Three of the �declared� pests are blackberry, morning glory and hydrocotyleranunculoides.
Under the Biosecurity and Agriculture Management Act 2007, �declared� means the weed is prohibited because of its adverse impact on people, the environment or agriculture.
Canning chief executive Lyn Russell said weeds found in natural bushland provided little support for wildlife, smothered native plants and increased competition for nutrients, water and space.
�An increase in short lived annual weeds can also increase the fire risk to bushland,� Ms Russell said.
�Weeds on sports grounds can smother the grass and create rough spots that can be hazardous for players.
�Prickly weeds in grass are uncomfortable for pets and for barefoot visitors, especially children near playgrounds.� To reduce the number of weeds entering bushland, the City recommends not dumping waste in bushland, choosing local native species in gardens and joining local bushland friends groups.
�The City will soon release a brochure about environmental weeds in the City of Canning, which will provide information on many of the environmental weeds in the City and what to do to reduce their impact,� Ms Russell said.
The City�s natural areas team works with contractors and community groups to control weeds.
Techniques include herbicide application, hand weeding, brush cutting, manual excavation and revegetation of weedy areas with native species.
Ms Russell said it was important to control the spread of weeds year round.
To report a weed infestation in a park or bushland area, call 1300 422 664.