| dc.description.abstract | Effective weed management is becoming increasingly difficult due to widespread herbicide resistance cases, lack of novel herbicide development, regulatory restrictions, societal pressures, and climate change. Integrated weed management strategies are crucial to overcome those limitations, and fundamental weed biology and ecology serve as the foundation for such strategies. Weed biology and ecology are influenced by numerous environmental factors, and while ample literature supports this statement, there remains a gap in knowledge regarding their holistic overlap with applied weed science. The overall objective of this research was to evaluate the impacts of environmental effects (CO2, moisture, edaphic factors) on weed biology, ecology, and management. Four unique experiments were conducted to meet this objective. First, a long-term bermudagrass forage system was evaluated to assess the impacts of elevated CO2 and weed/nutrient management on ecological shifts. After 7 years of no fertilizer or herbicide applications, weed density and diversity were much greater when exposed to elevated CO2 compared to ambient levels. Second, a greenhouse experiment was conducted to investigate the influence of various soil textures and moisture regimes on putatively-resistant Italian ryegrass (Lolium perenne L. ssp. multiflorum) growth and response to herbicides. High levels of resistance to pinoxaden and glyphosate were generally evident, but control using glyphosate was acceptable when plants were growing in clay soil under moisture stress. The few survivors in this treatment combination were subjected to lower intraspecific competition, which led to greater biomass and seed production compared to nontreated plants. Third, the ecology of weed emergence and the soil seedbank were analyzed at Auburn University’s historic Cullars Rotation. This long-term (>100 years) corn-cotton-wheat-soybean rotation revealed fascinating effects of soil amendments on crop growth and interactions with weeds. Plots with very poor fertility could not sustain adequate crop growth, whereas certain weeds like carpetweed (Mollugo verticillata), Florida pusley (Richardia scabra), southern sandbur (Cenchrus echinatus), large crabgrass (Digitaria sanguinalis), and Torrey’s rush (Juncus torreyi) dominated in these harsh conditions. Fourth, the soil seedbank and subsequent weed emergence were measured in an ongoing cover crop experiment at two sites in Alabama. Weed density and diversity differed between the two sites, but the effects of cover crops on weed ecology were not apparent. A few results suggested that crimson clover + cereal rye could be an effective mixture for reducing weed density and species richness, but further research is necessary to validate this observation. Overall, various environmental factors (CO2, soil texture, moisture, and fertility) significantly affected the ecology of weeds in various cropping systems. Future weed management plans need to consider such factors, as they can certainly influence weed competitiveness, invasiveness, and control. | en_US |
