Interference of Annual Weeds in Seedling Alfalfa (Medicago sativa)

Weed Science ◽  
1988 ◽  
Vol 36 (5) ◽  
pp. 583-588 ◽  
Author(s):  
Albert J. Fischer ◽  
Jean H. Dawson ◽  
Arnold P. Appleby
Keyword(s):  
Medicago Sativa ◽  
Bromus Tectorum ◽  
Early Spring ◽  
Amaranthus Retroflexus ◽  
Downy Brome ◽  
Weed Interference ◽  
Alfalfa Hay ◽  
Winter Annual ◽  
Annual Weeds

Barnyardgrass [Echinochloa crus-galli(L.) Beauv. #4ECHCG] and pigweeds (mixture ofAmaranthus retroflexusL. # AMARE andA. powelliiS. Wats. # AMAPO) seeded separately with alfalfa (Medicago sativaL.) in mid-August suppressed alfalfa severely before frost killed them in October and November. Some alfalfa was killed, and yield of alfalfa forage was reduced in each of three harvests the following year. These weeds did not harm alfalfa seeded in mid-September. Downy brome (Bromus tectorumL. # BROTE) and tumble mustard (Sisymbrium altissimumL. # SSYAL) suppressed alfalfa seeded in August and September. They reduced alfalfa stands and reduced yield of alfalfa forage in each of three harvests the following year. Alfalfa seeded August 27 and allowed to compete with a mixture of these species for various periods was injured most by weeds that emerged with the alfalfa and remained uncontrolled until forage harvest in May. These weeds did not reduce alfalfa yields if removed by 36 days after alfalfa emergence. Thereafter, yield decreased as the period of weed interference increased. Interference was most damaging in early spring, when growth of winter annual weeds was rapid and vigorous. Weeds seeded 65 or more days after alfalfa emergence did not reduce alfalfa yields but sometimes produced enough biomass to reduce the quality of the first-cutting alfalfa hay.

Weeds and Alfalfa Hay Quality

Weed Science ◽  
1973 ◽  
Vol 21 (5) ◽  
pp. 400-401 ◽  
Author(s):  
H. P. Cords
Keyword(s):  
Medicago Sativa ◽  
Protein Content ◽  
Direct Effect ◽  
Dormant Period ◽  
Alfalfa Hay ◽  
Winter Annual ◽  
Winter Annual Weeds ◽  
Annual Weeds

Established stands of alfalfa (Medicago sativa L. ‘Lahontan’) at six field locations were treated with soil-active herbicides during the dormant period for the control of winter annual weeds. Weeds and alfalfa were hand separated at the first harvest. This forage, which varied widely in weed content, was analyzed for protein. The percentage of protein correlated negatively with weed content in all cases. Analyses of covariance revealed that the direct effect of the herbicides on protein content was either small or absent and that the primary cause of the negative correlations was weed content.

Survival of downy brome (Bromus tectorum) seed in four environments

Weed Science ◽  
1997 ◽  
Vol 45 (2) ◽  
pp. 225-228 ◽  
Author(s):  
Gail A. Wicks
Keyword(s):  
Great Plains ◽  
Soil Surface ◽  
Winter Precipitation ◽  
Early Spring ◽  
Downy Brome ◽  
Smooth Brome ◽  
Winter Annual ◽  
Annual Weeds ◽  
Chemical Fallow ◽  
Germinable Seed

Downy brome is one of the most troublesome winter annual weeds in winter wheat-fallow rotations in the central Great Plains. A 3-yr seed burial study was initiated to determine how long downy brome seed remained germinable when placed on the soil surface or 2.5 cm deep at four different times in four environments. Only 1 to 7% of the downy brome seed survived after 1 yr on the soil surface in chemical fallow and stubble mulch when deposited in August, but survival varied in September, October, and November. In 1970, a year with low fall and winter precipitation, 36 to 46% of the seed placed on the soil surface of chemical fallow in September, October, and November survived, compared with 1 to 8% for stubble mulch tillage. Early spring tillage covered more seed with soil, and downy brome seed survival decreased. When fall and winter precipitation was normal, stubble mulch and chemical fallow had 1 to 20% germinable seed remaining. Induced dormancy existed in some years. More downy brome seed survived when placed on the soil surface of crested wheatgrass sod (14 to 50%) than on smooth brome sod (0 to 36%). No differences existed among environments when downy brome seed was buried 2.5 cm deep. Only 0.4% of downy brome seed buried 2.5 cm survived after 1 yr when averaged across all environments.

Fall and Spring Preplant Herbicide Applications Influence Spring Emergence of Glyphosate-Resistant Horseweed (Conyza canadensis)

2010 ◽  
Vol 24 (1) ◽  
pp. 11-19 ◽  
Author(s):  
Vince M. Davis ◽  
Greg R. Kruger ◽  
Bryan G. Young ◽  
William G. Johnson
Keyword(s):  
Early Spring ◽  
Late Spring ◽  
Conyza Canadensis ◽  
No Till ◽  
Early Fall ◽  
Winter Annual ◽  
Winter Annual Weeds ◽  
Annual Weeds ◽  
Spring Emergence ◽  
Residual Control

Horseweed (Conyza canadensis) is a common weed in no-till crop production systems. It is problematic because of the frequent occurrence of biotypes resistant to glyphosate and acetolactate synthase (ALS)-inhibiting herbicides and its ability to complete its life cycle as a winter or summer annual weed. Tactics to control horseweed while controlling other winter annual weeds routinely fail; herbicide application timing and spring emergence patterns of horseweed may be responsible. The objectives of this experiment were to (1) determine the influence of fall and spring herbicides with and without soil residual horseweed activity on spring-emerging glyphosate-resistant (GR) horseweed density and (2) evaluate the efficacy and persistence of saflufenacil on GR horseweed. Field studies were conducted in southern Indiana and Illinois from fall 2006 to summer 2007 and repeated in 2007 to 2008. Six preplant herbicide treatments were applied at four application timings: early fall, late fall, early spring, and late spring. Horseweed plants were counted every 2 wk following the first spring application until the first week of July. Horseweed almost exclusively emerged in the spring at both locations. Spring horseweed emergence was higher when 2,4-D + glyphosate was fall-applied and controlled other winter annual weeds. With fall-applied 2,4-D + glyphosate, over 90% of the peak horseweed density was observed before April 25. In contrast, only 25% of the peak horseweed density was observed in the untreated check by April 25. Starting from the initiation of horseweed emergence in late March, chlorimuron + tribenuron applied early fall or early spring, and spring-applied saflufenacil at 100 g ai/ha provided greater than 90% horseweed control for 12 wk. Early spring–applied saflufenacil at 50 g ai/ha provided 8 wk of greater than 90% residual control, and early spring–applied simazine provided 6 wk of greater than 90% control. When applied in late spring, saflufenacil was the only herbicide treatment that reduced horseweed densities by greater than 90% compared to 2,4-D + glyphosate. We concluded from this research that fall applications of nonresidual herbicides can increase the rate and density of spring emerging horseweed. In addition, spring-applied saflufenacil provides no-till producers with a new preplant herbicide for foliar and residual control of glyphosate- and ALS-resistant horseweed.

Downy Brome (Bromus tectorum) Control in Established Alfalfa (Medicago sativa)

1997 ◽  
Vol 11 (2) ◽  
pp. 277-282 ◽  
Author(s):  
Robert G. Wilson
Keyword(s):  
Regression Analysis ◽  
Medicago Sativa ◽  
Linear Relationship ◽  
Bromus Tectorum ◽  
Downy Brome

Two experiments were conducted near Scottsbluff, NE, to evaluate the efficacy of fall-and spring-applied herbicides for downy brome control in established alfalfa. Downy brome was effectively removed from established alfalfa, and alfalfa yield increased with fall applications of hexazinone, metribuzin, pronamide, and terbacil. Regression analysis indicated a linear relationship between alfalfa yield and downy brome biomass. Glyphosate or paraquat suppressed downy brome when applied to dormant alfalfa in the spring. If glyphosate or paraquat application was delayed until after alfalfa had resumed spring growth, injury was observed. Alfalfa yield did not increase following spring applications of glyphosate or paraquat.

Integrated Systems for Control and Management of Downy Brome (Bromus tectorum) in Cropland

Weed Science ◽  
1984 ◽  
Vol 32 (S1) ◽  
pp. 26-31 ◽  
Author(s):  
Gail A. Wicks
Keyword(s):  
Bromus Tectorum ◽  
Seed Quality ◽  
Perennial Grass ◽  
Perennial Grasses ◽  
Downy Brome ◽  
Grass Seed ◽  
Small Grains ◽  
Control And Management ◽  
Perennial Legumes

Downy brome (Bromus tectorumL. # BROTE) may be a troublesome weed in winter small grains, perennial legumes, perennial grasses grown for seed, and orchards. In Nebraska, winter wheat (Triticum aestivumL.) yields have been depressed 30% by downy brome populations of 11 to 22 plants/m2(8). In Oregon, downy brome densities of 108 to 160 and 538 plants/m2reduced yields by 40 and 92%, respectively (22, 23). In Idaho, wheat yields were depressed 20 to 40% with 55 to 110 plants/m2(18). Downy brome has also been shown to lower yields and quality of hay from infested fields of alfalfa (Medicago sativaL.) (29). In perennial grass seed fields, downy brome may cause a serious seed quality problem (16). Some grass seed lots have contained as much as 50 to 75% downy brome seed.

Effects of Repeated Herbicide Applications on Alfalfa(Medicago sativa)

Weed Science ◽  
1978 ◽  
Vol 26 (2) ◽  
pp. 151-153 ◽  
Author(s):  
D. G. Swan
Keyword(s):  
Medicago Sativa ◽  
Weed Control ◽  
Bromus Tectorum ◽  
Downy Brome ◽  
Crop Tolerance ◽  
Average Control

Six herbicides, simazine [2-chloro-4,6-bis(ethylamino)-s-triazine], propham (isopropyl carbanilate), terbacil (3-tert-butyl-5-chloro-6-methyluracil), carbetamide [D-N-ethyllactamide carbanilate (ester)], pronamide [3,5-dichloro(N-1,1-dimethyl-2-propynyl)benzamide], and secbumeton [N-ethyl-6-methoxy-N′(1-methylpropyl)-1,3,5-triazine-2,4-diamine] were applied annually for four years to establish forage alfalfa(Medicago sativaL. ‘Washoe’). Downy brome(Bromus tectorumL.) control ranged from 80 to 100%. The average control of broadleaf weeds was 90 to 100% with simazine, terbacil, and secbumeton, compared to 30 to 40% with propham, carbetamide, and pronamide. Only simazine and terbacil were phytotoxic to the alfalfa. Based on weed control and crop tolerance, secbumeton performed best on the coarsetextured soil in this experiment.

Downy Brome (Bromus tectorum) Vernalization: Variation and Genetic Controls

Weed Science ◽  
2018 ◽  
Vol 66 (3) ◽  
pp. 310-316 ◽  
Author(s):  
Nevin C. Lawrence ◽  
Amber L. Hauvermale ◽  
Ian C. Burke
Keyword(s):  
North America ◽  
Bromus Tectorum ◽  
Brachypodium Distachyon ◽  
Western North America ◽  
Downy Brome ◽  
Annual Grass ◽  
Vernalization Gene ◽  
Greenhouse Experiments ◽  
Winter Annual

AbstractDowny brome (Bromus tectorumL.) is a widely distributed invasive winter annual grass across western North America.Bromus tectorumphenology can vary considerably among populations, and those differences are considered adaptively significant. A consensus hypothesis in the literature attributes the majority of observed differences inB. tectorumphenology to differing vernalization requirements among populations. A series of greenhouse experiments were conducted to identify differences inB. tectorumvernalization requirements and link vernalization to expression of annual false-brome [Brachypodium distachyon(L.) P. Beauv.]-derived vernalization gene homolog (BdVRN1). Results from this study indicate that variation in time to flowering is partially governed by differing vernalization requirements and that flowering is linked to the expression ofBdVRN1.

The Biology of Downy Brome (Bromus tectorum)

Weed Science ◽  
1984 ◽  
Vol 32 (S1) ◽  
pp. 7-12 ◽  
Author(s):  
Donald C. Thill ◽  
K. George Beck ◽  
Robert H. Callihan
Keyword(s):  
United States ◽  
British Columbia ◽  
Triticum Aestivum ◽  
Bromus Tectorum ◽  
Southeastern United States ◽  
The United States ◽  
Early Spring ◽  
Western United States ◽  
Downy Brome ◽  
Perennial Grassland

Downy brome (Bromus tectorumL. # BROTE), also known as cheatgrass, downy chess, broncograss, Mormon oats, and junegrass, was introduced into the United States from Europe, apparently during the middle of the nineteenth century (11, 21). According to Mack (23), downy brome entered British Columbia, Washington, and Utah around 1890; and by 1928 it had reached its present range, occupying much of the perennial grassland in Washington, Idaho, Oregon, Nevada, Utah, and British Columbia. Today, downy brome is a widespread weed throughout most of Canada, Mexico, and the United States, except for the southeastern United States (5, 17). Some consider downy brome to be an important forage because it provides most of the early spring grazing for livestock in western United States rangeland (21). However, it is also considered a troublesome weed in rangeland (31), winter wheat (Triticum aestivumL.) (27), several other crops (29), and noncropland (32).

Downy Brome (Bromus tectorum) Interference in Winter Rye (Secale cereale)

Weed Science ◽  
1993 ◽  
Vol 41 (4) ◽  
pp. 557-562 ◽  
Author(s):  
Robert E. Blackshaw
Keyword(s):  
Seed Yield ◽  
Secale Cereale ◽  
Field Experiments ◽  
Bromus Tectorum ◽  
Growing Season ◽  
Early Spring ◽  
Winter Rye ◽  
Downy Brome

Field experiments over 3 yr at Lethbridge, Alberta, determined the effect of various downy brome densities and times of its emergence on winter rye biomass and seed yield. Downy brome reduced yields most when it emerged within 3 wk of rye, but densities of more than 100 downy brome m-2were required to reduce yields by 20 to 30%. The greatest reductions in rye biomass (28%) and seed (33%) yields over the 3 yr occurred when 400 downy brome m-2emerged with the crop. Downy brome, at densities up to 400 plants m-2, emerging 6 wk after rye or in early spring, reduced rye biomass and seed yield less than 10% in all years. Winter rye effectively shaded downy brome (40 to 90%) for much of the growing season.

Implications of late fall and early spring 2,4-D applications on subsequent canola production on Black, Dark Brown and Gray Wooded Soil

1997 ◽  
Vol 77 (4) ◽  
pp. 699-702 ◽  
Author(s):  
K. J. Kirkland
Keyword(s):  
Weed Management ◽  
Growth And Development ◽  
Early Spring ◽  
Brassica Napus L ◽  
Green Seed ◽  
Late Fall ◽  
Winter Annual ◽  
Annual Weeds ◽  
Fall Application ◽  
Made In

Late fall or early spring application of 2,4-D to control winter annual weeds prior to canola has not been recommended as the herbicidal effects on canola growth and development on varying soil types are not well defined. 2,4-D was applied to Black, Dark Brown and Gray Wooded soils located in west-central and northwest Saskatchewan. Applications were made in the fall and early spring prior to planting Brassica napus L. and Brassica rapa L. canola from 1992 to 1994 at the recommended (0.42 kg ha−1) and twice the recommended rate. The rate of 2,4-D applied had no effect on canola plant population, pods per plant, yield, green seed, chlorophyll, kernel or test weight. Application of 2,4-D in the fall had no effect on any variable while spring application reduced plant stands and increased green content but had no effect on pod production, yield or chlorophyll content. Late fall application of 2,4-D prior to canola in rotation should be recognized as a valuable addition to weed management in canola, particularly when direct seeding is practised. Key words: Canola, 2,4-D, soil residual, injury

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