by green foxtail seeded 4 d before wheat, but only 13% by foxtail seeded 4 d after wheat. Doubling the nitrogen and total nutrient concentration did not increase wheat growth, but increased foxtail weight 41 and 75%, respectively.

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