Bryson, C.T., R. Carter and D. J. Rosen. 2003. Deeprooted sedge (Cyperus entrerianus). Proceedings, Southern Weed Science Society (Invasive Weeds Symposium), Volume 56 [208].

ABSTRACT

Deeprooted sedge (Cyperus entrerianus Boeck.) is a non-native invasive weed that has spread rapidly in the coastal plain of the southern United States.  First reported from the United States in 1990, it was apparently introduced from temperate regions of South America.  Currently in the United States, deeprooted sedge is a troublesome weed in 43 counties of Alabama, Florida, Georgia, Louisiana, Mississippi, and Texas.  Deeprooted sedge can be distinguished from related species by its robust growth form, deeply set thick rhizomes, dark purplish black leaf bases, and glossy leaves. Flooding, construction equipment, mowing, heavy traffic, and soil moving activities, especially along highways, spread its tiny seeds, resulting in infestations in new areas, particularly in disturbed habitats. Deeprooted sedge is displacing native vegetation even in undisturbed habitats. Without widespread control, deeprooted sedge will likely continue to spread rapidly, infesting agricultural, forested, riparian and urban areas.  In the southern United States, this perennial species reproduces by copious seed production and vegetative growth from short, woody rhizomes. Plants survive (>95%) winters as far north as Stoneville, MS, and, in a single growing season, plants grown from seeds weighed 1 to 1.8 kg/plant by frost.  In field studies, biweekly mowing prevented inflorescence production but did not control vegetative re-growth.  Clipping at 15 cm above soil prevented inflorescence formation and seed maturation.  Number of seed per inflorescence ranges from 1,000 to > 20,000 depending on the size and maturity of deeprooted sedge, and mature plants (> 1 year old) produced from 10 to over 100 inflorescences per year.  Deeprooted sedge re-growth was rapid and seed production was only temporarily suppressed (< one month) following a single tillage operation (disking).  Repeated tillage controlled established plants, but seedlings rapidly replaced them following rainfall with no additional tillage.  Of herbicide treatments tested in field trials, the most effective for deeprooted sedge control were glyphosate at 2.2 kg/ha (98%) or 1.1 kg/ha followed by 1.1 kg/ha (10 days apart) (95%), hexazinone at 0.28 kg/ha (92%), MSMA at 2.2 kg/ha (85%), glyphosate at 1.1 kg/ha (84%), halosulfuron-methyl at 0.07 kg/ha (80%), 2,4-D at 0.8 kg/ha + dicamba at 0.27 kg/ha (78 %), and 2,4-D at 2.2 kg/ha + picloram at 0.07 kg/ha (70%).  Additional spread of deeprooted sedge can be prevented by (1) cleaning machinery, vehicles, equipment, clothing and other personal items after use in infested areas to avoid spread;  (2) suppressing seed production by repeated mowing at 2 to 4 weeks intervals; and (3) applying herbicides and/or repeated tillage operations where and when possible.  Because deeprooted sedge continues to spread at an alarming rate threatening agricultural and natural areas and preliminary studies suggest that populations will potentially spread northward into Arkansas, North Carolina, South Carolina, Tennessee, and Virginia, additional research is needed to determine more effective methods of prevention and control.