Mapping, Control, and Revegetation of Cogongrass Infestations on Alabama Right-of-Way

01002086608608012004PDFTech ReportALDOT Research Project 930-486FallFireHerbicidesInterstate highwaysMappingMowingRevegetationRight of way (Land)SpringVegetationVegetation controlCogongrasscover cropsinfestationsDesignEnvironmentHighwaysPlanning and ForecastingI21: Planning of Transport InfrastructureUnited StatesAlabamaAlabama. Dept. of TransportationPatterson, MikeTeem, DavidFaircloth, WilsonAuburn University. Agronomy and Soils DepartmentAuburn University. Agricultural Experiment StationUS Transportation CollectionCogongrass is an undesired species on highway rights-of-way (ROW) due to its displacement of native and/or more manageable grasses, unsightly growth characteristic, and propensity for fire. Most importantly, ROWs provide corridors to un-infested areas, thereby expanding the range of this noxious weed. Two projects were located on Interstate 10 ROW in Baldwin Co. (AL), near Loxley (est. fall 2000) and Malbis (est. fall 2001). Both projects integrated herbicides with the subsequent revegetation of highly competitive and more desirable species. Mean control increased from 35% to 88% between a one and three year regime 12 months after treatment at Loxley. Mean control was greater at Malbis as control increased from 62% to 94% between the one and two year regimes. Fall herbicide treatments were ranked from highest control to least control as follows at Loxley: imazapyr alone, followed by the tank-mix of glyphosate plus imazapyr, followed by glyphosate alone. Fall-applied glyphosate plus imazapyr increased visual control and decreased stand density versus glyphosate alone in the study at Malbis. Spring re-treatment with glyphosate was needed to reduce density but not to increase visual control at Loxley, and was significant for neither visual control nor stand density at Malbis. The use of cover crops between fall and spring herbicide application was inconsistent in affecting control or stand density between both locations. The establishment of either bahiagrass or bermudagrass was achieved only at Malbis in a two year regime. A mowing by herbicide interaction study was also implemented to complement the Loxley and Malbis studies. Mowing alone neither positively nor negatively affected growth of cogongrass at frequencies up to twice per month. A sequential (spring followed summer) application of glyphosate gave complete above-ground control at the end of year one, however, regrowth was evident at the end of year two.75