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Title: Emergence and performance of pale and black swallow-wort on two New York soils at three pH levels

item Milbrath, Lindsey

Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/15/2007
Publication Date: 2/4/2008
Citation: Magidow, L.C., Ditommaso, A., Ketterings, Q.M., Milbrath, L.R. 2008. Emergence and performance of pale and black swallow-wort on two New York soils at three pH levels. Weed Science Society of America Meeting Abstracts. No. 266. [CD-ROM]. Vol. 48. Lawrence, KS: Weed Science Society of America. (

Interpretive Summary:

Technical Abstract: Pale swallow-wort (Cynanchum rossicum [Kleopow] Borhidi) and black swallow-wort (Cynanchum louiseae [L.] Kartesz & Gandhi) are two herbaceous, perennial vines which are increasingly problematic invaders in the Great Lakes Basin of the Northeastern U.S. and Southeastern Canada. Although the North American ranges of these species are adjacent, so far they are only rarely observed to overlap. Preliminary observations from New York State indicate that pale swallow-wort may be associated with the high pH soils of Central NY and black swallow-wort with the low pH soils of Eastern NY. This two-year experiment examined the effects of soil type and pH on pale and black swallow-wort emergence and growth in a common garden experiment in Ithaca, NY. The performance of each species was assessed both (a) in the soil it was collected from and (b) in the soil the other species was collected from. Soil and seeds were collected from two locations in NY State heavily infested with pale swallow-wort (a Benson-Wassaic silt loam [Lithic Eutrudepts-Glossic Hapludalfs], Onondaga County) and black swallow-wort (Hollis sandy loam [Lithic Dystrudepts], Orange County). Three soil pH levels were established for each soil type (original pH, 4.5, and 8.0). The soil was then placed into drained pots, and in late fall of 2005 and 2006 swallow-wort seeds were sown on the soil surface to mimic seed rain. Seedling emergence was monitored in each pot, and of seedlings that emerged, six were randomly selected and allowed to grow until harvest. Before the first hard frost (early November), plants and roots were harvested and several growth parameters measured (e.g. stem length, dry stem and root biomass, node number). Average seedling emergence for the 2005 cohort was unexpectedly high (34%), while emergence for the 2006 cohort was much lower (15%). Soil type did not impact emergence in any year, but pH impacted emergence of both species in 2007; however, there were no consistent trends. Preliminary observations for plant growth in the 2005 cohort indicated complex three-way (species x soil type x pH) interactions. These inconsistent results suggest that habitats of varying soil type and pH may be equally suitable for colonization by swallow-wort, and that the growth and spread of these species are influenced by other factors.