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

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

scholarly journals Differential susceptibility of agricultural weeds to ultraviolet-B radiation

2002 ◽  
Vol 82 (4) ◽  
pp. 789-796 ◽  
Author(s):  
N. H. Furness ◽  
M. K. Upadhyaya
Keyword(s):  
Leaf Area ◽  
Chenopodium Album ◽  
Amaranthus Retroflexus ◽  
Ultraviolet B ◽  
Setaria Viridis ◽  
Stellaria Media ◽  
Redroot Pigweed ◽  
Green Foxtail ◽  
Lamb’S Quarters ◽  
Polygonum Persicaria

Differential morphological sensitivity of weed species to ultraviolet-B (UV-B) radiation (290–320 nm) may alter competitive relationships among weeds and associated crop species as the level of this radiation changes. In order to determine relative sensitivity of common chickweed [Stellaria media (L.) Vill.], green foxtail (Setaria viridis L.), lady's-thumb (Polygonum persicaria L.), lamb's-quarters (Chenopodium album L.), redroot pigweed (Amaranthus retroflexus L.), and shepherd's-purse (Capsella bursa-pastoris L.) to this radiation, seedlings were grown under 0, 7, and 11 kJ m-2 d-1 of biologically effective UV-B radiation in a greenhouse for 6 wk. The influence of UV-B radiation on seedling growth and morphology was investigated. UV-B radiation reduced shoot height in green foxtail (by up to 41%), lamb's-quarters, and redroot pigweed, and increased tillering in green foxtail seedlings. Leaf area and leaf biomass in common chickweed, green foxtail, lamb's-quarters, and shepherd's-purse, and stalk biomass in common chickweed, green foxtail, lamb's-quarters, redroot pigweed and shepherd's-purse declined in response to UV-B radiation. In common chickweed, leaf area was reduced by 74% at 11 kJ m-2 d-1. Root biomass was reduced by UV-B radiation in all species (up to 68% at 11 kJ m-2 d-1 in common chickweed) except lady's-thumb. Specific leaf weight increased and leaf area ratio declined in response to UV-B radiation in common chickweed and shepherd's-purse. Exposure to UV-B radiation increased the leaf weight ratio in common chickweed. Shoot:root ratios increased in response to UV-B radiation in common chickweed and redroot pigweed. Scanning electron microscopy revealed collapsed epidermal cells in occasional necrotic regions on adaxial leaf surfaces of redroot pigweed grown under 11 kJ m-2 d-1 UV-B radiation. Morphology and growth of lady's-thumb were not affected by UV-B radiation. This study suggests that common agricultural weeds have differential morphological and growth responses to UV-B-enhanced environments. Sensitivity to UV-B radiation was greatest for common chickweed and least for lady's-thumb and redroot pigweed. Key words: ultraviolet-B, Amaranthus retroflexus, Capsella bursa-pastoris, Chenopodium album, Polygonum persicaria, Setaria viridis, Stellaria media

scholarly journals The Effect of Different Soil Tillage Systems and Crop Residues on the Composition of Weed Communities

Agronomy ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1276
Author(s):  
Vaida Steponavičienė ◽  
Aušra Marcinkevičienė ◽  
Lina Marija Butkevičienė ◽  
Lina Skinulienė ◽  
Vaclovas Bogužas
Keyword(s):  
Soil Ph ◽  
Crop Residues ◽  
Soil Tillage ◽  
Reduced Tillage ◽  
Plant Residues ◽  
No Tillage ◽  
Agricultural Crops ◽  
Weed Species ◽  
Tillage Systems ◽  
Weed Communities

The composition of weed communities in agricultural crops is dependent on soil properties and the applied agronomic practices. The current study determined the effect of different tillage systems and crop residue on the soil weed community composition. The research programme encompassed 2013–2015 in a long-term field experiment located in the Experimental Station of Vytautas Magnus University in Lithuania. The soil type in the experimental field was qualified as Endocalcaric Stagnosol (Aric, Drainic, Ruptic, Amphisiltic). Weeds were categorised into communities according to soil pH, nitrogen and moisture indicators. The results of investigations were grouped using cluster analysis. Agricultural crops were dominated by different weed species depending on the soil pH and moisture. Weed species were relatively more frequent indicating nitrogen-rich and very nitrogen-rich soils. In the reduced tillage and no-tillage systems, an increase in the abundance of weed species indicating moderate acidity and low acidity, moderately wet and wet, nitrogen-rich and very nitrogen-rich soils was observed. The application of plant residues decreased the weed species abundance. In the reduced tillage and no-tillage systems, the quantitative distribution of weed was often uneven. By evaluating the association of weed communities with groups of different tillage systems with or without plant residues, their control can be optimised.

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

The Fate of Nitrofen in Rape, Redroot Pigweed, and Green Foxtail

Weed Science ◽  
1971 ◽  
Vol 19 (5) ◽  
pp. 555-558 ◽  
Author(s):  
D. Hawton ◽  
E. H. Stobbe
Keyword(s):  
Light Intensity ◽  
Brassica Campestris ◽  
Molecular Size ◽  
Amaranthus Retroflexus ◽  
High Light ◽  
Setaria Viridis ◽  
Light Conditions ◽  
Ether Linkage ◽  
Redroot Pigweed ◽  
Green Foxtail

The fate of 2,4-dichlorophenyl p-nitrophenyl ether (nitrofen) in the foliage of rape (Brassica campestris L. ‘Echo’), redroot pigweed (Amaranthus retroflexus L.), and green foxtail (Setaria viridis (L.) Beauv.) was investigated with the aid of 14C-nitrofen. Only limited amounts of the label were translocated in these species. Plants treated with 14C-nitrofen under high light conditions produced several labelled compounds of different molecular size and chromatographic properties. The time at which these compounds were first detectable depended on light intensity. At least two of these compounds are lipid-nitrofen conjugates or nitrofen polymers and others may be formed by cleavage of nitrofen at the ether linkage.

Low-Rate Applications of Herbicides in Conventional and Reduced Tillage Potatoes (Solanum tuberosum)

1990 ◽  
Vol 4 (3) ◽  
pp. 509-513 ◽  
Author(s):  
Russell W. Wallace ◽  
Robin R. Bellinder
Keyword(s):  
Solanum Tuberosum ◽  
Weed Control ◽  
Production Systems ◽  
Potato Production ◽  
Reduced Tillage ◽  
Tillage Systems ◽  
Common Lambsquarters ◽  
Redroot Pigweed ◽  
Significant Yield ◽  
Low Rate

Linuron, metribuzin, oryzalin, and metolachlor were applied at recommended (1X) and two-thirds (0.67X) rates to evaluate control of redroot pigweed and common lambsquarters in conventional and rye-stubble reduced-tillage potato production systems. Regardless of tillage, common lambsquarters control was satisfactory during both seasons at both rates of linuron, metribuzin, and oryzalin. Redroot pigweed control by these three herbicides, although excellent in 1988, was poor in RT plots during 1987. Yields did not differ between tillage systems. Reduced weed control with metolachlor during both seasons, and possible crop injury with linuron in 1987 resulted in significant yield reductions.

THE LONG-TERM EFFECTS OF FERTILIZER APPLICATION AND THREE ROTATIONS ON WEED COMMUNITIES IN WHEAT (AFTER 21–22 YEARS AT INDIAN HEAD, SASKATCHEWAN)

1982 ◽  
Vol 62 (3) ◽  
pp. 741-750 ◽  
Author(s):  
LARRY HUME
Keyword(s):  
Species Composition ◽  
Fertilizer Application ◽  
Continuous Cropping ◽  
Long Term Effects ◽  
Canada Thistle ◽  
Short Term ◽  
Weed Communities ◽  
Green Foxtail ◽  
Lamb’S Quarters

The effect of fertilizer application and three rotations (continuous cropping, fallow-wheat, and fallow-wheat-wheat rotations) on the species composition of the weed community was examined using rotations that had been running for 21–22 yr at Indian Head, Saskatchewan. Before spring seeding, stinkweed and lamb’s-quarters were more abundant on wheat after fallow than they were on either wheat following wheat after fallow or on continuous cropping. After seeding, continuous cropping produced the largest weed densities of green foxtail, thyme-leaved spurge, and vetch. In most instances, Canada thistle was most abundant on continuously cropped and nonfertilized plots. After spring seeding, green foxtail was the only species with a larger density on fertilized plots. Interactions between fertilizer application and rotation, and among species, influenced species composition in the weed community. Fertilizer application tended to reduce community differences between continuous cropping and short-term wheat-fallow rotations. Allelopathic effects of Canada thistle may have reduced green foxtail and redroot pigweed densities. With the use of 2-or 3-yr wheat-fallow rotations and herbicide application, weed problems can be minimized in southeastern Saskatchewan.

Selectivity of Nitrofen among Rape, Redroot Pigweed, and Green Foxtail

Weed Science ◽  
1971 ◽  
Vol 19 (1) ◽  
pp. 42-44 ◽  
Author(s):  
D. Hawton ◽  
E. H. Stobbe
Keyword(s):  
Brassica Campestris ◽  
Amaranthus Retroflexus ◽  
Water Soluble ◽  
Setaria Viridis ◽  
Weed Species ◽  
Differential Effects ◽  
Redroot Pigweed ◽  
Green Foxtail

The selectivity of 2,4-dichlorophenylp-nitrophenyl ether (nitrofen) among rape (Brassica campestrisL., var. Echo) and two weed species, redroot pigweed (Amaranthus retroflexusL.) and green foxtail (Setaria viridis(L.) Beauv.), was determined quantitatively by a replicated dosage-response experiment. On an ED50basis, green foxtail and redroot pigweed were, respectively, 5.8 and 63.3 times more susceptible than rape. Selectivity was divided into three parameters; viz., differential spray retention, differential penetration, and differential effects within the plant. Differences in retention were measured with the use of a water-soluble dye, while differences in penetration were determined with14C-labelled nitrofen. Spray retention on green foxtail was 66% of that on the rape and 64% as much nitrofen penetrated redroot pigweed as penetrated rape. Under the conditions of these tests it was estimated that green foxtail and redroot pigweed were, respectively, 9 and 99 times more susceptible to nitrofen than was rape.

Physiological Bases of Sugarbeet (Beta vulgaris) Tolerance to Foliar Application of Ethofumesate

Weed Science ◽  
1981 ◽  
Vol 29 (6) ◽  
pp. 648-654 ◽  
Author(s):  
David N. Duncan ◽  
William F. Meggitt ◽  
Donald Penner
Keyword(s):  
Beta Vulgaris ◽  
Foliar Application ◽  
Amaranthus Retroflexus ◽  
Ambrosia Artemisiifolia ◽  
Water Soluble ◽  
Weed Species ◽  
Common Ragweed ◽  
Species Response ◽  
Redroot Pigweed ◽  
Photosynthesis And Respiration

Absorption, translocation, and metabolism of foliar-applied ethofumesate [(±)-2-ethoxy-2,3-dihydro-3,3-dimethyl-5-benzofuranyl methanesulphonate] were studied to explain field observations showing differences in susceptibility among sugarbeet (Beta vulgarisL.), common ragweed (Ambrosia artemisiifoliaL.), redroot pigweed (Amaranthus retroflexusL.), and common lambsquarters (Chenopodium albumL.). In laboratory studies, two- to four-leaf seedlings of the highly susceptible species, redroot pigweed and common lambsquarter, absorbed greater amounts of14C-ethofumesate from foliar application than the moderately susceptible common ragweed and tolerant sugarbeet. Sugarbeet translocated very little14C from treated foliage to untreated plant tissue. All weed species translocated14C-ethofumesate to untreated leaf tissue when14C-ethofumesate was applied to seedlings at the two-leaf stage. Ethofumesate was translocated basipetally to the stem and root of two-leaf redroot pigweed and common lambsquarter seedlings. A high percentage of the14C was found in the water-soluble fraction in sugarbeet seedlings, indicating inactivation. The amount of metabolites recovered in the non-polar fraction depended on the stage of plant growth. Total photosynthesis and respiration in redroot pigweed was inhibited 4 h after foliar application and did not recover after 96 h. Uptake and evolution of CO2were also inhibited in sugarbeet leaves, but they recovered rapidly, depending on age of plant at treatment. The stage of plant development was the key factor determining species response to foliar treatments of ethofumesate in terms of absorption, metabolism, and total photosynthesis and respiration.

Effect of Early Competition on Growth of Common Milkweed

Weed Science ◽  
1975 ◽  
Vol 23 (1) ◽  
pp. 1-3 ◽  
Author(s):  
L. L. Evetts ◽  
O. C. Burnside
Keyword(s):  
Sorghum Bicolor ◽  
Amaranthus Retroflexus ◽  
Setaria Viridis ◽  
Light Competition ◽  
Asclepias Syriaca ◽  
Redroot Pigweed ◽  
Light Soil ◽  
Green Foxtail ◽  
Shoot Weight ◽  
Annual Weeds

Four modes of competition were studied in relation to early development of common milkweed (Asclepias syriacaL.) alone and in competition with green foxtail [Setaria viridis(L.) Beauv], redroot pigweed (Amaranthus retroflexusL.), and sorghum [Sorghum bicolor(L.) Moench ‘RS-626’]. The three species were used to study the effect of no competition, light competition, soil competition, and light and soil (full) competition on common milkweed. Common milkweed height was significantly reduced by soil and full competition with the three species, while only green foxtail caused a significant reduction in height due to light competition. Shoot weight of common milkweed was significantly reduced by light, soil, and full competition by the three species. Reproduction percentage of common milkweed roots was most severely reduced by light and full competition from green foxtail and redroot pigweed. An environment conducive to the establishment of the perennial common milkweed from seed exists when annual weeds are removed by herbicides.

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