Right-of-way management: A key to controlling the spread of cogograss (Imperata cylindrica)
Cogongrass [Imperata cylindrica(L.) Beauv.] is an undesired species on highway rights-of-way (ROWS) due to its displacenent of native and/or more manageable grasses, unsightly growth characteristic, and propensity for fire. Fire not only poses a danger to motorists but could cause property loss to adjoining landowners. Most importantly, ROWS provide corridors to un-infested areas, therefore, expanding the range of this noxious weed. In order to protect natural systems and un-infested areas, ROW management of cogongrass is crucial. Two projects were located on Interstate 10 ROW in Baldwill Co., near the towns of Loxley (est. fall 2000) and Malbis (est. fall 2001). Both projects integrated chemical control with the subsequent revegeration of highly competitive and more desirable species. Herbicides were glyphosate (3.0 lb ai/A) and imazapyr (0.375 and 0.75 lb ai/A). Repacement species were bahiagrass (Paspalum notatum var. Pensacola), common bermudagrass (Cynodon dactylon), browntop millet (Panicum ramosum), crimson clover (Trifolium incarnatum var. AU Robin), and annual ryegrass (Lolium multiflorum var. Gulf). Treatments were comprised of various combimations of herbicides and replacement species arranged in an RCB design with 4 replications. The initial study located at Loxley had 14 treatments plus an untreated control; the Malbis study consisted of 7 treatments plus an untreated control. Two differences in plot maintenance practices existed between locations: 1) p1ots at Loxley were not mowed during the growing season, and 2) all replacement species were broadcast-seeded. The study at Malbis was designed to more closely follow Alabama 1)Department of Transportation protocols, therefore, plots were mowed 4x during the growing season (May-June, July, Aug.-Sept., and Nov.) and all replacement species were drill-seeded. Plots were 15x30 ft. at both locations. Both studies were designed in triplicate, such that a time factor could be examined. All regimes were treated year one; two of three were re-treated in year two; a third was treated yet again in year three. Thus, all treatments could be evaluated when implemented in one, two, and three successive years. Plot evaluation included visual ratings of cogongrass control and subsequent revegeration, cogongrass stand counts, and cogongrass biomass sampling. Plots were evaluated yearly beginning one year after initial treatment (YAIT).