Perennial grass emergence following indaziflam and imazapic applications on great basin rangelands

Authors: Clements, Darin - Charlie; Harmon, Daniel - Dan; QUICKE, HARRY - Bayer Cropscience

Submitted to: Society for Range Management
Publication Type: Abstract Only
Publication Acceptance Date: 11/8/2022
Publication Date: 2/7/2023
Citation: Clements, D.D., Harmon, D.N., Quicke, H. 2023. Perennial grass emergence following indaziflam and imazapic applications on great basin rangelands. Society for Range Management. 76:37.

Interpretive Summary:

Technical Abstract: Exotic and invasive annual grasses, such as cheatgrass (Bromus tectorum) continue to provide an early maturing fine-textured fuel that increases the chance, rate, spread and season of wildfires throughout the Intermountain West. Resource managers and landowners require viable tools to combat this ongoing challenge in an effort to reduce wildfire threats and improve grazing and wildlife resources. Chemical applications of soil-active pre-emergent herbicides has increased in popularity as well as applications on Great Basin rangelands. We tested the more widely used herbicide, Imazapic, to the recently introduced herbicide, Indaziflam on cheatgrass control and perennial grass seedling mergence. Due to reporting that Indaziflam is known to have a longer soil activity than Imazapic, we tested the seeding of perennial grasses on plots that were fallowed for 1, 2 and 3-years at our TS Ranch study site in northern Nevada. Cheatgrass control with Indaziflam ranged from 84.8 – 98.6%, while cheatgrass control with Imazapic ranged from 94.2 - 97.8%. Following the prescribed fallows on each plot, Native, Introduced and Native/Introduced perennial grass seed mixes were seeded using a no-till drill in October of the prescribed fallow period. Imazapic treated plots recorded the highest perennial grass emergence in the 3-year fallow, 109/m² in the Introduced seed mix while the highest recorded perennial grass density in the Indaziflam plots were recorded in the 2-year fallow, 32/m² in the Introduced seed mix. Native seed mix plots recorded the lowest perennial grass emergence, such as 2/m² in the Indaziflam 1-year fallow plots. The extended herbicide residue of Indaziflam appears to limit seedling emergence of perennial grasses in restoration and rehabilitation efforts, therefor resource managers and landowners should be aware of this residue activity and the extended time needed to recruit perennial grasses following cheatgrass control efforts with Indaziflam.