Comparison of weed communities in Manitoba ecoregions and crops

2000 ◽  
Vol 80 (4) ◽  
pp. 963-972 ◽  
Author(s):  
R. C. Van Acker ◽  
A. G. Thomas ◽  
J. Y. Leeson ◽  
S. Z. Knezevic ◽  
B. L. Frick
Keyword(s):  
Weed Management ◽  
Amaranthus Retroflexus ◽  
Weed Species ◽  
Canada Thistle ◽  
Wild Mustard ◽  
Polygonum Convolvulus ◽  
Weed Communities ◽  
Green Foxtail ◽  
Poaceae Family ◽  
Weed Survey

In 1997, a weed survey was conducted during July and August in fields of wheat, barley, oat, canola and flax in Manitoba. Field selection was based on a stratified-random sampling methodology using ecodistricts as strata. Species in the Poaceae family were most commonly observed in the survey, followed by species in the Polygonaceae, Asteraceae and Brassicaceae families. The six most abundant weed species were green foxtail [Setaria viridis (L.) Beauv.], wild oats (Avena fatua L.), wild buckwheat (Polygonum convolvulus L.), Canada thistle (Cirsium arvense L.), redroot pigweed (Amaranthus retroflexus L.) and wild mustard (Sinapis arvensis L.). The survey highlighted significant differences between ecoregions and between crops in residual weed infestations. The weed community in the Boreal Transition ecoregion was dominated by seven species, whereas fields in the Aspen Parkland and Lake Manitoba Plain ecoregions were dominated by two species and the Interlake Plain ecoregion was dominated by only one species. Although significant differences were found between the weed communities in crops, they were not as great as differences between ecoregions. The Manitoba residual weed community in 1997 was very similar to that reported for 1978–1981 and 1986, suggesting that the same species should remain a focus for weed management. Key words: Weed survey, weed relative abundance, weed distributions, Manitoba ecoregions

Tolpyralate Efficacy: Part 1. Biologically Effective Dose of Tolpyralate for Control of Annual Grass and Broadleaf Weeds in Corn

2018 ◽  
Vol 32 (6) ◽  
pp. 698-706 ◽  
Author(s):  
Brendan A. Metzger ◽  
Nader Soltani ◽  
Alan J. Raeder ◽  
David C. Hooker ◽  
Darren E. Robinson ◽  
...  
Keyword(s):  
Effective Dose ◽  
Weed Management ◽  
Field Studies ◽  
Biologically Effective Dose ◽  
Limited Information ◽  
Weed Species ◽  
Common Lambsquarters ◽  
Wild Mustard ◽  
Low Field ◽  
Green Foxtail

AbstractTolpyralate is a new 4-hydroxyphenyl-pyruvate dioxygenase (HPPD)-inhibiting herbicide for POST weed management in corn; however, there is limited information regarding its efficacy. Six field studies were conducted in Ontario, Canada, over 3 yr (2015 to 2017) to determine the biologically effective dose of tolpyralate for the control of eight annual weed species. Tolpyralate was applied POST at six doses from 3.75 to 120 g ai ha−1and tank mixed at a 1:33.3 ratio with atrazine at six doses from 125 to 4,000 g ha−1. Regression analysis was performed to determine the effective dose (ED) of tolpyralate, and tolpyralate+atrazine, required to achieve 50%, 80%, or 90% control of eight weed species at 1, 2, 4, and 8 wk after application (WAA). The ED of tolpyralate for 90% control (ED90) of velvetleaf, common lambsquarters, common ragweed, redroot pigweed or Powell amaranth, and green foxtail at 8 WAA was ≤15.5 g ha−1; however, tolpyralate alone did not provide 90% control of wild mustard, barnyardgrass, or ladysthumb at 8 WAA at any dose evaluated in this study. In contrast, the ED90for all species in this study with tolpyralate+atrazine was ≤13.1+436 g ha−1, indicating that tolpyralate+atrazine can be highly efficacious at low field doses.

A survey of the occurrence of seedling weeds in spring annual crops in Manitoba

1991 ◽  
Vol 71 (3) ◽  
pp. 811-820 ◽  
Author(s):  
A. G. Thomas ◽  
D. I. Donaghy
Keyword(s):  
Chenopodium Album ◽  
Abundant Species ◽  
Amaranthus Retroflexus ◽  
Canada Thistle ◽  
Perennial Weed ◽  
Wild Buckwheat ◽  
Annual Crops ◽  
Wild Oats ◽  
Wild Mustard ◽  
Green Foxtail

A floristic survey for weeds in spring annual crops throughout Manitoba from 1975 to 1978 indicated the occurrence of a total of 83 species in 654 fields. Field counts were done during June when the crop and weeds were in the seedling stage. In terms of total abundance, the 28 annual dicotyledonous weeds were found to be the most important group among the 50 species occurring in more than 1% of the fields. Wild buckwheat (Polygonum convolvulus L.), wild mustard (Sinapis arvensis L.), redroot pigweed (Amaranthus retroflexus L.), and lamb's-quarters (Chenopodium album L.) were the most widespread and abundant species in this group with mean densities from 9.6 to 16.2 plants m−2. The combined abundance of green foxtail (Setaria viridis L.), wild oats (Avena fatua L.), and barnyard grass (Echinochloa crusgalli (L.) Beauv.), the three major annual monocotyledonous weeds, was nearly equal to that of the annual dicotyledonous weed group. Green foxtail was the most abundant weed, occurring in 89% of the fields at mean densities of 270.5 plants m−2. Canada thistle (Cirsium arvense (L.) Scop.) and perennial sow-thistle (Sonchus arvensis L.) were the most abundant species in the biennial and perennial weed group and had mean densities of 4.4–4.8 plants m−2 in infested fields. Key words: Weed survey, green foxtail, wild oats, wild buckwheat, wild mustard, Canada thistle

Evaluating Seed Shatter of Economically Important Weed Species

Weed Science ◽  
2016 ◽  
Vol 64 (4) ◽  
pp. 673-682 ◽  
Author(s):  
Nikki R. Burton ◽  
Hugh J. Beckie ◽  
Christian J. Willenborg ◽  
Steven J. Shirtliffe ◽  
Jeff J. Schoenau ◽  
...  
Keyword(s):  
Weed Management ◽  
Field Experiments ◽  
Management Strategies ◽  
Wild Oat ◽  
Population Abundance ◽  
Weed Seed ◽  
Weed Species ◽  
Wild Mustard ◽  
Green Foxtail ◽  
Crop Maturity

The increasing occurrence of herbicide resistance, along with no new herbicide modes of action developed in over 30 yr, have increased the need for nonherbicidal weed management strategies and tactics. Harvest weed seed control (HWSC) practices have been successfully adopted in Australia to manage problematic weeds. For HWSC to be effective, a high proportion of weed seeds must be retained on the plant at crop maturity. This 2-yr (2014, 2015) study evaluated seed shatter of wild oat, green foxtail, wild mustard, and cleavers in both an early (field pea) and late (spring wheat) maturity crop in field experiments at Scott, Saskatchewan. Seed shatter was assessed using shatter trays collected once a week during crop ripening stage, as well as at two crop maturation or harvest stages (swathing, direct-combining). Seed shatter differed among weed species, but was similar between crops at maturity: ca. 30% for wild oat, 5% for cleavers, < 2% for wild mustard, and < 1% for green foxtail. Overall, seed shatter of wild oat occurred sooner and at greater levels during the growing season compared with the other weed species. Viability of both shattered and plant-retained seeds was relatively high for all species. The small amount of seed shatter of cleavers, wild mustard, and green foxtail suggests that these species may be suitable candidates for HWSC. Due to the amount and timing of wild oat seed shatter, HWSC may not reduce population abundance of this grassy weed.

Weed surveys in different tillage systems in southwestern Ontario field crops

1992 ◽  
Vol 72 (4) ◽  
pp. 1337-1347 ◽  
Author(s):  
B. Frick ◽  
A. G. Thomas
Keyword(s):  
Amaranthus Retroflexus ◽  
Ambrosia Artemisiifolia ◽  
Control Measures ◽  
Reduced Tillage ◽  
Tillage Systems ◽  
Redroot Pigweed ◽  
Weed Communities ◽  
Green Foxtail ◽  
Lamb’S Quarters ◽  
Weed Survey

A weed survey of 593 corn, soybean and winter wheat fields in southwestern Ontario was conducted during 1988 and 1989 to determine the abundance and distribution of weeds under a variety of tillage systems. The survey was conducted after all weed-control measures had been carried out. A total of 82 weed species and groups of species were recorded. Many weeds were found infrequently. The most abundant weeds were green foxtail (Setaria viridis (L.) Beauv.), lamb’s-quarters (Chenopodium album L.), quack grass (Agropyron repens (L.) Beauv.), redroot pigweed (Amaranthus retroflexus L.), common ragweed (Ambrosia artemisiifolia L.) and dandelion (Taraxacum officinale Weber). These weeds accounted for 54% of the total relative abundance. Weed communities in individual fields were highly variable. Most fields had fewer than 10 species, and nearly half of the fields had fewer than 6 weeds m−2. Six weeds, yellow foxtail (Setaria glauca (L.) Beauv.), quack grass, crab grass spp. (Digitaria spp.), lamb’s-quarters, green foxtail and chickweed (Stellaria media (L.) Vill.), occurred at densities greater than 100 plants or shoots m−2 in at least one field. Similar weed communities were found in fields that had different tillage histories. Annual weeds were found at higher densities and perennial weeds at lower densities in reduced tillage than in conventional tillage. Weeds were found at highest total densities in fields with no tillage. The six most abundant weeds in the current study were present in Ontario prior to the 1900s.Key words: Weed survey, reduced tillage, green foxtail, lamb’s-quarters, quack grass, redroot pigweed

scholarly journals Weeds distribution and abundance in irrigated fields of White Nile State

2015 ◽  
Vol 4 (4) ◽  
pp. 45-61
Author(s):  
Mohamed Elkhawad ◽  
Amna Abdalla ◽  
Abosofian Osman
Keyword(s):  
Weed Management ◽  
Field Survey ◽  
Management Strategies ◽  
Mean Field ◽  
Survey Method ◽  
Weed Species ◽  
Field Frequency ◽  
Weed Communities ◽  
White Nile ◽  
Weed Survey

Field survey was conducted during the summer season of 2011- 2012 to determine the weed flora and weed dominance at the irrigated sites of White Nile State. The State was divided into six irrigated sites from which a total of thirty- five fields were selected and ten quadrates (1m2) from each field were taken randomly. In each quadrate individual weed species were recorded. Field frequency, uniformity and mean field density were also determined for each weed. Fifty five weed species belonging to twenty- four families (three monocotyledonous and twenty- one dicotyledonous) were recorded. Brachiaria eruciformis, Brachiaria reptans, Thunbergia annua and Ipomoea cordofana were the most dominant weed species in most fields. The highest Abundance Index were recorded by Ipomoea cordofana at El Salam and El Dawium counties (208.16 and 116.35), Brachiaria eruciformis at Um Remta and El Gebalen counties (158.80 and 79.23), Brachiaria reptans at Kosti (116.54) and Momordica balsamina at Gezira Aba county (90.06). Brachiaria eruciformis showed the highest MFD and Uniformity at El Salam and Um Remta Counties (19.11 and 80.00), respectively, and highest frequency value was recorded by Ipomoea cordofana (142.86) at El Salam County. The AI which used as weed survey method is to evaluate the weed management strategies and the change of weed species in weed communities through years.International Journal of Environment Vol.4(4) 2015: 45-61

scholarly journals Optimization of foramsulfuron doses for post-emergence weed control in maize (Zea mays L.)

2016 ◽  
Vol 14 (3) ◽  
pp. e1005 ◽  
Author(s):  
Euro Pannacci
Keyword(s):  
Weed Control ◽  
Growth Stage ◽  
Amaranthus Retroflexus ◽  
Recommended Dose ◽  
Weed Species ◽  
Common Lambsquarters ◽  
Black Nightshade ◽  
Redroot Pigweed ◽  
Wild Mustard ◽  
Green Foxtail

Four field experiments were carried out from 2011 to 2014 in order to evaluate the effects of foramsulfuron, applied at the recommended (60.8 g a.i./ha) and reduced doses (1/3 and 2/3), on the efficacy against several of the most important weeds in maize. For each “year-weed” combination, dose-response curves were applied to estimate the dose of foramsulfuron required to obtain 90% and 95% weed control (ED90 and ED95). Foramsulfuron phytotoxicity on maize and crop yield were assessed. Foramsulfuron at 1/3 of the recommended dose (20.3 g a.i./ha) provided 95% efficacy against redroot pigweed (Amaranthus retroflexus L.), green foxtail (Setaria viridis (L.) Beauv.), wild mustard (Sinapis arvensis L.) and black nightshade (Solanum nigrum L.). Velvetleaf (Abutilon theophrasti Medik.), common lambsquarters (Chenopodium album L.) and barnyardgrass (Echinochloa crus-galli (L.) Beauv.) were satisfactorily controlled (95% weed efficacy) with ED95 ranged from 20 to 50 g/ha of foramsulfuron (about from 1/3 to 5/6 of the recommended dose) depending on growth stage. The recommended dose was effective against pale smartweed (Polygonum lapathifolium L.) at 2-4 true leaves (12-14 BBCH scale), but this dose did not kill plants larger than 2-4 true leaves. The ranking among weed species based on their susceptibility to foramsulfuron was: redroot pigweed = green foxtail = wild mustard = black nightshade > velvetleaf = common lambsquarters = barnyardgrass > pale smartweed. Dose of foramsulfuron can be reduced below recommended dose depending on weed species and growth stage. Foramsulfuron showed a good crop selectivity and had no negative effect on maize yield.

A WEED SURVEY OF PEDIGREED ALFALFA SEED FIELDS IN MANITOBA

1986 ◽  
Vol 66 (2) ◽  
pp. 413-416 ◽  
Author(s):  
M. S. GOODWIN ◽  
I. N. MORRISON ◽  
A. G. THOMAS
Keyword(s):  
Mean Field ◽  
Abundant Species ◽  
Canada Thistle ◽  
Field Density ◽  
Wild Mustard ◽  
Polygonum Convolvulus ◽  
Alfalfa Seed ◽  
Crepis Tectorum ◽  
Sonchus Arvensis ◽  
Weed Survey

Weeds were counted in 77 pedigreed alfalfa (Medicago sativa L.) seed fields located throughout Manitoba. The five most abundant species were all perennials: quackgrass (Agropyron repens (L.) Beauv.), dandelion (Taraxacum officinale Weber), Canada thistle (Cirsium arvense (L.) Scop.), bluegrass (Poa spp.), and perennial sow-thistle (Sonchus arvensis L.). Quackgrass occurred in 65% of the fields with a mean field density of 23.4 culms m−2, the highest density of any of the species. The next four most abundant species were annuals with narrow-leaved hawk’s-beard (Crepis tectorum L.) having the highest mean field density for annual species at 2.9 plants m−2, although it occurred less frequently (30%) than the other three annuals, wild buckwheat (Polygonum convolvulus L.), wild mustard (Sinapsis arvensis L.) and wild oats (Avena fatua L.).Key words: Weed survey, alfalfa, quackgrass, narrow-leaved hawk’s-beard

Floristic composition and relative abundance of weeds in annual crops of Manitoba

1991 ◽  
Vol 71 (3) ◽  
pp. 831-839 ◽  
Author(s):  
A. G. Thomas
Keyword(s):  
Relative Abundance ◽  
Chenopodium Album ◽  
Floristic Composition ◽  
Sampling Procedure ◽  
Amaranthus Retroflexus ◽  
Wild Buckwheat ◽  
Wild Oats ◽  
Wild Mustard ◽  
Green Foxtail ◽  
Lamb’S Quarters

Annual surveys for weeds of fields seeded to spring wheat, barley, oats, flax, and canola in Manitoba were conducted during 1978, 1979, and 1981. Fields were surveyed during July and early August each year using a stratified random sampling procedure. Data for the crops and years were combined for analysis. The frequency, the area infested, and the density of the infestation were determined for each species. These three measures of the abundance of the weed were combined into a single synthetic value called relative abundance. Nine of the 152 species recorded by the surveyors accounted for 77% of the total relative abundance. Ranked in order by relative abundance, these species were green foxtail (Setaria viridis (L.) Beauv.), wild oats (Avena fatua L.), wild buckwheat (Polygonum convolvulus L.), annual smartweed (Polygonum spp.), Canada thistle (Cirsium arvense (L.) Scop.), lamb's-quarters (Chenopodium album L.), wild mustard (Sinapis arvensis L.), perennial sow-thistle (Sonchus arvensis L.), and redroot pigweed (Amaranthus retroflexus L.). Green foxtail was the predominant weed with an abundance value three times larger than wild oats or wild buckwheat. The pattern of dominance found in Manitoba fields was similar to results from comparable surveys in Saskatchewan and North Dakota. Key words: Relative abundance, weed survey, weed density, green foxtail, wild oats, wild buckwheat

Weed Survey System used in Saskatchewan for Cereal and Oilseed Crops

Weed Science ◽  
1985 ◽  
Vol 33 (1) ◽  
pp. 34-43 ◽  
Author(s):  
A. Gordon Thomas
Keyword(s):  
Growing Season ◽  
Agricultural Extension ◽  
Sampling Procedure ◽  
Distribution Maps ◽  
Agricultural Extension Service ◽  
Polygonum Convolvulus ◽  
Green Foxtail ◽  
Survey System ◽  
Weed Survey

A weed survey system methodology was developed and used annually for 4 yr in the province of Saskatchewan. Based on a stratified random sampling procedure, fields were selected in wheat (Triticum aestivumL.), barley (Hordeum vulgareL.), oat (Avena sativaL.), rye (Secale cerealeL.), rape (Brassica napusL.,Brassica campestrisL.), and flax (Linum usitatissimumL.) crops. The boundaries of the 43 agricultural extension districts in the province formed the strata. The provincial agricultural extension service provided staff to conduct the survey. Computer processing of the data enabled reports, containing summary tables and distribution maps, to be distributed to extension, research, and industry personnel within 3 months after completion of the field survey. The field surveys were conducted late in the growing season before harvest commenced; hence, the weed populations consisted of species that had been present during the early part of the growing season and may have contributed to yield losses. During the 4 yr of the survey, weeds were counted in 4423 fields. Of the 164 species recorded, 97 species occurred in more than three fields. Only 29 species were encountered frequently in the fields. Green foxtail [Setaria viridis(L.) Beauv. # SETVI), wild buckwheat (Polygonum convolvulusL. # POLCO), and wild oat (Avena fatuaL. # AVEFA) were the top three species based on a ranking system using a measure called relative abundance.

Tolpyralate Efficacy: Part 2. Comparison of Three Group 27 Herbicides Applied POST for Annual Grass and Broadleaf Weed Control in Corn

2018 ◽  
Vol 32 (6) ◽  
pp. 707-713 ◽  
Author(s):  
Brendan A. Metzger ◽  
Nader Soltani ◽  
Alan J. Raeder ◽  
David C. Hooker ◽  
Darren E. Robinson ◽  
...  
Keyword(s):  
Effective Dose ◽  
Weed Control ◽  
Biologically Effective Dose ◽  
Annual Grass ◽  
Weed Species ◽  
Common Ragweed ◽  
Common Lambsquarters ◽  
Wild Mustard ◽  
Percentage Points ◽  
Green Foxtail

AbstractTolpyralate is a new Group 27 pyrazolone herbicide that inhibits the 4-hydroxyphenyl-pyruvate dioxygenase enzyme. In a study of the biologically effective dose of tolpyralate from 2015 to 2017 in Ontario, Canada, tolpyralate exhibited efficacy on a broader range of species when co-applied with atrazine; however, there is limited published information on the efficacy of tolpyralate and tolpyralate+atrazine relative to mesotrione and topramezone, applied POST with atrazine at label rates, for control of annual grass and broadleaf weeds. In this study, tolpyralate applied alone at 30 g ai ha−1 provided >90% control of common lambsquarters, velvetleaf, common ragweed, Powell amaranth/redroot pigweed, and green foxtail at 8 weeks after application (WAA). Addition of atrazine was required to achieve >90% control of wild mustard, ladysthumb, and barnyardgrass at 8 WAA. Tolpyralate+atrazine (30+1,000 g ai ha−1) and topramezone+atrazine (12.5+500 g ai ha−1) provided similar control at 8 WAA of the eight weed species in this study; however, tolpyralate+atrazine provided >90% control of green foxtail by 1 WAA. Tolpyralate+atrazine provided 18, 68, and 67 percentage points better control of common ragweed, green foxtail, and barnyardgrass, respectively, than mesotrione+atrazine (100+280 g ai ha−1) at 8 WAA. Overall, tolpyralate+atrazine applied POST provided equivalent or improved control of annual grass and broadleaf weeds compared with mesotrione+atrazine and topramezone+atrazine.

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