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Title: Vegetative Expansion of the Invasive Swallow-worts in New York State

item Milbrath, Lindsey

Submitted to: Proceedings of Northeastern Weed Science Society
Publication Type: Abstract Only
Publication Acceptance Date: 11/15/2008
Publication Date: 1/5/2009
Citation: Averill, K.M., Ditommaso, A., Mohler, C.L., Milbrath, L.R. 2009. Vegetative Expansion of the Invasive Swallow-worts in New York State. In: G.R. Armel (Ed.), Proceedings of Northeastern Weed Science Society. p. 40.

Interpretive Summary:

Technical Abstract: Pale and black swallow-wort [Vincetoxicum rossicum (Kleopow) Barbar. and V. nigrum (L.) Moench, respectively] are nonnative, perennial, herbaceous vines in the Asclepiadaceae. The species are becoming increasingly problematic in the northeastern United States and southeastern Canada. Management of the species has been challenging. Consequently, a classical biological control program was initiated in 2004 by the USDA-ARS with the goal of providing sustainable and economical long-term suppression of these two competitive species. Success of this biological control effort depends on the availability of plant demographic data, which can be modeled to determine which swallow-wort life stage(s) are likely to be most susceptible to control efforts. To determine the survival, rate of vegetative expansion, and fecundity of mature swallow-wort plants, we established demographic studies in 7 field sites in New York State. In 2005, we established 4 pale swallow-wort sites in Central NY, 3 of which had both old-field and forest habitats. In 2006, we established 3 black swallow-wort sites in old-field or disturbed habitats in the Hudson Valley. In each habitat, we measured the survival, expansion, and reproduction of 30 randomly-selected target plants of similar size (2-5 stems per plant in the establishment year). Pale swallow-wort yearly survival was 99.6 +/- 0.4% and 99.7 +/- 0.3% in old-field and forest habitats, respectively, and 100 +/- 0% in black swallow-wort habitats. Pale swallow-wort increase in number of stems from 2005 to 2008 was greater in old-field habitats (20 +/- 8% per yr) than in lower light forest habitats (2 +/- 4% per yr). From 2006 to 2008, the black swallow-wort increase in number of stems was 29 +/- 18% per yr. Preliminary data suggest greater pale swallow-wort fecundity in the old-field (600 +/- 200 seeds/plant/yr) compared with the forest (110 +/- 90 viable seeds/plant/yr) habitats. Black swallow-wort fecundity was approximately 430 +/- 50 viable seeds/plant/yr.