2-17380 150-162 APM ddj

A primary goal of managing invasive aquatic plants is to selectively control the target plant without impacting more desirable plant species. A native plant of concern is wild rice ( Zizania palustris L.). Wild rice provides habitat for fish and wildlife, is a food source for waterfowl, and is utilized by humans as a cereal grain. The objective of this study was to examine the sensitivity of three wild rice growth stages, seedling, young, and mature, to aqueous concentrations (0, 0.75, 1.5, and 2.5 mg ae L -1 ) of triclopyr. Plant control was rated on a 0 to 100% scale each week after treatment. At four weeks post treatment, plants were harvested, measured for height (cm), number of seedheads and tillers, and dried at 70 C to a constant mass. Wild rice exposed to the highest concentration of herbicide exhibited reduced height and mass regardless of life stage. The lowest triclopyr concentration did not significantly reduce height, biomass, seedhead density, or tiller formation. Wild rice seedlings exhibited the greatest sensitivity to triclopyr. Young and mature plants were less sensitive than seedling plants to triclopyr applications of 1.5 mg ae L -1 . A triclopyr concentration of 0.75 mg ae L -1 should have a negligible effect on all wild rice growth stages.