Regulation - LGIC

Updating the Schedule of Noxious Weeds in R.R.O. 1990, Regulation 1096 - General, made under the Weed Control Act, R.S.O. 1990, c. W.5 (removal of milkweed and addition of dog-strangling vine)

Regulation Number(s):
Regulation 1096 - General
Bill or Act:
Weed Control Act, R.S.O. 1990, c. W.5
Summary of Decision:
The proposal has been approved. The amendments to the Schedule of Noxious Weeds in R.R.O. 1990, Regulation 1096 - General made under the Weed Control Act, R.S.O. 1990, c. W.5 are now in effect. The designation of milkweed species (scientific name Asclepias spp.) has been removed from the Schedule of Noxious Weeds.

The proposal included the addition of a plant species to the Schedule of Noxious Weeds under the common name dog-strangling vine. A plant species can have multiple common names and multiple plant species can sometimes be referred to by the same common name. Stakeholder feedback and input from experts clarified that the two related, but distinct, plant species present in Ontario that could be referred to by the common name dog-strangling vine should be listed separately as dog-strangling vine (scientific name Vincetoxicum rossicum) and black dog-strangling vine (scientific name Vincetoxicum nigrum (L.) Moench).

Vincetoxicum rossicum may also be referred to by other common names (including swallowwort, pale swallow-wort and European swallow-wort). Vincetoxicum nigrum (L.) Moench may also be referred to using other common names (including black swallow-wort and Louise's swallow-wort). The approved proposal uses the common names dog-strangling vine and black dog-strangling vine, together with their respective scientific names (as stated above).
Further Information:
Proposal Number:
Posting Date:
February 28, 2014
Summary of Proposal:
The purpose of the proposal is to amend the Schedule of Noxious Weeds in the Regulation in order to remove milkweed spp. and to add dog-strangling vine as prescribed noxious weeds.
Under the Weed Control Act (the Act), every person in possession of land is obligated to destroy all noxious weeds on it. However, this duty does not apply to noxious weeds or weed seeds that are far enough away from any land used for agricultural or horticultural purposes that the weeds or weed seeds do not interfere with that use. As a result, any person in possession of land where prescribed noxious weeds are present, and which could negatively affect lands used for agricultural or horticultural purposes, is responsible for controlling any prescribed noxious weeds present on it. Under the Act, the person in possession of the land may also be held responsible for the costs associated with removal. Depending on the lands and the conditions of use, this responsibility could rest with landowners (including farmers), municipalities and conservation authorities, among others.
The Schedule of Noxious Weeds lists milkweed spp. as the common name of the weed and Asclepias spp. as the scientific name of the weed. This description is very broad. As written, the term could extend to all species in the Asclepias genus, which includes many individual species, including four-leaved milkweed (a species at risk in Ontario) and other species in the Asclepias genus that are not considered a threat to agriculture or horticulture in Ontario.
The species common milkweed (Asclepias syriaca) has traditionally been viewed as a noxious weed in Ontario. It is considered to be common to widespread in many parts of southern and northern Ontario and it forms an important part of the native and naturalized vegetation in the province. Common milkweed also provides an important habitat and a larval food source for the Monarch butterfly. Milkweed species also play a key role in biodiversity in Ontario. The presence of common milkweed on lands that are not being actively farmed would be considered a low to negligible risk to activities on nearby agricultural or horticultural lands. Farmers can take proper management steps on their own lands to reduce the threat that common milkweed can pose to grazing livestock. Since milkweed spp. was added to the Schedule of Noxious Weeds initially, there has been an expansion in the number of management options available to farmers to address common milkweed on lands that are actively farmed.
Dog-strangling vine occurs in several places in southern Ontario, growing in ravines, hillsides, waste areas, fence lines and hedges. It forms dense patches and can overwhelm other vegetation, including agricultural crops. It is an invasive plant that can be difficult to control once established. Although the Monarch butterfly is attracted to the plant, any eggs laid will not survive. It is, therefore, considered a hazard to Monarch butterfly populations.
Contact Address:
Mike Cowbrough
Weed Management Field Crops Program Lead
Ministry of Agriculture and Food
Economic Development Division
Agriculture Development Branch
University of Guelph Office
50 Stone Road East
Crop Science Building, University of Guelph
Guelph Ontario
Effective Date:
May 8, 2014