Activated carbon seed technology protects seedlings from two pre-emergent herbicides applied in tandem

Authors: Svejcar, Lauren; CLENET, DANIELLE - Oregon State University; Guetling, Christie; Davies, Kirk

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/27/2024
Publication Date: N/A
Citation: N/A
DOI: https://doi.org/10.1016/j.rama.2024.05.006

Interpretive Summary: Exotic annual grasses in the Great Basin are often controlled with pre-emergent herbicides. A commonly applied herbicide is imazapic. However, imazapic only demonstrates effective control of exotic annual grasses in one year. Thus, a new pre-emergent herbicide, indaziflam that was recently approved for use, is being applied with imazapic for longer term control. However, while applying herbicides is effective for controlling exotic annual grasses, it also kills desired species that are seeded for restoration. We found that incorporating desired species seed into herbicide protection pods helps to protect desired species from herbicide damage relative to bare seed.

Technical Abstract: In response to the challenge of simultaneously controlling invasive plant species and restoring desired species, seed technologies have been developed that use activated carbon to protect desired plants from pre-emergent herbicides that target invasive plants, such as herbicide protection pellets (HPPs). One ecosystem imperiled by this challenge is the sagebrush steppe of the Western United States. Land managers in the sagebrush steppe may use consecutive or concurrent applications of different pre-emergent herbicides in order to control invasive annual grasses while restoring desirable perennial vegetation that helps stabilize soil and reduce the frequency of wildfires. We conducted a pot study looking at the efficacy of HPPs for six perennial species with novel herbicide practices used by land managers: an application of both imazapic and indaziflam. The six test species included four bunchgrasses, one shrub, and one forb. The bunchgrass species responded well to the HPPs with similar seedling counts and biomass to bare seed when herbicide was not applied and higher seedling counts and biomass than bare seed when a double herbicide treatment was applied. Our results demonstrate that broader testing of HPPs with the application of both indaziflam and imazapic is needed, especially across wide climoedaphic field conditions.