Enhancing extension education recommendations to minimize spread of invasive species and establish new grasses for Georgia roadsides : final report.

Final reportPDFTech ReportFHWA-GA-16-123711852GrassesHerbicidesInvasive plantsMowingRoadside floraSeedingUnited StatesGeorgiaGeorgia. Dept. of Transportation. Office of ResearchMcCullough, PatrickShilling, DonnUniversity of GeorgiaGeorgia. Dept. of Transportation. Office of ResearchUnited States. Federal Highway AdministrationUS Transportation CollectionCurrent DOT management practices could be contributing to the release of invasiveweeds, such as broomsedge and vaseygrass, on Georgia roadsides. The herbicide imazapic, used toreduce mowing requirements of roadside grasses, injured bermudagrass twice as much as broomsedge,an invasive species, in greenhouse experiments. Imazapic provided no control of broomsedge in thefield. MSMA applied in fall provided good control of broomsedge for 1 year after initial treatment.However, imazapic tank-mixed with MSMA provided less control than MSMA alone, suggestingimazapic antagonizes efficacy of MSMA on broomsedge. The new herbicides Derigo and Pastoracontrolled or suppressed vaseygrass populations when applied in late spring. However, theseherbicides did not control broomsedge. MSMA will need to be applied in sequential programs whenALS inhibitors are used for other controlling other weeds or for growth regulation of roadside grasses.Introducing new grasses for roadside vegetation could reduce the spread of invasive weeds andenhance management. Centipedegrass and zoysiagrass have potential to establish under roadsideconditions as alternatives to bermudagrass and fescue in Georgia. These grasses effectivelyestablished when planted from sod or plugs. Centipedegrass was the quickest grass to establish fromsod. Growth of centipedegrass was comparable to zoysiagrass from plugs, and both species weremore competitive than bermudagrass under guardrails. None of the grasses established from seedunder simulated roadside conditions. Significant differences in vaseygrass germination were detectedby location. Vaseygrass seed germinated in June from collections in south Georgia. Seed germinationwas detected from July to November in Newnan, but other locations had minimal germination in fall.These results suggest that mowing operations could spread significant amounts of viable seedthroughout the state from June to November