APPENDIX E – Invasive Species Information Sheets strangling Vine has not yet invaded alvar communities in the SEZ, these communities should be closely monitored for invasions. Pale Swallow-wort is associated with calcareous soils, and this may also be true of Black Swallow-wort (Lawlor, 2001). The habitat in which it is found in parks has not been fully described. Dispersal: Wind dispersed. Impacts Dog-strangling Vine can form dense stands that exclude and may displace native vegetation - further research is needed to determine the impact of this on native plant communities (Lawlor, 2001). Toxic substances present in this species may also have allelopathic (suppress the growth of other species) properties. Laboratory trials have shown that Monarch butterflies (Danaus plexippus) will use Black Swallow-wort as an alternate host to lay their eggs on, rather than the native milkweeds. Larvae found on Black Swallow-wort experience high levels of mortality. It is possible that Monarch butterflies may also oviposit on Pale Swallow-wort. It is not yet known how and to what extent this may affect Monarch populations (Lawlor, 2001). Control Measures • Mechanical methods have not proven successful (Lawlor, 2001; McKewan, 2002; Cappuccino, 2002, Towel, 2002; Christensen, 1998). Both mowing and digging may actually stimulate growth (Cappuccino, 2002). Digging has the added disadvantage of disturbing the soil, which may promote more vigorous growth from the seed bank. If root crowns are dug up, they must be removed from the site, as crowns left on the ground can re-sprout (Lawlor, 2001) Mowing may be partially successful if this is carried out until the seed bank is depleted, but the site will need to be completely restored afterwards. Christensen (1998) found that repeated mowing reduced the average stem height, but did not have a great effect on total cover. Mowing should be carried out twice per growing season: once in mid-June, and again in early August. • Hand-pulling is not recommended, as root crown fragments in the soil will re-sprout (Lawlor, 2001). • Mulching has been attempted with both leaf litter and plastic sheeting. A common problem with this method is that animals will tear the sheeting, and plants can push through the mulch. Unless a tear resistant fabric can be utilized, this method is not recommended (Christensen, 1998). Again, this method kills all plants below the mulch or sheeting, and plastic sheeting can also kill soil microbes. • Fire may not be effective at reducing the number of mature plants in a colony, but may be useful after chemical application to remove seedlings, but further research is needed to substantiate this (Lawlor, 2001). • Chemical control is the most effective method (Lawlor, 2002; Christensen, 1998; McKewan). Glyphosate is recommended, as it is not persistent in the soil, and has a low level of toxicity in animals with no long term negative effects. Triclopyr has been tested on this species, and results were not as high as plants treated with glyphosate (Lawlor, 2002). Foliar spraying of herbicides appears to be the most successful application method, but this is only practical in monocultures. Cut-stem application (wicking stems and leaves of trimmed plants) provides species specific control, and is recommended in areas where the goal is to release surrounding vegetation. A 5% solution of glyphosate is required for foliar spraying, and a 50%+ solution for cut-stem application. This dosage is higher than recommended by the manufacturer. Application should be done at the bud <strong>Sandbanks</strong> <strong>Veg</strong>etation Management <strong>Plan</strong> A-17 <strong>Ontario</strong> <strong>Parks</strong>, SE Zone 2009
APPENDIX E – Invasive Species Information Sheets formation stage (early June), early in the flowering stage, and again in August (Lawlor (2002). Monitoring and control may be necessary in consecutive years to eradicate the colony, but it is not known how long seeds persist in the soil (Christensen, 1998; Lawlor, 2002). <strong>Sandbanks</strong> <strong>Veg</strong>etation Management <strong>Plan</strong> A-18 <strong>Ontario</strong> <strong>Parks</strong>, SE Zone 2009
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