Comparison of Mechanical Removal and Basal Bark Herbicide Treatments on Russian Olive Regrowth; Ron Patterson

 

 

 

Dennis Worwood¹, Ron Patterson²*, Corey Ransom³, Steven Price⁴

 

¹Utah State University Extension, Box 847, Castle Dale, Utah, USA; Retired

²University of Idaho Extension, 2925 Rollandet, Idaho Falls, Idaho, USA; dirtfarmagent@yahoo.com

³Utah State University, 4820 Old Main Hill, Logan, UT, USA; corey.ransom@usu.edu

⁴Utah State University, Carbon County, 751 E 100 N, Price, Utah, USA; steven.price@usu.edu

 

Mechanical removal of Russian olive (Elaeagnus angustifolia) without herbicide treatment typically results in a thick stand of root and crown suckers. Herbicide treatment after removal by machinery results in limited success due to the difficulty of finding the resulting stumps and exposed roots. Basal bark treatments kill epicormic buds on the lower trunk of the trees, but does not always kill the upper, central branches of older trees in particular. Root sucker formation arising from Russian olive removal requires the broken roots of removed trees to be at, or close to, the surface in order for adventitious bud development. It was hypothesized that basal bark treatment prior to mechanical removal may significantly reduce the development of epicormic and adventitious suckers. In May 2017, 360 Russian olive trees near Emery City, Utah were set up in a randomized block trial (N=3) with ten subsample trees in each treatment combination. Four removal treatments, skid steer mounted stump grinder, skid steer mounted tree saw, backhoe uprooting, and control (trees left standing), were compared. Removal treatments were crossed with three herbicide basal bark treatments of 20% triclopyr in MSO or diesel fuel (v/v) applied two weeks before mechanical removal and an herbicide control which was left untreated. Final evaluation on August 30, 2018 revealed that all mechanical × herbicide treatments reduced regrowth versus controls. All mechanical removal techniques without herbicide treatment also reduced regrowth versus controls. Basal bark treatments applied before mechanical removal significantly reduced epicormic and adventitious suckers. The most effective treatments were the triclopyr in diesel basal bark treatment with tree saw removal and triclopyr in MSO with stump grinder removal, each resulting in 97% control. Adoption of these herbicide treatment and removal techniques would significantly reduce the amount of regrowth and required labor-intensive retreatment of Russian olive after mechanical removal.