Control of downy brome (Bromus tectorum) with herbicides and perennial grass competition
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Authors: T. D. Whitson, and D. W. Koch
Date: 1998
Journal: Weed Technology
Volume: 12
Number: 2
Pages: 391-396
Summary of Methods: Three experiments were set up to test the effectiveness of combining herbicides and perennial grass competition to control downy brome. The first two experiments tested three successive applications of glyphosate and paraquat were applied near Kaycee and Lusk to determine if the seed bank of downy brome could be reduced and if perennial grasses present in the rangeland understory could be competitively dominant. For 3 successive years paraquat was applied at four rates, glyphosate was applied at three rates and at two growth stages (two- to eight-leaf stage and the bloom stage). Both sites were intensely grazed by cattle 30 days after herbicide application for 90 days at Kaycee, and 80 days at Lusk. The first year of the study cattle were not grazed on the treatment plots. Canopy cover measurements to taken at each site. The third experiment at Riverside examined the ability of perennial grasses to establish and effectively compete with downy brome was tested at a site that was farmed but was not reseeded therefore, missing a perennial understory. Downy brome and musk thistle (Carduus nutans l.) dominated the site. Five cool-season perennial grasses (Critana thick-spike wheatgrass; Bozoisky Russian wildrye; Sodar streambank wheatgrass; Luna pubescent wheatgrass, and Hycrest crested wheatgrass) were seeded in the beginning of May. All species were seeded at a rate of 11 kg/ha with the exception of Russian wildrye, which was seed at 6 kg/ha. Each site was clipped and forage was sorted by species for annual production measurements.
Article Summary / Main Points: Herbicide treatments at Kaycee and Lusk, WY: 1) Glyphosate, at 0.55 kg/ha, and paraquat at 0.6 kg/ha provided selective control of downy brome when combined with intensive grazing. 2) Glyphosate at 0.69 kg/ha or more reduced perennial grasses available for competition with downy brome. 3) Paraquat was more effective than glyphosate when applied at early bloom stage. Perennial grass reseeding following fall tillage at Riverside, WY: 1) Three of the five cool-season grasses were successful at controlling downy brome. 2) Luna pubescent wheatgrass, Hycrest crested wheatgrass, and Sodar Streambank wheatgrass reduced downy brome dry matter production by 100, 91, and 85% respectively. 3) Bozoisky Russian wildrye and Critana thickspike wheatgrass reduced downy brome dry matter production by 45 and 32% respectively.
Vegetation Types: Shortgrass Prairie
MLRA Ecoregions: 34A Cool Central Desertic Basins and Plateaus 58B Northern Rolling High Plains, Southern Part 64 Mixed Sandy and Silty Tableland and Badlands
Agrovoc Control Words: Bromus tectorum Weed control Weeds
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: herbicide control, downy brome, cheatgrass, herbicide and intensive grazing, competitive perennial grasses
Annotation: This article provides important information on the use of two herbicides for controlling downy brome. However, the two herbicides used are two of many herbicides available for use in controlling downy brome and the reader should realize that other herbicides are available. Most importantly, this article is an important example of how perennial grasses can be used to successfully control cheatgrass; although, streambank wheatgrass (Elymus lanceolatus) was the only native grass used in this study.
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