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

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

A COMPARISON OF MCP AND 2,4-D FOR THE CONTROL OF ANNUAL WEEDS IN GRAIN CROPS

1957 ◽  
Vol 37 (1) ◽  
pp. 69-83 ◽  
Author(s):  
H. A. Friesen ◽  
D. R. Walker
Keyword(s):  
Chenopodium Album ◽  
Amaranthus Retroflexus ◽  
Seedling Stage ◽  
Dichlorophenoxyacetic Acid ◽  
Growth Stages ◽  
Thlaspi Arvense ◽  
Wild Mustard ◽  
The Difference ◽  
Lamb’S Quarters ◽  
2,4 Dichlorophenoxyacetic Acid

Oats, flax and barley were sprayed with various formulations of MCP (2-methyl-4-chlorophenoxyacetic acid) and 2,4-D (2,4-dichlorophenoxyacetic acid) at a number of Experimental Farms in Western Canada in 1954 and 1955. Each formulation was applied at 4 and 8 ounces of acid equivalent per acre at each of two dates, viz., Date 1, when the weeds were in the seedling stage less than 3 inches in height; and Date 2, at a stage coinciding with the first appearance of buds on the major weed species.Stinkweed (Thlaspi arvense, L.), wild mustard (Brassica kaber (DC.) L.C. Wheeler var. pinnatifida (Stokes) L.C. Wheeler), lamb's quarters (Chenopodium album L.), Russian pigweed (Axyris amarantoides L.), and ball mustard (Neslia paniculata L.), were effectively controlled by each of the MCP and 2,4-D formulations used. Russian thistle (Salsola kali L.), and red-root pigweed (Amaranthus retroflexus L.), were not satisfactorily controlled by MCP, whereas hemp nettle (Galeopsis tetrahit L.) was not controlled by 2,4-D. Wild buckwheat (Polygonum convolvulus L.) was not controlled by any of the treatments. Each treatment was more effective when applied during the seedling stage of the weeds.On the basis of wood control and yield of grain the results of this study favour the use of MCP over 2,4-D with either oats or flax. Oats was significantly more tolerant to MCP, particularly if treated during the early growth stages when weed competition was most critical. With flax, the difference in tolerance was most pronounced in favour of MCP at the later date of treatment. The 2,4-D ester and low volatile ester resulted in a preponderance of plant deformities, lowered the yields of both oats and flax and delayed the maturity of flax significantly. Barley yields in this study were not adversely affected by any of the treatments.

scholarly journals AMINO ACID AND PROXIMATE ANALYSES OF WEED SEEDS

1977 ◽  
Vol 57 (1) ◽  
pp. 243-249 ◽  
Author(s):  
RUSSELL TKACHUK ◽  
V. JEAN MELLISH
Keyword(s):  
Amino Acid ◽  
Chenopodium Album ◽  
Essential Amino Acids ◽  
Amaranthus Retroflexus ◽  
Thlaspi Arvense ◽  
Wild Mustard ◽  
Acid Protein ◽  
Weed Seeds ◽  
Lamb’S Quarters ◽  
Amino Acid Balance

Weed seeds commonly found in Western Canadian cereals and oil seeds as dockage were examined for their amino acid, protein, oil and fiber contents. The weeds analyzed were Sinapis arvenis L.(wild mustard), Thlaspi arvense L. (stinkweed), Descurainia sophia (L.) Webb (flixweed), Polygonum convolvulus L. (wild buckwheat), Rumex pseudonatronatus L. (field dock), Avena fatua L. (wild oats), Setaria viridis (L.) Beauv. (green foxtail), Iva xanthifolia Nutt. (false ragweed), Chenopodium album L. (lamb’s-quarters), and Amaranthus retroflexus L. (redroot pigweed). Composite analysis showed that some of the weed seeds are high in protein and oil content. Amino acid analysis showed that many weeds have an excellent essential amino acid balance, and also a higher content of essential amino acids than do the commonly grown cereals. These results suggest that some weed seeds could be excellent sources of protein and oil for feed or food purposes.

Eliminating soil disturbance reduces post-alfalfa summer annual weed populations

2001 ◽  
Vol 81 (4) ◽  
pp. 881-884 ◽  
Author(s):  
P. D. Ominski ◽  
M. H. Entz
Keyword(s):  
Cropping Systems ◽  
Chenopodium Album ◽  
Soil Disturbance ◽  
Amaranthus Retroflexus ◽  
Weed Ecology ◽  
Wild Mustard ◽  
No Till ◽  
Lamb’S Quarters ◽  
Time Of Year ◽  
Brassica Kaber

The influence of method (tillage vs. no-till) and time of year of alfalfa (Medicago sativa L.) termination on the population of naturally occurring weeds was assessed over three site-years in southern Manitoba. Termination method was found to be more important than timing. Populations of weeds such as green foxtail [Setaria viridis (L.) Beauv.], redroot pigweed (Amaranthus retroflexus L.), wild mustard [Brassica kaber (DC) L.C. Wheeler] and lamb’s quarters (Chenopodium album L.) were usually lower (P < 0.05) in the undisturbed (i.e., no-till) system, compared to where tillage was used. It was concluded that the combination of alfalfa in rotation and no-till management can provide significant weed control benefits to cropping systems. Key words: Weed ecology, no-till cropping, forages

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

Effect of Additives upon Phenmedipham for Weed Control in Sugarbeets

Weed Science ◽  
1973 ◽  
Vol 21 (1) ◽  
pp. 67-70 ◽  
Author(s):  
Stephen D. Miller ◽  
John D. Nalewaja
Keyword(s):  
Weed Control ◽  
Linseed Oil ◽  
Chenopodium Album ◽  
Amaranthus Retroflexus ◽  
Herbicidal Activity ◽  
Redroot Pigweed ◽  
Wild Mustard ◽  
Green Foxtail ◽  
Helianthus Annus ◽  
Brassica Kaber

Weed control and sugarbeet (Beta vulgarisL.) injury from applications of methylm-hydroxycarbanilatem-methyl-carbanilate (phenmedipham) were influenced by additives, volume of additive, and species in both field and greenhouse experiments. Oils were more effective than the surfactant as additives to phenmedipham on green foxtail (Setaria virdis(L.) Beauv.), yellow foxtail (Setaria glauca(L.) Beauv.), redroot pigweed (Amaranthus retroflexusL.), or common lambsquarters (Chenopodium albumL.). Herbicidal activity of phenmedipham on kochia (Kochia scoparia(L.) Schrad.) or wild mustard (Brassica kaber(D.C.) L.C. Wheeler var.pinnatifida(Stokes) L.C. Wheeler) was not enhanced by any additive. Linseed oil (2.34 L/ha) enhanced the herbicidal activity of phenmedipham on green foxtail, yellow foxtail, and redroot pigweed more than petroleum (2.34 L/ha) or sunflower (Helianthus annusL.) oil (2.34 or 9.35 L/ha). However, linseed oil reduced the herbicidal activity of phenmedipham on kochia.

RE-EVALUATION OF TCA FOR GREEN FOXTAIL CONTROL IN RELATION TO SEED YIELD AND OIL QUALITY OF FLAX

1977 ◽  
Vol 57 (3) ◽  
pp. 969-976
Author(s):  
P. N. P. CHOW ◽  
D. G. DORRELL
Keyword(s):  
Seed Yield ◽  
Chenopodium Album ◽  
Oil Quality ◽  
Good Control ◽  
Amaranthus Retroflexus ◽  
Oil Composition ◽  
Linum Usitatissimum L ◽  
Green Foxtail ◽  
Increase Protein Content ◽  
Lamb’S Quarters

The role of TCA (trichloroacetic acid) in green foxtail (Setaria viridis (L.) Beauv.) control and its effect on seed yield and oil composition of flax (Linum usitatissimum L.) cvs. Noralta, Raja, and Redwood were re-assessed under various weedy conditions from 1972 to 1975. When a mixture of weeds was present, TCA at 2.24 kg/ha controlled green foxtail but failed to control lamb’s-quarters (Chenopodium album L.) and redroot pigweed (Amaranthus retroflexus L.). However, TCA mixtures which included one or two broad-leaf herbicides gave good control of all weeds and a 40% increase in yield over the untreated check. Under natural infestation conditions where green foxtail was light but the predominant weed, TCA at 2.24–4.48 kg/ha gave partial weed control but did not increase the seed yield of flax. Cultivation consistently produced the highest yields and TCA alone generally produced the lowest yields. While the lower yields experienced with TCA were partially offset by cultivating before or after the application of TCA, in no cases were the yields from these combined treatments ever equal to that of cultivation alone. Plants treated with 3.36 and 4.48 kg/ha of TCA in the greenhouse showed leaf injury and a significant reduction in top weight. It is suggested that this type of injury is one of the factors contributing to the failure of TCA to significantly increase the yield of flax following suppression of green foxtail growth. TCA tended to increase protein content but has little effect on oil content, fatty acid composition, or iodine number.

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

Influence of Rainfall on the Phytotoxicity of Foliarly Applied 2,4-D

Weed Science ◽  
1981 ◽  
Vol 29 (3) ◽  
pp. 349-355 ◽  
Author(s):  
Richard Behrens ◽  
M. A. Elakkad
Keyword(s):  
Chenopodium Album ◽  
Field Studies ◽  
Amaranthus Retroflexus ◽  
Time Interval ◽  
Simulated Rainfall ◽  
Response Level ◽  
Common Lambsquarters ◽  
Wild Mustard ◽  
Dichlorophenoxy Acetic Acid ◽  
Brassica Kaber

To study rainfall effects, simulated rainfall was applied to velvetleaf (Abutilon theophrastiMedic.), common lambsquarters (Chenopodium albumL.), wild mustard [Brassica kaber(DC.) L. C. Wheeler var.pinnatifida(Stokes) L. C. Wheeler], soybean [Glycine max(L.) Merr. ‘Hodgson’], and redroot pigweed (Amaranthus retroflexusL.) in greenhouse and field studies following foliar applications of the alkanolamine (AKA) salt or the butoxyethanol (BE) ester of 2,4-D [(2,4-dichlorophenoxy)acetic acid] at rates that induced equivalent levels of phytotoxicity. Simulated rainfall less than 1 min after herbicide treatment reduced the phytotoxicity of the AKA salt of 2,4-D to a much greater extent than that of the BE ester with effects ranging from elimination of all injury from the AKA salt to soybeans to no reduction in phytotoxicity of the BE ester to common lambsquarters. The quantity of simulated rainfall required to induce maximum reductions in phytotoxicity of the BE ester ranged from 1 mm on common lambsquarters to 15 mm on velvetleaf. The time interval from 2,4-D treatment until rainfall required to achieve a phytotoxic response level of 80% of that attained without rainfall varied greatly among plant species and herbicide formulations; ranging from less than 1 min for the BE ester on common lambsquarters to more than 24 h for the AKA salt on velvetleaf. The addition of an alkylarylpolyoxyethylene glycol surfactant to 2,4-D spray solutions reduced herbicide rates required to induce equivalent levels of phytotoxicity, increased losses in phytotoxicity of the BE ester caused by rainfall, and reduced the time interval from treatment to rainfall required to attain an equivalent level of phytotoxicity with the AKA salt.

Rhythmic Leaf Movements of Some Common Weeds

Weed Science ◽  
1979 ◽  
Vol 27 (4) ◽  
pp. 401-415 ◽  
Author(s):  
Robert N. Andersen ◽  
Willard L. Koukkari
Keyword(s):  
Chenopodium Album ◽  
Continuous Light ◽  
Datura Stramonium ◽  
Amaranthus Retroflexus ◽  
Rhythmic Pattern ◽  
Weed Species ◽  
Rhythmic Movements ◽  
Wild Mustard ◽  
Dark Regime ◽  
Leaf Movements

In growth chamber studies, we measured the movement of cotyledons and leaves or leaflets in seedlings of nine weed species to determine: the magnitude of movement, whether movements followed a rhythmic pattern, and if rhythmic movements were endogenously controlled. Seedlings were always entrained under a 15-h light:9-h dark regime. Measurements were made at 3-h intervals for 3 to 4 days under four light regimes: alternating 15-h light:9-h dark; continuous light; one 15-h light:9-h dark span, followed by continuous light; and a 15-h light:9-h dark regime, in which the dark span was advanced 9 h (phase shift) when measurements were begun. No clearly defined pattern of leaf movement was found in wild mustard [Brassica kaber(DC.) L. C. Wheeler var.pinnatifida(Stokes) L. C. Wheeler]. Daily rhythmic leaf movements that did not appear to be endogenously controlled were found in redroot pigweed (Amaranthus retroflexusL.) and black nightshade (Solanum nigrumL.). Circadian rhythmic leaf movements that appeared to be under endogenous control were found in jimson-weed (Datura stramoniumL.), common lambsquarters (Chenopodium albumL.), common cocklebur (Xanthium pensylvanicumWallr.), prickly sida (Sida spinosaL.), sicklepod (Cassia obtusifoliaL.), and coffee senna (Cassia occidentalisL.).

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