Abstract:
The cold hardiness of cogongrass, Imperata cylindrica, and jOhnsongrass, Sorghum halapense, was studiec in growth chamber and greenhouse experiments. The cogongrass specimens were obtained in Florida and were grown in the growth chamber for rhizome production. Johnsongrass rhizomes were collected from a field near Emporia, Kansas. The harvested rhizomes were sized and subjected to different temperatures initially set at 25 C. Every two hours, the temperature was lowered by 5 C and rhizome sclllples Here taken for viability tests. Vi2bility was determined by using 1 %TIC solution and by planting the rhizomes. Cogongrass rhizomes were more sensitive to cold temperatures than johnsongrass. Its rhizomes were killed after exposure to 4 C, whereas johnsongrass rhizomes had -3 C tolerance limit. In addition, during the period of November 22 to February 9, some of the jOhnsongrass rhizomes survived the -4 C temperature treatment, i.e. showed slight acclimation to cold weather. It was concluded that cogongrass is not likely to become established in Kansas.
