ARS | Publication request: Perennial grass establishment following cheatgrass control using herbicides

Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: July 26, 2012
Publication Date: February 3, 2013
Citation: Clements, C.D., Harmon, D.N. 2013. Perennial grass establishment following cheatgrass control using herbicides [abstract]. In: Proceedings of the Society for Range Management, February 3-7, 2013, Oklahoma City, OK. 66:15.

Technical Abstract: The introduction and subsequent invasion of Cheatgrass (Bromus tectorum) onto Intermountain rangelands has resulted in increased frequencies of wildfires and severely altered native plant communities. These destructive wildfires have negatively impacted wildlife and grazing resources as well as harm or threaten life and property. The ability of resource managers to have tools available to them to control such aggressive weeds as cheatgrass is instrumental in the success of rehabilitation and restoration efforts. The establishment of long-lived perennial grasses is the best known method at suppressing cheatgrass, decreasing cheatgrass fuels and wildfire frequencies. The objective of this study was to test the effectiveness of herbicides [Imazapic (Plateau), Rimsulfuron (Matrix), Sulfometuron Methyl (Landmark)] on controlling cheatgrass and allowing for the establishment of seeded species. Twelve plots, 25m x 50m, were established in fall 2010 and treated with 1) Imazapic at 6oz/ac, 2) Rimsulfuron at 4oz/ac, and 3) Sulfometuron Methyl at 1.75oz/ac rates and replicated 3 times in a completely randomized block design with controls. The treated plots were fallowed for one year and then seeded to Siberian wheatgrass (Agropyron fragilla ssp. sibiricum) at 7 lbs/ac rate. Siberian wheatgrass was selected because it performed and established at the highest rates from previous plant material testing. Sulfometuron Methyl yielded the highest control of cheatgrass above ground densities from 24.7/ft² down to 0.4/ft² (98.7%) followed by Imazapic, 17.6/ft² down to 0.8/ft² (95.6%) and Rimsulfuron 13.1/ft² down to 1.1/ft² (91.9%). The control plots averaged 39 cheatgrass plants/ft². Siberian wheatgrass seedlings emerged in March 2012 at fairly high densities (22.5/ft² in the Sulfometuron Methyl treated plots) and by mid-June 2012 still yielded excellent results in some of the treatments. Sulfometuron Methyl treated plots yielded 6.5/ft², followed by Imazapic, 4.1/ft² and Rimsulfuron, 1.5/ft². Control plots yielded 1.1/ft² despite only receiving 6.2” of annual precipitation. These numbers are expected to decline over the hot dry summer months before data is collected next spring, yet the Sulfometuron Methyl and Imazapic treated plots should result in sufficient long-lived perennial grass establishment to suppress cheatgrass densities in the near future.