Introduced accidentally from South America, deeproot sedge is rapidly expanding in a variety of habitats throughout the southeastern United States. Of particular concern is its rapid expansion, naturalization, and formation of monocultures in Texas coastal prairie, one of the most imperiled temperate ecoregions in North America. The objective of this research was to examine how deeproot sedge responds to prescribed fire, to the herbicide imazapic, and to treatment combinations of both. Combinations of prescribed fire and imazapic treatments and imazapic-only treatments effectively reduced deeproot sedge cover and frequency. However, plots exposed to dormant season fires (with no imazapic) had greater deeproot sedge cover after burn treatments were applied, indicating that coastal prairie management using only dormant season prescribed fire will not work toward reduction or management of this exotic invasive species. Although deeproot sedge cover was often reduced in fire–imazapic treatment combinations, it was still present in treatment plots. Moreover, desirable functional plant groups (i.e., native bunchgrasses) did not respond positively to the fire–imazapic treatments, but in some instances, woody plant coverage increased. Repeated, long-term approaches using integrated and coordinated efforts with multiple treatment options will be necessary to restore community structure to desired compositional levels. Such integrated approaches should be effective in reducing deeproot sedge frequency, cover, and extent to more manageable levels throughout its introduced geographic range.
Nomenclature: Imazapic; deeproot sedge; Cyperus entrerianus Boeck.
Management Implications: This research is the first attempt, to our knowledge, to quantify the utility of prescribed fire, herbicide, and combinations thereof, to control deeproot sedge in coastal prairie. Prescribed fire alone, particularly during the time when most prescribed fires are performed (winter), did not work to reduce deeproot sedge cover or frequency. Specifically, combining imazapic and prescribed fire, with a long-term management goal of reimplementation of growing-season prescribed fire, should reduce deeproot sedge cover and frequency. Imazapic application can be effective throughout the growing season, both alone and in combination with prescribed fire, in reducing both the extent and the frequency of deeproot sedge. Both long- and short-term control will be dependent on effective monitoring of both aboveground plant and seed-bank response. As deeproot sedge produces a tremendous biomass (kg ha−1) of highly germinable seeds, seed bank management will remain a key element in restoration of invaded sites. This research provides some of the first evidence that deeproot sedge control may be achieved through integrated management with both imazapic and prescribed fire.