The main purpose of the Weed Control Act R.S.O. 1990 is to reduce the impact of noxious weeds on the industries of agriculture and horticulture. Primarily this act applies to agricultural and horticultural lands that generate income or other benefits to agriculture; this excludes lawns, gardens and private areas for personal enjoyment and leisure.
Under the Weed Control Act, R.S.O. 1990, Chapter W.5 Sections 3, 13, 16 and 23, residents are requested to destroy all noxious weeds on their property.
In Urban Areas, Sections 3, 13, 16 and 18 do not apply to noxious weeds or weed seeds that are far enough away from any land used for agricultural or horticultural purposes, as they do not interfere with that use.
See link below on what is a noxious weed and the Weed Act. (http://www.omafra.gov.on.ca/english/crops/facts/noxious_weeds.htm)