Initial seeded perennial grass emergence following the application of rejuvra™

Authors: Clements, Darin - Charlie; Harmon, Daniel - Dan

Submitted to: Society for Range Management
Publication Type: Abstract Only
Publication Acceptance Date: 12/21/2020
Publication Date: 2/16/2021
Citation: Clements, D.D., Harmon, D.N. 2021. Initial seeded perennial grass emergence following the application of rejuvra™. Society for Range Management. 74:59.

Interpretive Summary:

Technical Abstract: The accidental introduction and subsequent invasion of cheatgrass (Bromus tectorum) throughout millions of hectares of Intermountain West rangelands has resulted in astronomical changes to many plant communities. Resource managers need tools to conduct aggressive and effective weed control practices on cheatgrass-infested rangelands to improve restoration/rehabilitation efforts. The use of pre-emergent herbicides can be very effective in decreasing cheatgrass densities which are limiting to the establishment of perennial species. Inazaflam, Rejuvra™, is a pre-emergent herbicide recently available for research on Nevada rangelands. In 2018 we initiated research to measure the efficacy of Rejuvra on cheatgrass control and perennial grass emergence in northern Nevada compared to the widely used pre-emergent herbicide, Imazapic Plateau®. Due to the environments of the cold desert, we applied these pre-emergent herbicides in the fall of the year, fallow the site for 1-year and then seed with desirable perennial species. Rejuvra plots plots reduced cheatgrass initial densities by 94.8%, while Plateau plots reduced cheatgrass densities by 97.8%. Following 1-year fallow, treated plots were seeded in the fall of 2019 to introduced native and introduced/native seed mixes using a no-till drill. In the spring of 2020, Rejuvra plots recorded significantly less initial emergence of perennial grasses in each seed mix compared to Plateau treated plots. Plateau plots recorded 16.7, 4.8 and 17.7 perennial grass seedlings/m² in the introduced, native and introduced/native seed mixes, respectfully. Rejuvra plots recorded 1.6, 0.5 and 5.9 perennial grass seedlings/m² in the same seed mixes. Amount and periodicity of precipitation is critical for germination and emergence, yet the site only received 14.38cm of precipitation from October 2019 through September 2020. It is also reported that Rejuvra may have a longer activity than the 12-15 months reported for Plateau, therefore, we set up-2-year fallow plots to test perennial grass emergence in additional Rejuvra treated plots.