Dog Strangling Vine - An Invasive Species Creeping Into Agricultural Fields
Dog Strangling Vine is an extremely aggressive plant species from the milkweed family that has traditionally inhabited field borders, roadside and rail tracks. More recently it has been creeping into agricultural fields and pasture lands across Ontario, but mainly east of Toronto (see Figure 1). To minimize the impact of Dog Strangling Vine in these areas it is important to understand how this plant reproduces so that control measures are effective as possible.
Dog Strangling Vine is a perennial with a horizontal woody rootstalk or rhizome (Figure 2). The stems can range in length from 60 to 200 cm (24 80 inches) with a twining or scrambling configuration, hence giving it the strangling moniker. The leaves are ovate (oval) in shape, have smooth margins, with hairs being present on the margins and major leaf veins on the underside of the leaf (Figure 3). According to DiTommaso et al. 2005, the flowers of Dog Strangling Vine are a pink, red-brown or maroon, while Black Dog Strangling Vine has flowers that are dark purple to blackish. Flowers will produce pods containing seed that is similar in appearance to common milkweed.
General Reproduction and Biology
Dog Strangling Vine can reproduce by seed and by its massive underground root system (rhizomes). The seed is extremely viable once it germinates and the rhizomes can also propagate many new plants. An example of this was illustrated in a growth room experiment conducted at the Department of Plant Agriculture, University of Guelph. Every time a rhizome section was cut, two new plants would arise from each severed end.
In one season the vine has been known to grow as much as 1 to 2 m in size. Flowering generally begins in late-May and ends around mid-July. The fruit pods release seed from mid-August to early-November.
Control Options: Non-Chemical
The following is a summary of non-chemical control strategies that have been tested by Dr. Naomi Cappuccino, an assistant professor in the Department of Biology at Carleton University.
Control Options: Chemical
After a thorough literature search, only one herbicide label (Arsenal) lists Dog Strangling Vine as a species that will be controlled. There are a number of other products that have been tested and the results are shown in Table 2.
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Do you have Dog Strangling Vine?
If you are interested in evaluating some of the above control options, please call me at 519-824-4120 ext. 52580.
Figure 1. Distribution of Dog Strangling Vine in Ontario (Source: DiTommaso et al, 2005)
Figure 2. Cross Section through the woody rootstalk of Dog Strangling Vine (Source: DiTommaso et al, 2005)
Figure 3. Seedling of Dog Strangling Vine two weeks after emergence in a greenhouse (Source: DiTommaso et al, 2005)
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