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United States Department of Agriculture

Agricultural Research Service

Title: Herbicides for Establishing Switchgrass in the Central and Northern Great Plains

Authors
item Mitchell, Robert
item Vogel, Kenneth
item Berdahl, John
item Masters, Robert - DOW AGROSCIENCES

Submitted to: BioEnergy Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 22, 2010
Publication Date: March 31, 2010
Citation: Mitchell, R.B., Vogel, K.P., Berdahl, J.D., Masters, R.A. 2010. HERBICIDES FOR ESTABLISHING SWITCHGRASS IN THE CENTRAL AND NORTHERN GREAT PLAINS. Bioenergy Research. (Online)

Interpretive Summary: Weeds interfere with switchgrass establishment. Our objectives were to determine the effect of selected herbicides on stand establishment and biomass yields of adapted upland switchgrass cultivars grown in Nebraska, North Dakota, and South Dakota. A separate experiment was conducted in Nebraska to determine if there were any differences among switchgrass ecotypes for herbicide tolerance to the optimal herbicide combination. Herbicides applied immediately after planting were different concentrations of atrazine, quinclorac, atrazine + quinclorac, imazapic, and quinclorac + imazapic. The effectiveness of each herbicide treatment was determined by measuring switchgrass stand frequency and biomass yield. In the year after establishment, imazapic often reduced switchgrass stands in comparison to the untreated control, and is not recommended for switchgrass establishment. Herbicide treatments effected biomass yields only in Nebraska. The herbicide by cultivar interaction was not significant for stands or biomass yields, indicating that the effects were consistent over the upland cultivars used in the trials. No differences were detected among switchgrass lowland and upland ecotypes for tolerance to atrazine and quinclorac. Applying atrazine plus quinclorac resulted in acceptable stands and high biomass yields, and appears to be an excellent herbicide combination for establishing switchgrass for biomass production in the Great Plains.

Technical Abstract: Weed interference limits switchgrass (Panicum virgatum L.) establishment from seed. Our objectives were to determine the effect of selected post-plant, pre-emergent herbicides on stand establishment and subsequent biomass yields of adapted upland switchgrass cultivars grown in three environments in the Central and Northern Great Plains. A separate experiment was conducted in eastern Nebraska to determine if there were any differences among switchgrass ecotypes for herbicide tolerance to the optimal herbicide combination. Herbicides applied immediately after planting were different concentrations of atrazine [Aatrex 4L®; 6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine], quinclorac (Paramount®; 3,7-Dichloro-8-quinolinecarboxylic acid), atrazine + quinclorac, imazapic {Plateau®; 2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-5-methyl-3-pyridinecarboxylic acid}, and quinclorac + imazapic. Herbicide efficacy was determined by measuring stand frequency of occurrence and biomass yield. In the year after establishment, imazapic often reduced switchgrass stands in comparison to the untreated control, and is not recommended for switchgrass establishment. Herbicide treatments impacted post-establishment year biomass yields only in NE. In the multi-state trials, the herbicide by cultivar interaction was not significant for stands or biomass yields, indicating that the effects of herbicides on switchgrass stands and biomass yields were consistent over the upland cultivars used in the trials. No differences were detected among switchgrass lowland and upland ecotypes for tolerance to atrazine and quinclorac. The application of atrazine plus quinclorac resulted in acceptable stands and high biomass yields, and appears to be an excellent herbicide combination for establishing switchgrass for biomass production in the Great Plains.

Last Modified: 10/30/2014