Known Declared Weeds in the Kimberley
Bellyache Bush (Jatropha gossypiifolia)
Legal status: Declared Pest - s22(2).Presence in WA: Present.
Control / Keeping categories C3 – Management. Should have some form of management applied that will alleviate its harmful impact, reduce the numbers or distribution and prevent or contain its spread.
Bellyache bush has been recognised in Australia as a Weed of National Significance. It is generally acknowledged that the shallow root system and canopy cover of bellyache bush precludes growth of other plants, often out competing native vegetation and reducing pasture growth. Dense infestations may occur on river flats and other areas of good loamy soil. Bellyache bush has taken over extensive sections of river frontage in several locations, reducing biodiversity and increasing mustering costs.
The plant is widespread and increasing its range within both the Ord and Fitzroy River catchments in the Kimberley.
More informationChinee Apple (Ziziphus mauritiana)
Legal status: Declared Pest - s22(2).Presence in WA: Present.
Control / Keeping categories C3 – Management. Should have some form of management applied that will alleviate its harmful impact, reduce the numbers or distribution and prevent or contain its spread.
Dense infestations of chinee apple (Taylor fruit) create impenetrable thickets that seriously hamper stock management, reduce pasture production and accessibility. Mature trees produce large quantities of fruit that are readily eaten by stock, feral pigs, wallabies and birds, which assists the spread of the seed. Damage to top parts of the plant usually ensures vigorous regrowth from lignotubers or cut roots.
Chinee apple is present across the Kimberley, particularly around town sites and communities.
Flannel Weed (Sida cordifolia)
Legal status: Permitted - s11.Presence in WA: Present.
Control / Keeping categories is permitted - s11 for the whole of state and is not assigned to any control category for a local government area at this time.
An introduced species with a pantropic distribution naturalized in WA, NT, QLD and southwards as far as north-eastern NSW.
Altitudinal range in northern Australia from near sea level to 800 m. Usually grows as a weed of agricultural land and waste places but also found in disturbed areas and along roads in rain forest, monsoon forest and vine thickets.
More informationGamba Grass (Andropogon gayanus)
Legal status: Declared Pest, Prohibited - s12.Presence in WA: Present.
Control / Keeping categories C2 - Eradication / Prohibited. Should be eradicated from part or all of Western Australia.
Gamba grass is a weed of National Significance and is regarded as one of the most significant threats to northern Australia because of its invasiveness, potential for spread, economic impacts and environmental impacts. Gamba grass currently affects up to 15,000 square kilometres of the Northern Territory but has the potential to affect a further 380,000 square kilometres with most infestations currently north of Katherine. There is also estimated to be a total of 60,000 hectares spread across Queensland's north.
A small infestation is currently being controlled on El Questro Station in the East Kimberley.
More informationGiant sensitive plant (Mimosa pigra)
Legal status: Declared Pest - Prohibited - s12.Presence in WA: Present.
Control / Keeping categories C2 - Eradication / Prohibited. Should be eradicated from part or all of Western Australia.
Mimosa pigra (as it's more widely known as) is a Weed of National Significance. It forms dense impenetrable thickets, 3−6 m high, establishing on waterways, flood plains and wetlands. Accessibility to water for stock, irrigation and recreation purposes is affected. Pastures are smothered, reducing available grazing area and making stock mustering difficult. Dense growth eliminates most other species and alters the natural habitat in conservation areas. In the Northern Territory, some 80,000 ha of floodplain have been covered by the plant. Mimosa pigra’s invasiveness is due to its aggressive growth. In experiments in the Northern Territory, regrowth from young plants severed at ground level reached a height of 2.5 m and covered an area of 6.3 m2 within 12 weeks.
The plant is present in three locations in the East Kimberley with control programs allocated to all of them.
More informationGrader Grass (Themeda quadrivalvis)
Legal status: Declared Pest - s22(2).Presence in WA: Present.Keeping category: Exempt. No permit or conditions are required for keeping.
Grader grass is native to India. It was accidentally introduced to Australia in the 1930s as a contaminant in pasture seed and then in the 1960s to the Northern Territory. It is now well-established in the Katherine and Darwin regions and continues to spread.
Grader grass has spread rapidly along the east coast of Queensland, as well as into drier inland areas. It is now a major weed, especially in northern and coastal central Queensland where infestations continue to expand.
In the semi-arid monsoonal areas of northern Australia grader grass has the potential to be a significant threat to productivity. It invades native and improved pastures, forms virtual monocultures and competes with pasture species in over-used or disturbed areas. It can lead to a loss of productivity and increased fire risk, it proliferates and spreads along and from roads.
The plant is present along both the Gibb River and Kalumburu Roads in the Kimberley and is rapidly expanding along their lengths.
More informationIvy gourd (coccinia grandis)
Legal status: Declared Pest. Prohibited s12.Presence in WA: Present.
Control / Keeping categories C2 - Eradication / Prohibited. Should be eradicated from part or all of Western Australia.
In Australia Ivy gourd has been recorded in three states including the Kimberley region of Western Australia. It is believed to be native to central Africa, India and Asia however, its long history of use, cultivation and transportation by people has obscured its origin. It is a fast-growing perennial vine that grows several metres long, it can form dense mats that readily cover shrubs and small trees. It grows in dense blankets, shading other plants from sunlight and hijacking nutrients, effectively killing vegetation underneath.
More informationLantana (Lantana camara)
Legal status: Declared Pest, Prohibited - s12.Presence in WA: Present.
Control / Keeping categories C1 - Exclusion / Prohibited. Should be excluded from part or all of Western Australia.
Lantana is a Weed of National Significance. It is regarded as one of the worst weeds in Australia because of its invasiveness, potential for spread and economic and environmental impacts. Lantana forms dense, impenetrable thickets that take over native bushland and pastures on the east coast of Australia. It competes for resources, reduces the productivity of pastures and forestry plantations. It adds fuel to fires and is toxic to stock.
Lantana is a serious threat to biodiversity in several World Heritage-listed areas including the Wet Tropics of northern Queensland, Fraser Island and the Greater Blue Mountains and is listed as the most significant environmental weed by the South-East Queensland Environmental Weeds Management Group.
The plant is present in the Kimberley, mainly in and around town sites such as Kununurra but is yet to become the threat it poses for the environment as it has on the east coast.
More informationMesquite (Prosopis species)
Legal status: Declared Pest, Prohibited - s12- s22(2).Presence in WA: Present.
Control / Keeping categories C3 - Management / Prohibited. Should have some form of management applied that will alleviate harmful impacts, reduce the numbers or distribution or prevent or contain the spread on Mardie and Karratha Stations.
Mesquite is a Weed of National Significance and is regarded as one of the worst weeds in Australia because of its invasiveness, potential for spread, and economic and environmental impacts. There are four species and several hybrids of the weed, which are all collectively known as mesquite currently in Australia. It is widespread across northern Australia particularly in Queensland.
The Mardie Station infestation (150,000 ha) in the Pilbara is the largest single core infestation in Australia.
The weed is scattered across the Kimberley in low numbers with the exception of infestations on Yeeda and Nicholson Stations in the west and East Kimberley respectively. Both these sites have ongoing control programs on them.
More informationNeem (Azadirachta indica)
Legal status: Declared Pest - s22(2).Presence in WA: Present.
Keeping category: Exempt. No permit or conditions are required for keeping.
Neem has proven to be highly invasive and competitive. Deep tap roots and extensive lateral roots enable neem trees to flourish, even in areas affected by seasonal drought. It invades and competes with native plant species even in intact environments, produces a prolific amount of seed, which are readily dispersed and will dominate many riparian environments.
Neem is widespread in the Kimberley, particularly around town sites and communities. It is currently rapidly spreading throughout the Ord and Fitzroy catchments.
More informationNoogoora burr (Xanthium strumarium)
Legal status: Declared Pest - s22(2).Presence in WA: Present.
Control / Keeping categories C3 - Management / Exempt. Should have some form of management applied that will alleviate harmful impacts, reduce the numbers or distribution or prevent or contain the spread.
Noogoora burr is one of the most serious and widespread weeds in the world. It is mainly found in areas with high rainfall and a temperate climate but it may also persist in arid environment where the seeds may remain dormant for years and then take advantage of occasional rainfall to reproduce. The total infested area in Australia exceeds two million hectares.
Much of the Ord and Fitzroy catchments in the Kimberley are infested with the weed.
More informationOlive Hymenachne (Hymenachne amplexicaulis)
Legal status: Declared Pest, Prohibited - s12.Presence in WA: Present.
Control / Keeping categories C2 - Eradication / Prohibited. Should be eradicated from part or all of Western Australia.
Hymenachne was introduced to Australia from South America to provide ponded pasture for cattle. It has become an unwanted pest of stream banks, wetlands and irrigation ditches in coastal and central areas of Queensland. In some areas it has invaded low-lying sugarcane, fish habitats and natural wetlands with high conservation value.
Hymenachne can increase flooding by reducing the flow capacity of the drainage networks. Under flood conditions, plant material builds up at fences and bridges, collecting other floating debris and the combined weight may cause such structures to collapse.
Hymenachne has been recognised as a Weed of National Significance. One small infestation currently is being controlled by the land manager on El Questro Station in the East Kimberley. It is believed the plant was brought onto the site on a tourist's vehicle.
More informationParthenium weed (Parthenium hysterophorus)
Legal status: Declared Pest. Prohibited s12.Presence in WA: Present.
Control / Keeping categories C2 - Eradication / Prohibited. Should be eradicated from part or all of Western Australia.
Parthenium is a vigorous species that colonises weak pastures with sparse ground cover. It will readily colonise disturbed, bare areas along roadsides and heavily stocked areas around yards and watering points. Its presence reduces the reliability of improved pasture establishment and reduces pasture production potential.
Parthenium is also a health problem as contact with the plant or the pollen can cause serious allergic reactions such as dermatitis and hay fever.
There has been only one confirmed sighting of the plant in the Kimberley at the WA/NT quarantine yards east of Kununurra.
Parthenium is listed as a Weed of National Significance.
More informationParkinsonia (Parkinsonia aculeata)
Legal status: Declared Pest - s22(2).Presence in WA: Present.
Control / Keeping categories C3 - Management / Exempt. Should have some form of management applied that will alleviate harmful impacts, reduce the numbers or distribution or prevent or contain the spread.
Parkinsonia is a Weed of National Significance. It is regarded as one of the worst weeds in Australia because of its invasiveness, potential for spread, and economic and environmental impacts. Parkinsonia threatens rangelands and wetlands around Australia. If left untreated, it displaces native vegetation and reduces access to land and waterways. Economic costs to landholders stem from an increased difficulty in mustering stock, a reduction in stock access to watering points and a decrease in primary production of grasses that are replaced by parkinsonia. Additionally, parkinsonia infestations provide refuges for feral animals, especially pigs.
The environmental impacts of parkinsonia are numerous. Native plant species are replaced, leading to lower quality habitat for animals. Wetlands are particularly vulnerable because parkinsonia can dam watercourses, cause erosion, lower water tables and take over vast tracts of floodplain. Threatened areas include national parks and other regions of high aesthetic, indigenous and tourist value.
Parkinsonia is one of the most widespread weeds threatening pastoral activities in the Kimberley.
More informationPraxelis (Praxelis clematidea)
Legal status: Declared Pest. Prohibited s12.Presence in WA: Present.
Control / Keeping categories C2 - Eradication / Prohibited. Should be eradicated from part or all of Western Australia.
Native to South America, praxelis is an annual short-lived perennial herb found in Queensland in 1993. It is seen as a threat to cultivation, grasslands and conservation areas as it is highly invasive. It is an invader of both disturbed and relatively undisturbed ecosystems and could threaten and significantly increase the costs of managing, such crops as bananas, other fruit and sugar cane. It could infest pastoral grasslands and conservation areas, particularly open eucalypt woodlands.
A small infestation is currently being controlled on rural land just north of Kununurra.
More informationPrickly acacia (Vachellia nilotica)
Legal status: Declared Pest, Prohibited - s12.Presence in WA: Present.
Control / Keeping categories C2 - Eradication / Prohibited. Should be eradicated from part or all of Western Australia.
Prickly acacia is a Weed of National Significance and is regarded as one of the worst weeds in Australia because of its invasiveness, potential for spread, and economic and environmental impacts. At present over 6.6 million ha of Queensland is infested and it’s found in scattered populations across the NT with a substantial infestation in the southern Victoria River district.
Currently there are two known infestations in the Kimberley spread over approximately 10,000ha. Both are currently being controlled and are on track for eradication.
More informationRubber bush (Calotropis procera)
Legal status: Declared Pest - s22(2).Presence in WA: Present.
Keeping category: Exempt. No permit or conditions are required for keeping.
Rubber bush is native to tropical Africa and Asia. It was probably introduced to Australia as a garden plant, or in the packaging of camel saddles brought from India in the early 1900s. It poses a significant risk to valuable grazing land in the Kimberley by competing with native pastures.
Rubber bush can have all of the following impacts:
- poisonous to humans and stock
- can form dense thickets on disturbed and degraded soils
- competes with native pastures and smothers native plants
- inhibits access to watering points and restricts mustering.
The plant is widespread across the East Kimberley but much less prevalent in the west.
More informationRubber Vine (Cryptostegia grandiflora)
Legal status: Declared Pest, Prohibited - s12.Presence in WA: Present.
Control / Keeping categories C2 - Eradication / Prohibited. Should be eradicated from part or all of Western Australia.
Rubber vine is a Weed of National Significance and is regarded as one of the worst weeds in Australia because of its invasiveness, potential for spread, and economic and environmental impacts. Its main impact on pastoralism is the loss of grazing country, which in 1995 was estimated to cost the Queensland beef industry $18 million. It also increases the costs of mustering and fencing. Rubber vine has a potential distribution covering all of northern Queensland, the northern half of the Northern Territory, and most of the Kimberley region. The total area of rubber vine infestation in Queensland was estimated at over 700,000 hectares but was present in an area 50 times as large.
In the Kimberley there are three known locations, all of which have ongoing control programs attached to them.
More informationSalvinia (Salvinia molesta)
Legal status: Declared Pest. Prohibited s12.Presence in WA: Present.
Control / Keeping categories C2 - Eradication / Prohibited. Should be eradicated from part or all of Western Australia.
Salvinia is listed as a Weed of National Significance. It affects water quality and availability by creating a haven for mosquitoes, which are vectors of Ross River fever and encephalitis. Heavy weed cover also prevents the exchange of air that normally occurs on an open-water surface. High rates of transpiration through the leaves during summer can cause up to four times more water to be lost than is normally lost through water surface evaporation. The mats of weed also interfere with swimming and make fishing impossible. As native aquatic plants, birds and animals are displaced, the natural beauty of an open water body can be spoilt and further degraded. Under flood conditions, rafts of weed material build up at fences and bridges that, in turn, collect other floating debris. The combined weight may cause these structures to collapse. Water flow to irrigation equipment is reduced due to the restrictive action of the roots, which in turn increase pumping times and costs.
The plant has been found in Lily Creek Lagoon on the foreshores of Kununurra and in ponds around Broome. All infestations have been eradicated to date.
Sida (Sida acuta)
Legal status: Permitted - s11.Presence in WA: Present.
Control / Keeping categories. s11 for the whole of state and is not assigned to any control category for a local government area at this time.
An introduced species with a pantropic distribution, now naturalized in NT, and NEQ. Altitudinal range in northern Australia from near sea level to 500 m. Usually grows as a weed of agricultural land and waste places but also found in disturbed areas and along roads in rain forests.
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