A weed can generally be described as a plant growing where it is not wanted. The Department aims to prevent the introduction and spread of weeds within, into and from the Northern Territory. Legislation is in place to prevent the introduction and spread of noxious weeds in the Northern Territory.
Weeds are a major threat to natural and managed ecosystems.
Severe invasions can alter habitats by displacing native flora and fauna and decreasing biodiversity. Aquatic weeds can impact on recreational fishing by reducing the quality of fish habitat and making access to waterways difficult. Some waterways in National Parks are off limits to fishermen due to the presence of a noxious waterweed, Salvinia molesta . Weeds impact on primary industry by increasing the cost of horticultural production, reducing productivity of pastoral land, impeding stock mustering and choking and polluting water supplies. Weeds are spread by climatic conditions such as high winds and flooding, by domestic, feral and native animals, via contaminated stock, grain, machinery, and vehicles, and directly by people on their clothing and shoes.