Degree
Doctor of Philosophy (PhD)
Department
School of Plant, Environmental, and Soil Sciences
Document Type
Dissertation
Abstract
The Lower Mississippi Alluvial Valley is a high-priority region for restoration of bottomland hardwood forests. Restoration of these forests is facilitated through conservation easement programs, such as the Conservation Reserve Program (CRP) and the Wetland Reserve Program (WRP), which focus on retiring marginal agriculture land and restoring bottomland hardwoods. A prominent issue that reduces hardwood establishment success is the failure to suppress competing vegetation, like eastern baccharis (Baccharis halimifolia L.), that aggressively colonize a site after seedlings are planted. Eastern baccharis is a frequent woody invader of disturbed bottomland sites throughout northeast Louisiana. There are few chemical options for controlling woody vegetation in bottomland hardwoods post-planting, making weed control difficult. Trials were conducted in 2020 and 2021 to evaluate the injury to planted trees and the chemical efficacy of eastern baccharis removal when triclopyr (Garlon® 4 Ultra) is applied post-emergent during the dormancy period of young (≤ 7 years) bottomland hardwoods. Trials compared aerially simulated chemical treatments to more conventional methods of baccharis removal, such as brush sawing, and brush sawing followed by cut-stump treatments using triclopyr. By the end of the second growing season there was no injury to planted bottomland hardwoods from any of the treatments evaluated. Cut-stump treatments indicated the highest efficacy of baccharis removal. Aerially broadcast rates of triclopyr had greater baccharis control than treatments with no herbicide and resulted similarly to cut-stump treatments. Trials were conducted in 2020 and 2021 to evaluate the vegetative response of the overstory and understory following treatment applications. No significant differences were detected in species richness or species diversity. A treatment and a treatment with date interaction effect resulting in greater visual obstruction in strata 2 from 2020 to 2021. Pre-treatment presence of non-native understory plants may have restricted species richness and diversity. Canopy openness was measured using hemispherical photography and no significant effect was found among treatments. Our research shows dormant season broadcast applications of ester formulated triclopyr as a viable approach to reduce coverage of eastern baccharis with minimal injury to planted hardwoods.
Date
11-1-2024
Recommended Citation
Stamper, Lucas, "Eastern Baccharis Control in Newly Planted Wetland Reserve Programs" (2024). LSU Doctoral Dissertations. 6633.
https://repository.lsu.edu/gradschool_dissertations/6633
Committee Chair
Webster, Connor