Weeds

A weed is a plant in the wrong place, outside its noraml geographic range, with the potential to take over where it’s not wanted. Some previously well behaved plants have become outlaws in the Wet Tropics, thriving in local conditions, invading natural habitat and farmland, crowding out native species, or blocking waterways.

The number of known weed species in the Wet Tropics region has grown rapidly over the past 50 years to over 500 species and their spread is increasing alarmingly (about 200 new weed species have been identified in the past decade). The majority of plant species which have become weeds have been intentionally introduced into the region for agricultural,
horticultural or domestic purposes.

Weeds are generally associated with disturbed areas of ecosystems, although some may invade intact ecosystems. Many are highly invasive and can reproduce and spread rapidly in the absence of any natural controls. Weeds may disrupt ecosystems, compete with and replace native plants, reduce food and shelter for native species, change fire regimes and create soil erosion. Those weeds that can invade or transform pristine habitat are particularly threatening to the biodiversity of the WHA.

WONS weeds

Under the National Weeds Strategy, 20 introduced plants were identified as Weeds of National Significance (WONS). This list of 20 Weeds of National Significance was developed based on the following key criteria: 

• invasive tendencies 
• impacts
• potential for spread 
• socioeconomic and environmental values. 

WONS in the Wet Tropics include lantana, hymenachne, alligatior weed, cabomba, pond apple and salvinia.

Declared weeds in Queensland

The Land Protection (Pests and Stock Route Management) Act 2002 has now categorised new, highly invasive weeds as declared pest plants. Class 1 weeds are subject to eradication from the State. Class 1 weeds are not commonly present in Queensland and have the capacity to cause adverse economic, social or environmental impacts. Landowners (including State agencies) are now legally obliged to control Class 1 weeds on their land and State agencies and local governments must develop pest control plans.

Class 2 and 3 weeds are established in Queensland and have, or could have, an adverse economic, social or environmental impact. All landowners and managers must take reasonable steps to keep their land free of Class 2 weeds. Class 3 weeds have primarily environmental impacts and reasonable steps must be taken to keep significant environmental areas and adjacent areas free of Class 3 weeds. Local governments may also declare a weed specifically in their Council area. Currently, the resources required to meet these legal obligations are beyond the means of State Government and local government agencies.

There are also many weeds which have not yet been declared which require urgent attention or active preventative measures. In the Wet Tropics these include alligator weed, limnocharis, kosters curse, miconia, mikania vine, salvinia, siam weed and thunbergia sp.

You can read all about declared plants of Queensland on the Biosecurity Queensland website.

More information about weeds

The Weeds Australia website offers a comprehensive on-line search for weeds and their management.

The Biosecurity Queensland website will tell you all about declared weeds, environmental weeds, identification of weeds and control methods.