Start Date: Dec 08, 2010
End Date: Dec 07, 2015
Foreign exploration will identify damaging natural enemies of swallow-worts in their native range. The fundamental host range of candidate biological control agents will be determined overseas and in quarantine. Swallow-wort tissue extracts will be assessed for allelopathic activity, a possible mechanism of invasion. Field-based plant demography studies will identify life stage transitions that strongly affect population growth rates of these invasive plants. Knowledge of these critical transitions will be used to guide the selection of potentially effective agents, a new approach for weed biological control in the U.S. Long-term defoliation/clipping studies will be conducted to document the rate of plant decline. Comparative surveys of areas infested and uninfested by pale swallow-wort will document its impact on plant density, cover and species richness of native ecosystems both before and after the release of approved biological control agents. Additional permanent monitoring sites will document changes in pale and black swallow-wort densities before and after release of agents. Establishment success of newly released agents will be evaluated.