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Title: Pale swallow-wort establishment and survival across four disturbance regimes

item Milbrath, Lindsey

Submitted to: Proceedings of Northeastern Weed Science Society
Publication Type: Abstract Only
Publication Acceptance Date: 11/15/2007
Publication Date: 1/7/2008
Citation: Averill,, K.M., Ditommaso,, A., Mohler,, C.L., Milbrath, L.R. 2008. Pale swallow-wort establishment and survival across four disturbance regimes. In: G. R. Armel (Ed.), Proceedings of the 62nd Annual Meeting Northeastern Weed Science Society. p. 6.

Interpretive Summary:

Technical Abstract: Pale swallow-wort (Cynanchum rossicum (Kleopow) Borhidi) is an increasingly problematic invasive perennial vine in the northeastern U.S. and southeastern Canada. Currently, sufficient biological data on this herbaceous species is lacking. Such data are necessary for further development of a biological control program, already underway for this species. In November 2006, we planted pale swallow-wort seeds in old fields subjected to four disturbance regimes at two sites in central New York State. We hypothesized that emergence would be greater in treatments with greater disturbance. The treatments were: (1) an initial glyphosate (3.0 kg a.e. ha-1) and dicamba (1.9 kg a.e. ha-1) application followed by roto-tillage to 15 cm depth, (2) an initial glyphosate and dicamba application, (3) mowing to approximately 20 cm once per year, and (4) an undisturbed control. Here we present emergence and survival results from 2007. A concurrent seed stratification and germination trial for seeds collected at the same time and location as field-planted seeds was conducted under controlled conditions and resulted in 87 +/- 4 % germination. Seedling emergence was lower under field conditions. At the Mt. Pleasant field site, total emergence in the following growing season was 18 +/- 1 % and did not differ between treatments. At the Hanshaw field site, emergence varied by treatment (P < 0.001). At Hanshaw, mowed plots (21 +/- 3 %) had greater total seedling emergence than all other treatment plots: glyphosate + tilled (4 +/- 1 %), glyphosate (7 +/- 2 %), and control (11 +/- 2 %). Control plots had greater emergence than glyphosate + tilled plots. At Mt. Pleasant, May seedling emergence (as a percentage of total seedling emergence) was greater in the glyphosate + tillage (61 +/- 5 %) and glyphosate (52 +/- 11 %) treatment plots than in the control (5 +/- 3 %) and mowed (4 +/- 3 %) treatment plots (P < 0.001). At Mt. Pleasant, June seedling emergence did not vary between treatment plots, but in early July, control (33 +/- 10 %) plots had greater emergence than the more closed glyphosate + tilled (4 +/- 2 %) and glyphosate (3 +/- 1 %) plots (P = 0.01). Thus, emergence was delayed in control plots relative to the more open glyphosate and glyphosate + tilled plots. At Hanshaw, seedling emergence was not affected by treatment in any of the months. At both sites, seedling emergence declined after the first large flush. Most mortality occurred within the first three weeks after emergence at both sites and in all treatments. At both sites, survival to September of May- and June-emerging seedling cohorts was not affected by treatment. At Mt. Pleasant, which is at a greater elevation and is better drained than Hanshaw, the May cohort survival was 73 +/- 7 % and the June cohort had 88 +/- 3 % survival. At Hanshaw, the May cohort survival was 40 +/- 7 % and the June cohort had 43 +/- 9 % survival. These first-year results indicate that pale swallow-wort emergence and survival varies based on site and extent of disturbance. Here, elevation and soil drainage appeared to be factors contributing to the variations in pale swallow-wort emergence and survival between sites.