Korman, Brian L. , Larson, Gary E. , Butler, Jack L. , Nepal, Madhav P. .
Sickleweed, an Emerging Problem in the Northern Mixed Grass Prairie.
Sickleweed (Falcaria vulgaris, Apiaceae) is a common weed of Europe and western Asia where it is described asĀ annual, biennial, and perennial. Little is known of its biology and ecology in North America. During the past two decades, sickleweed has rapidly invaded 3240 ha of mixed grass prairie on the Fort Pierre National Grassland (FPNG) in central South Dakota. This study aimed to determine (1) sickleweed germination characteristics, (2) ability of sickleweed to spread vegetatively, and (3) impact of sickleweed on grassland productivity. Germination trials were conducted at the South Dakota State University Seed Laboratory using seeds collected from FPNG. Five temperature regimes, two light regimes, and two storage conditions (room temperature and at -15C) were tested. High germination rates (>73%) were obtained with all treatment combinations. We found the ability of sickleweed to generate new shoots from 4-cm root segments derived from upper, middle, and lower sections of the taproot, and we observed field planted sickleweed to produce numerous new shoots up to 1 m distant from parent plants in the second growing season after transplanting. New shoots aroise from upward-growing, tuberous branch roots originating from very deep in the ground. To evaluate the effects of sickleweed on other vegetation, peak standing crop was harvested from infested plots and compared to non-infested plots. Biomass of all plants in sickleweed infested plots was 23% lower than in non-infested plots (P<0.05). After one year of periodically removing the aboveground sickleweed biomass (clipped plots), total biomass in sickleweed clipped plots was about 10% higher than in sickleweed unclipped plots (P<0.05). Genetic analysis of FPNG sickleweed using AFLP and/or microsatellites is planned in order to compare our populations with other U.S. and Eurasian populations and to possibly assess sources and frequency of sickleweed introduction to the northern Great Plains region. Because sickleweed has such serious implications to the diversity and productivity of northern mixed grass prairie, FPNG is aggressively implementing control measures.
Sickleweed appears to have a novel mechanism of vegetative reproduction rendering it a highly successful weed in drought prone grasslands. New plants appear to arise from negatively geotropic roots that ascend from deep underground and form new shoots up to 1 meter away from the parent plant. We hope to analyze introduced populations to potentially determine their origin and to assist in identifying potential biocontrols.
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1 - South Dakota State University, Biology & Microbiology, Box 2207B, Brookings, SD, 57007, USA
2 - U.S. Forest Service, Forest and Grassland Research Laboratory, 8221 South Highway 16, Rapid City, SD, 57702, USA
3 - South Dakota State University, Biology and Microbiology and South Dakota State University Herbarium (SDC), Brookings, SD, 57007, USA
Presentation Type: Poster:Posters for Sections
Location: Hall A/Convention Center
Date: Monday, August 2nd, 2010
Time: 5:30 PM