Location: Great Basin Rangelands ResearchTitle: Indaziflam soil activity after a one and two-year fallow
Submitted to: Society for Range Management
Publication Type: Abstract Only
Publication Acceptance Date: 1/5/2022
Publication Date: 2/22/2022
Citation: Harmon, D.N., Clements, D.D. 2022. Indaziflam soil activity after a one and two-year fallow. Society for Range Management. 75:81.
Technical Abstract: In the fight against exotic annual grass invasions in the Great Basin, one of the most effective tools is the use of pre-emergent herbicides. This class of herbicides prevent germinated seedlings from becoming established. They have minimal effect on established perennial plants and residual activity can last from a few months to years. Established plants avoid herbicide damage by having their roots deep into the soil profile below the shallow herbicide soil layer. Indaziflam is the key ingredient in Rejuvra ™, a pre-emergent soil-active herbicide for invasive annual grass control on rangelands. Rejuvra is a cellulose biosynthesis inhibitor (CBI) which can provide long term consistent weed control for up to four years. In northern Nevada pre-emergent herbicides are used to fallow the site, reduce cheatgrass (Bromus tectorum) competition and then (post herbicide activity) seed perennial grasses. Perennial grasses provide long term cheatgrass suppression, decrease annual grass fuels and associated wildfire risks. We designed an experiment to measure the activity of herbicide in the soil at various depths after both a 1 and 2-year fallow. We collected soil from two Rejuvra application sites in northern Nevada at 3 depths (0-2”, 2-4” and 4-8”) after 17 and 29 months from the herbicide application date. Soil was placed in 0.5 quart containers (n=6) in a greenhouse and seeded with cheatgrass and Siberian wheatgrass. Seedling survival was measured for comparisons. Soil from the top 0-2” profile from both sites after 1 and 2-year fallows drastically reduced cheatgrass and Siberian wheatgrass seedling survival (mean establishment = 11%). Survival in the 2-4” and 4-8” soil profile was significantly (P = 0.05) higher than then 0-2” profile, but did not significantly (p = .05) differ from control soil (no herbicide) (61% and 69% vs 71% control soil).