|Madsen, Matthew - Brigham Young University|
|Hulet, April - University Of Idaho|
Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/17/2017
Publication Date: 8/7/2017
Citation: Davies, K.W., Madsen, M.D., Hulet, A. 2017. Using activated carbon to limit herbicide effects to seeded bunchgrass when revegetating annual grass-invaded rangelands. Rangeland Ecology and Management. 70:604-608.
Interpretive Summary: Revegetation of exotic annual grass-invaded rangelands would be improved if desired species could be seeded simultaneously with pre-emergent herbicide control of annuals. Non-target herbicide damage to seeded species has limited this approach and thus seeding is postponed until herbicide toxicity has diminished resulting in seeded vegetation experiencing competition from re-invading exotics. However, activated carbon can deactivate herbicides because of its high absorption capacity and potentially allow seeding to occur simultaneously with herbicide control of exotics. We evaluated if small pods (8 x 16 x 16 mm) containing activated carbon and seeds would allow a bunchgrass to be seeded at the same time as annual grasses were controlled with the pre-emergent herbicide imazapic. Bunchgrass abundance was 300% greater when seeded in activated carbon pods compared to bare seed. This suggests that activated carbon pods protected the bunchgrass from herbicide effects and that this approach could be used to seed desired species simultaneously with imazapic control of exotic annuals.
Technical Abstract: Revegetation of exotic annual grass-invaded rangelands is challenging as annuals rapidly reinvade after control treatments. The most effective control of exotic annual grass is usually achieved with pre-emergent herbicides, however, species seeded simultaneously with these herbicides will likely experience non-target damage. Thus, seeding often occurs one year later to reduce herbicide toxicity, but by this time annual grasses may already be reinvading and limit the success of seeded vegetation. Activated carbon can be used to protect seeded species from herbicide damage because it has a high absorption capacity that can deactivate many herbicides. Grow room studies suggest that a pod containing activated carbon and seeds, herbicide protection pods (HPPs), may allow desired species to be seeded at the same time as annual grasses are controlled with the pre-emergent herbicide imazapic. However, these HPPs have not been field tested. We evaluated two seeding treatments (crested wheatgrass (Agropyron desertorum [Fisch.] Schult.) incorporated into HPPs and bare seed) simultaneously with an imazapic application to control annual grasses at a cheatgrass (Bromus tectorum L.) and a medusahead (Taeniatherum caput-medusae (L.) Nevski) invaded site. Crested wheatgrass abundance was 300% greater with HPPs compared to bare seed in late June. Imazapic application reduced exotic annual grass density at both sites by approximately half. These results suggest that HPPs can be used to allow desired species to be seeded simultaneously with imazapic application. This will allow seeded species a longer window to become established prior to experiencing pressure from exotic annuals and allows for a single entry approach compared to multiple entries currently employed to revegetation annual grass-invaded rangelands. Though further field testing is needed, in particular with multiple species and higher herbicide applications rates, these results suggest that HPPs could improve our ability to restore and revegetate exotic annual grass-invaded rangelands.