A weed is a plant that is not native to an area and has the potential to dominate and out compete our native species. Most of the plants that are now weeds in Western Australia (WA) were introduced deliberately, as garden ornamentals, pastures or food
crops. Many of the weeds in WA come from Europe, South Africa, the Americas and eastern Australia.
Environmental weeds that compete with and displace local endemic plant species are a significant threat to natural areas. Weeds compete with local endemic plant species for space and light and deprive local fauna of suitable habitat. Controlling weeds
in natural areas is a significant cost to the management of these natural areas.
Approximately 197 weed species known to occur within the City of Kalamunda. The top ten priority weeds for the City of Kalamunda are:
- Bridal Creeper - Asparagus asparagoides
- Pampas Grass - Cortaderia selloana
- African Love Grass - Eragrostis curvula
- Freesia - Freesia aff. Leichtlinii
- One Leaf Cape Tulip - Homeria flaccida
- Tambookie Grass - Hyparrhenia hirta
- Victorian (Coast) Tea Tree - Leptospermum laevigatum
- Watsonia - Watsonia bulbillifera
- Blackberry - Rubus spp
- Paterson’s Curse - Echium plantagineum
On 1 June 1999 the inaugural list of 20 Weeds of National Significance (WoNS) was announced jointly by Commonwealth Ministers with a further 12 being added in 2012. The 32 Weeds of National Significance (WoNS) have been identified by Australian governments
based on their invasiveness, potential for spread and environmental, social and economic impacts.
The following weeds of national significance known to exist in the City of Kalamunda are:
- Blackberry - Rubus fruticosus agg.
- Boneseed - Chrysanthemoides monilifera
- Bridal Creeper - Asparagus asparagoides
- Flax Leaf Broom - Genista linifolia and Genista monspessulana
- Madeira Vine - Anredera cordifolia
- Opuntoid cacti – includes 27 species from three genera such as the Prickly Pear
- Lantana - Lantana camara
Many hardy and water wise garden plants can become weeds in local bushland areas. Some of these introduced plants have been promoted for use in gardens because of their low maintenance and water-wise properties. These plants have typically originated
in other parts or the world where there is a similar climate however, without any of the diseases or predators (such as insects that eat their seeds) that keep them in control in their natural environment, these plants have thrived and spread into
areas where they are not wanted such as bushland and neighbours’ properties.
The City of Kalamunda and its many bushland reserves and water courses are vulnerable to invasion of these plants. Garden Plants known to impact these areas include:
- Flinders Range Wattle - Acacia iteaphylla
- Veld Daisy - Dimorphotheca ecklonis
- Morning Glory - Ipomea indica
- French and Spanish Lavender - Lavendula dentate and L. stoechas
- Polygala - Polygala myrtifolia
Once a weed become established in an area, it is difficult to eradicate, expensive and requires more resources - prevention is the most effective method of dealing with weeds.
Some bushland weeds have escaped from gardens and due to their hardiness and fast growth, they are quick to establish and out-compete our endemic plants. Some native alternatives to garden plants with weed potential include:
- Australian bluebell - Billardiera heterophylla
- Holly flame pea - Chorizema ilicifolium
- Lemon scented darwinia - Darwinia citriodora
- Morning iris - Orthrosanthos laxus
- Purple flag - Patersonia occidentalis
- Native Wisteria - Hardenbergia comptoniana
Our Planting Guide contains some tips on how to ensure the success of planting native
Measures to help prevent garden plants escaping and becoming environmental weeds include:
- Choosing plants that are unlikely to become weeds in your area
- Checking existing garden plants and removing potentially weedy plants
- Disposing of garden waste appropriately
- Using mulch to reduce weed growth
Our Garden Escapees guide has more information on weeds and native alternatives.
The City controls weeds and carries out revegetation to eradicate invasive species and has a full time Bush Care Officer who undertakes on-ground weed control activities as well as providing valuable technical advice and on ground assistance to the many
Friends Groups in the City.
The method of weed control varies with the species being targeted and the amount of resources available. Integrated weed management through a long-term approach and using several techniques is best.
Control methods include:
- Physical – hay making, mowing, grazing, mulching, tiling, burning, hand removal
- Chemical – using herbicides via foliar spraying, basal bark spraying, stem injection, cut stump application, cut and swab method, stump scrape or wick application
- Cultural – practices to suppress weed growth and production, while promoting the development of the desired plant. This is usually used in farming systems, but some elements are relevant to landscape and bushcare practices
Prior to undertaking weed control, it is important to properly identify the species.
View some references and plant alternatives to assist in identification of weeds here.
It is a good idea to establish a field herbarium (i.e. a collection of pressed plants) of weed species as an ongoing reference.
An integrated weed management plan or strategy reduces the chance that weed species will adapt to the control techniques and will consider the most economical and effective control of the weeds and include ecological considerations. It will work to reduce
the extent of weeds and reduce the weed seed stock in the soil without degrading native ecology or agricultural potential.
Before using chemical control, please make sure the weed is identified correctly, an appropriate product is chosen, and this applied at the correct application rate using the safety measures recommended.
As well as the booklet on Garden Escapees and native alternatives, the City of Kalamunda worked in collaboration with the Shire of Mundaring and the Jane Brook Catchment to create a booklet titled Plants Out of Place
detailing 44 species of local weeds.
The variety of weeds include bulbs, grasses, herbs, rushes, shrubs, vines and creepers, along with some tips for identification, management practices and control techniques