Abstract:
Lespedeza cuneata was compared to three tall-grass prairie grasses: Andropogon gerardi, Andropogon scoparius, and Sorghastrum nutans. Research involved three major phases: first, to determine the optimum germination conditions for native seed; second, determine the effect of drought stress on the plant compared to the three grasses; and third, determine the effectiveness of different control methods for Lespedeza cuneata. Germination of seeds was determined over a range of temperatures and treatments using quartered germination trays to allow the four species to be subjected to the treatment at the same time. The highest percentages of germination were: Lespedeza cuneata at 40°C (30%) and a freeze-thaw regime at 30°C (39%); Andropogon gerardi at
25°C (72%); Andropogon scoparius with Metsulfuron methyl IIEscort®" at 30°C
(35%); and Sorghastrum nutans with light at 25°C (41%). Xylem pressure experiments with a 26-day drought stress were conducted in quartered pots so available soil moisture to the four species would be the same. Lespedeza cuneata appeared to have lower xylem pressure potential and was hardier than the grasses when experiencing water stress, but the test was inconclusive because of laboratory contamination. Control methods involved clipping or burning field plot areas that were infested with Lespedeza cuneata. The most effective control method for Lespedeza cuneata in reducing stem counts and weights was a treatment of clipping once in June and again in July; the next effective treatment was clipping every 30 days during the season, followed by a treatment of burning twice (spring/fall burn). The control method that was the least effective was a spring burn that seemed to promote the plant. Lespedeza seed germination appears to be promoted by high temperatures and by freezing and thawing, which apparently breaks down the seed coat. The grasses germinate better at cooler temperatures with the seedlings apparently promoted by the herbicide Escort®. Lespedeza cuneata appears to tolerate water stress
better than the native prairie grasses. And lastly, Lespedeza cuneata appears to be repressed by severe clipping twice (once in June and again in July) and promoted by the traditional spring burning of the Flint Hills.
