Many environmental problems face us today. One of these is the spread of environmental weeds.
These notes list some of the invasive weeds of northern Victoria and southern (Riverina) NSW.
It is hope to add photographs of some locally-found invasive weeds.
Key to symbols:
N = noxious and notifiable weed (W1) in NSW ~ weeds marked (N) are noxious weeds in NSW, the presence of which on your land must, by law, be notified to the local authority (Central Murray County Council in NSW) and fully and continually suppressed and destroyedW2 = must be continually suppressed and destroyed in NSW
W3 = noxious weed which must be prevented from spreading and distribution reduced in NSW
W4 = noxious weed in NSW
P = State prohibited weed in Victoria
RP = Regionally Prohibited Weed in northern Victoria (i.e. not widespread but must be controlled by land owner/manager in northern Victoria)
RC = regionally controlled weed in northern Victoria (i.e. widespread but must be controlled).
Under construction: photos yet to be added
Weeds
of
Northern Victoria and Southern NSW
"From the Mimosa pigra threatening Kakadu to pasture grasses threatening fragile desert ecosystems and blackberries choking southern streams and alpine meadows, non-native species are running rampant after a century of unchecked growth. It's a silent invasion that is redrawing the Australian landscape."
~ Brad Collins,The Bulletin, 5th August 1997Weeds are plants that invade native vegetation, endangering the survival of indigenous flora and fauna, or unwanted plants that infest pastures, gardens or crops. In June 2005, the Australian Government announced a $40 million programme to attack weeds and asked State and Territory governments to ban the sale in nurseries of 20 listed 'weeds of national importance' (including Lantana, Rubber Vine, Bridal Creeper, Bitou Bush and Salvinia). The importation of about 3,300 potential weeds has been banned.
At the moment, plants which are regarded as noxious weeds in one State are sometimes still being sold in nurseries in other States.
Many roadsides and fields are covered by the purple flowers of Patersons Curse each spring. But there are many other, even worse, weeds. In fact, Australia has about 2,800 foreign weeds and a number of native weeds. About 10 new weeds are detected each year, many of them garden escapes.
Every piece of bushland, every farm, every pasture and every garden is subject to invasion by weeds. Tropical areas are sometimes hard hit. But weeds are found even arid and remote areas.
Ten of the worst
In the Echuca area, ten of the worst invasive weeds are:1 Paterson's Curse (Echium plantagineum) (W3, RC)
Introduced as a garden plant by the Paterson family, Paterson's Curse is common along local roadsides, on disturbed soils and on sandy loam. It can be spread by machinery. The weed has magneta-coloured flowers. The nectar is claimed by some to be carcinogenic.2 Arrowhead (Sagittaria graminea)
Arrowhead is a water weed that's fast spreading along channels, constricting water flow. An outbreak has occurred in the Barmah-Millewa wetlands. Arrowhead spells bad news for irrigators.3 African Boxthorn (Lycium ferosissimum) (RC, W2)
This prickly shrub which can form inpenetrable thickets and is very difficult to eradicate. Readily resprout if cut or burned.4 Cape Weed
Cape Weed is an invasive weed from South Africa. It is widespread, infesting vst areas. It has yellow flowers with many petals and a dark centre.5 Canary Island Palm (Phoenix canariensis)
Introduced as a garden ornamental, these palm trees are spreading into local bushland where they are very difficult to eradicate. Even small palms defy a whipper snipper and quickly develop a deep weed system so that hand weeding is not possible.6 Peppercorn (Schinus molle)
Being hardy, this tree was once widely planted on farms. Over the years, it has escaped into bushland. It harbours mosquitoes and drops duco-damaging gum on vehicles parked under it. Fortunately, most farmers are now landscaping with indigenous plants.
7 Gazenia
Despite the fact that they are spreading along roadsides and into bushland, Gazenias are, unfortunately, still sold and grown by some; invasive and hard to eradicate.8 Bridal Creeper (Myrsiphyllum asparagoides)
Bridal Creeper likes sandy and friable soils. It has invaded some areas of natural bushland, e.g. sandhills in Victoria Park Echuca. An insect is being introduced to help control it.
9 Parrot's Feather (Myriophyllum aquaticum)
In the same genus as Bridal Creeper, Parrot's Feather is a bright green freshwater herb which closely resembles our native Milfoil. It has the appearance of a tiny feathery conifer. It spreads from stem fragments, is invasive and difficult (impossible?) to control. Outcompeting Milfoil and other natives, it is rampant in the National Channel near Gunbower. Sterile plants appeared a few years ago at the headworks of Torrumbarry Weir and appear to have been spread by anglers and birds. In four years, this weed has spread from covering 4ha to over 120 hectares! It is likely to reach the Murray. It is in Campbells Creek and threatening the Loddon River. Despite being a weed of national significance, it can still be propagated and sold in Victoria because, despite being very similar to native Milfoil in appearance, it is a popular aquarium plant!!! A beetle eats the plant only to water level; biological control seems unlikely to be successful. Information to assist with the identification of Parrot's Feather can be found at Goulburn-Murray Water's web site.
10 Scotch Thistle (Onopordum spp) (W2)
A common weed alongside local waterways and irrigation channels. There are several other 'thistles' which are a nuisance locally.The Victorian Department of Conservation of Natural Resources has published an excellent booklet called Environmental Weed Invasions in Victoria. It lists an alarming number of environmental weeds, and outlines the dangers they pose.
Here is a list of some of the worst weeds and potential weeds in the southern Riverina and northern Victoria:
- African Boxthorn (Lycium ferosissimum) (RC, W2), prickly shrub which can form inpenetrable thickets and which is difficult to eradicate;
- African Daisy (Winged Groundsel), (Senecio pterophorus)(RP);
- African Feather Grass (Penniselum macrourum) (RP);
- African Lovegrass (Eragrostis curvula) (RP);
- Alligator Weed (Alternanthera philoxeroides) (N; P), a nasty aquatic weed which can clog waterways;
- Arrowhead (Sagittaria graminea), a nasty aquatic weed which can clog waterways;
- Artichoke Thistle (Cynara cardunculus) (RC);
- Basket Willow, undermines waterway banks, impedes water flow and outcompetes natives;
- Bathurst Burr (Xanthium spinosum) (W2, RC), vicious spikes injure stock and contaminate wool;
- Blackberry (Rubus fruticosus) (W2 RC), invasive, prickly shrub;
- Black Knapweed (Centaurea nigra) (N; P), prohibits germination of other species and not palatable to stock;
- Boneseed (Bitou Bush) (Chrysanthemoides monilifera) (P) (RP),
- Briar Rose (Rosa rubiginosa),
- Bridal Creeper (Myrsiphyllum asparagoides), invasive creeper in natural bushland;
- Broomrape (Orbanche spp) (N),
- Buffalo Burr (Solanum rostratum)( W3)
- Cabomba (Cabomba caroliniana) (noxious W4g in NSW), a nasty aquatic weed which restricts water flow;
- California Burr (Xanthium sp) (W2)
- California Thistle (Cirsium arvense) (RC),
- Caltrop (Tribulus terrestris) (RC),
- Camelthorn (Alhagi maurorum) (P),
- Canary Island Palm (Phoenix canariensis) (Canary islands), difficult to eradicate, harbours rodents and starlings;
- Cape Tulip (Moraea spp) (W2, RC);
- Cape Weed, an invasive weed from South Africa;
- Cherry Plum (Prunus cerasifera);
- Cockle Burr (Xanthium sp) (W2);
- Columbus Grass (Sorghum x alumum) (W2);
- Cootamundra Wattle (Acacia baileyana);
- Cotoneaster;
- Dense Water Weed (Egeria densa), a nasty aquatic weed which forms dense mats, restricting water flow;
- Devil's Claw (W3);
- Dodder (Cuscate campestris) (W2, RC), parasitic on trees, box-ironbark forest infestations seem worse following logging;
- Egeria ~ see Dense Water Weed;
- English Broom (Cytisus scoparius), a shrub which invades bushland even in alpine areas;
- Flatweed;
- Gazenia, still sold and grown by some; invasive and hard to eradicate;
- Golden Thistle (Scolymus hispanicus) (RC);
- Gorse (Ulex europaeus) (RC), invasive shrub with yellow pea-like flowers introduced as a garden hedge;
- Great Brome;
- Hardheads (Acropitolon repens) (W3, RC);
- Hawkweed (N);
- Hawthorn, an erect shrub which harbours feral animals;
- Horehound (W2, RC), herb which invades pastures and reserves;
- Horestail (N);
- Illyrian Thistle (RP);
- Ivy-leaf Sida (Malvella leprosa) (P);
- Johnson Grass (Sorghum halepense) (W2);
- Karoo Thorn (Acacia karroo) (N);
- Kochia (Kochia scoparia) (N);
- Lagarosiphon (Lagarosiphon major) (N, P), aggessive aquatic weed;
- Mesquite Bush (Prosopis spp) (N,P), six species of small tree/shrub, highly invasive;
- Mexican Feather Grass (Nassell nussima) (syn. Stipa tenuissima) (N);
- Miconia spp (N);
- Nodding Thistle (Carduuds nutans) (P);
- Noongoora Burr (Xanthium strumarium) (W2, RC);
- Onion Weed (W3);
- Parrots Feather (Myriophyllum aquaticum), a nasty aquatic herb which forms dense mats, similar in appearance to Milfoil;
- Parthenium Weed (Parthenium hysterophorus) (N,P), prolific seeder, causes dermatitis and asthma in some people;
- Paterson's Curse (Echium plantagineum) (W3, RC), can dominate roadsides and pasture, spread by seeds (e.g. in wheels of vehicles);
- Peppercorn (Schinus molle), a tree which harbours mosquitoes and drops duco-damaging gum on vehicles parked under it;
- Perrenail Ragweed (Ambrosia psilostachya) (P);
- Poverty Weed (Iva axillaris) (P), competes with cereal crops;
- Prairie Ground Cherry (W3, RC);
- Prickly Pear (Wheel Cactus) (Opuntia robusta) (RC) ~ fleshy stems with nasty spines; Prickly Pear is sometimes found in Box-Ironbark Forests (e.g. Kamarooka Forest and Wychitella NCR) but seems to be contained by an introduced grub, Cactoblastis;
- Ragwort (Senecio jacobaea) ~ toxic to stock;
- Rhus Tree (Toxicodendron succedaneum) (W2)
- Saint John's Wart (Hypericum perforatum) (W2, RC);
- Saffron Thistle (Carthamus lanatus);
- Salvinia (Salvinia nolesta) (N,P) ~ an aquatic fern which forms dense mats and reduces dissolved oxygen level, sterile but reproduces from fragments;
- Scotch Thistle (Onopordum spp) (W2);
- Senegal Tea Plant (Gymnocoronis spilanthoides) (N) ~ forms a mass of floating vegetation impeding water flows (unfortunately not declared in Victoria);
- Serrated Tussock (RV);
- Siam Weed (Chromolaena odorata) (N);
- Silverleaf Nightshade (Solanum elaeagnifolium) (W3, RC);
- Soursob (Oxalis pes-caprae);
- Spiny Rush (RC);
- Stemless Thistle;
- Spotted Knapweed (Centaurea maculosa) (N);
- Spear Thistle;
- Spiny Emex (Three-corner Jack) (Emex australis) (W3) ~ three-pronged burrs can inflict pain and puncture tyres;
- Spiny Rush (Juncus acutus);
- Sweet Pittosporum (Pittosporum undulatum) ~ native to eastern Australia, broader leaves than our indigenous Weeping Pittosporum which is not regarded as a weed;
- Tangled Hypericum (Hypericum triquetrifolium) (P);
- Tree of Heaven (Ailanthus altissima) (W2)
- Thorn Apples (Datura sp) (RC);
- Umbrella Sedge (Cyperus eragrostis) ~ perennial weed of roadside gutters and drains
- Water Hyacinth (N,P) ~ a nasty aquatic weed which clogs waterways;
- Water Lettuce (N);
- Willows (Salix spp) (noxious weeds W4g in NSW) ~ the sale of most species is banned in NSW and Victoria;
- Wild Garlic (RC),
- Wild Oats and
- Yellow Water-lily (Nymphaea mexicana) ~ has attractive flowers but can block waterways and make wetlands unsuitable for water birds.
Farmers would, no doubt, add lots of others.
A potential pest if introduced is Pride of Bolivia (Tipuana tipu), a tree with aggressive roots which spreads prolifically. Fortunately, it may still be absent from our district.
For details on actions required of land holders, see NSW Agriculture's Noxious Weed Site and Victoria's North Central CMA (03 5448 7124).
The Shire of Murray has trained 15 of its staff in the safe use of appropriate herbicides, and staff will use this knowledge to control and eliminate weeds from parks, gardens, lanes, drains, road shoulders, under signs, etc. In the Shire. The consideration of appropriate products has resulted in a preference for conservative, slower-acting and safer chemicals with a Nil Dangerous Goods Classification or the lowest Poison Schedule being selected. The Central Murray Country Council is in charge of noxious weed control in Murray Shire and intends to inspect properties within the Shire for noxious weeds.
Most weeds were deliberately introduced into this country. Of Australia's 18 worst environmental weeds, all but two were deliberately introduced as pasture/fodder grasses or as ornamentals. Some weeds are garden escapes. Even more were introduced as pasture grasses.
At least 60 of Australia's weeds originated at pasture grasses introduced into northern Australia between 1947 and 1985. Of these, 13 are now major pests. Ironically, the CSIRO recently came to the conclusion that many native grasses provide better fodder than introduced most grasses anyway! The sad fact is that we are still introducing into this country plants which are becoming major environmental weeds. Why?!
Introduced for cattle grazing, Gamba Grass is rapidly becoming the worst weed in northern Australia. This grass, if left uncontrolled, is likely to create monocultures of habitat throughout tropical Australia, proving unfit for a variety of woodland and grassland species as you mention below. Besides the natural environment, the impact of this grass would also be disastrous for the rural economy as well. Many bird species, including Gouldian Finch, Chestnut-backed Button-quail, and Yellow-rumped Mannikin face extinction if the grass spreads over their habitats.
Gamba Grass is highly inflammable. According to the chairman of the Gamba Action Group, David Welch, a large gamba grass-fuelled fire near Batchelor in 2004 spread five kilometres in 25 minutes.
In an article which appeared in Nature Australia in the Spring of 1995, Tim Low, an environmental consultant, claims that:
"It is a national scandal that so many of our worst weeds were deliberately brought in. We may wonder why governments did not act long ago to stop the damage. The sad truth is that vested interests in government and industry oppose a tightening of the quarantine net. Indeed, the Quarantine Service is hamstrung by funding cuts, and many of its functions have been privatised - which is like handing over the nation's defence to mercenaries."
We all should become involved in waging war on weeds. Many weeds are spreading rapidly, establishing dense thickets that choke out native plants and dependent native fauna. Many infestations appear beyond control by chemicals or biological agents. Wise use of fire may be one way of alleviating the problem. Apart from damaging the natural appearance of an environment, weeds cost Australia $3 billion dollars each year and represent one of the conservation problems of the twentieth century. About $6 million has been spent trying to rid Kakadu of Mimosa pigra. Goodness knows how many millions of dollars and thousands of man hours have been spent clearing and trying to control blackberries in the southern States.
Serrated Tussock is a weed that looks quite innocent but it has the ability to replace pasture species without the landholder knowing until it is too late. It is useless to stock and not even rabbits are interested in eating it! It has infested 24,000 hectares of the Rowsley Valley just north of Bacchus Marsh and could cover 4.6 million hectares within a few years unless it is controlled now! A million dollar offensive is now under way. The infestation has now spread east to the Hume Highway.
Some of the worst environmental weeds in Australia include Rubber Vine (which is smothering riverine forests in north Queensland), Lantana, African Boneseed, Japanese Knotweed (Horsetails), Paterson's Curse, Serrated Tussock, Blackberry, Gorse, Pond Apple, Salvinia, Bitou Bush, Willows, Prickly Pear, Mimosa and Bridal Creeper. The Australian Government has asked State and Territory governments to ban the sale of most of these weeds. Related to rhubarb, Japanese Knotweed comes from Mt Fuji where it tolerates cold temperatures and lava; its underground rhizomes can extend for up to 200 metres, allowing it to sprout on the far side of a road!
The worst weed-affected areas appear to be Cape York, the eastern seaboard (including the fringes of remaining tropical rain forests), the top end and Victoria.
Greg Keighery of the WA Dept. of Conservation and Land Management is quoted in the Bulletin as saying that "We can no longer assume the bush will be there forever, and in many ways it means we are losing our Australian identity".
Even today, some councils still plant species listed in the DSE book mentioned above as environmental weeds when they could use suitable indigenous species along roadsides and in public parks, e.g. Canary Island Palms are still being planted even though they are escaping into bushland.
It is possible to release insects to help control some weeds but some nursery interests are opposed to the release of insects which could attack some of the weedy plants currently on sale.
Some Australian plants have become "weeds" overseas. In parts of South Africa vast areas have been covered by Australian wattles, and in the Florida Everglades Melaleuca is rampant in places. Back in Australia, some of our weeds are native to other parts of our country, e.g. Cootamundra Wattle should be regarded as a weed in the Murray Valley.
Problematic aquatic weeds are threatening to choke local waterways.
In August 2005, Gunbower area residents concerned with the profusion of weeds in channels and in Gunbower Creek organised a field trip and public meeting to discuss the extent of the problem. The invasion of aquatic weeds is far worse than many thought and the situation is deteriorating.
An aquatic weeds expert with Goulburn Murray Water, Roger Baker, identified seven aquatic weeds which are of major concern:
- Alligator Weed (Alternanthera philoxeroides)
- Arrowhead (Sagittaria graminea)
- Fanwort (Cabomba caroliniana) (America)
- Dense Waterweed (Egeria densa)
- Parrots Feather (Myriophyllum aquaticum) (Amazon Basin, South America)
- Senegal Tea Plant (Gymnocoronis spilanthoides) (despite its name, native to Central and South America)
- Yellow Water-lily (Nyphaea mexicana) (despite the species name, native to Europe)
Not yet widespread in our district, Alligator Weed is found in Bendigo Creek. But it has the potential to move down the creek and into the Murray River. It is sometimes a free-floating mat. This highly invasive weed chokes waterways, removing oxygen and causing siltation. It is a prohibited weed in Victoria.
Arrowhead is an emergent aquatic herb which spreads by seed, rhizomes and tubers. It is a particular threat to lagoons and backwaters, preventing waders and water birds from feeding. Unfortunately, in Victoria it is still legal to propagate, transport and sell this invidious weed!!! Unless politicians act to ban its propagation, distribution and sale, the situation may worsen. Whilst it may be impossible to eliminate this weed, control measures are imperative if channels are to remain usable. The best method of control is to dig up and the plant and deposit it safely above high water level. In the Gunbower system, there are 38 sites downstream of the headworks, two of which are actively spreading. This weed is spreading at the alarming rate of 20km per annum! Information to assist with the identification of Arrowhead can be found at Goulburn-Murray Water's web site.
Cabomba (Fanwort) is a submerged aquatic herb which spreads easily and restricts water flows. Despite being a weed of national significance, it can still be propagated and sold in Victoria because it is a popular aquarium plant! There are infestations in Lake nagambie and lake Benalla. For more information on Cabomba, see Goulburn-Murray Water's web site.
Egeria is a submerged aquatic herb, usually rooted but sometimes floating. It forms dense mats which retard water flow. Only male plants appear to be wild, so no seeding takes place. But it is like the sorcerer's apprentice's broomstick, pieces breaking off to form new plants. Despite being banned in some States, it can still be propagated and sold in Victoria!!! Victoiran landholders may ring Goulburn Murray Water for more information about Egeria.
Parrot's Feather is a bright green freshwater herb which closely resembles our native Milfoil. It has the appearance of a tiny feathery conifer. It spreads from stem fragments, is invasive and difficult (impossible?) to control. Outcompeting Milfoil and other natives, it is rampant in the National Channel near Gunbower. Sterile plants appeared a few years ago at the headworks of Torrumbarry Weir and appear to have been spread by anglers and birds. In four years, this weed has spread from covering 4ha to over 120 hectares! It is likely to reach the Murray. It is in Campbells Creek and threatening the Loddon River. Despite being a weed of national significance, it can still be propagated and sold in Victoria because, despite being very similar to native Milfoil in appearance, it is a popular aquarium plant!!! A beetle eats the plant only to water level; biological control seems unlikely to be successful. Information to assist with the identification of Parrot's Feather can be found at Goulburn-Murray Water's web site.
Senegal Tea Plant is a hardy aquatic herb which forms a mass of tangled vegetation, covering the water surface. White florets cover the plants in spring-summer. It spreads by seeds and broken stem fragments. Water flow is impeded. There are infestationds in Lake nagambie and in te Goulburn River. Information to assist with the identification of Senegal Tea Plant can be found at Goulburn-Murray Water's web site.
Yellow Water-lily covers a lagoon along Matthews Road near Gunbower. Once a haven for waders and water birds, the lagoon can no longer sustain more than a handful of water birds, the weed covering the water surface and acting as a sediment collector. Consequent silting favours carp at the expense of indigenous fish. Victoiran landholders may ring Goulburn Murray Water for more information on Yellow Water-lily.
Other weeds damaging local waterways include Persicaria and Water Hyacinth (Eichlorina). Umbrella Sedge (Cyperus eragrostis) is a problem in many drains and roadside gutters. Weeds of streambanks and littorals include Basket Willow, Bridal Creeper, Olive Trees, Boxthorn, various thistles, various introduced grasses and burrs, Horehound and Sweet Pittosporum.
Other threats. Leaving water levels in wetlands for too long and at too high a level is causing many local wetlands to deteriorate. They need to be allowed to dry out occasionally and kept at a level low enough to avoid the under mining of bordering trees. Many trees have died because of inappropriate water management practices. During the field trip, participants were shown an example of a degraded wetland, Longmore's Lagoon. Water has been stored in the lagoon to meet the needs of 10 irrigation farmers. But the water has been kept at too high a level for too long and water flow has been restricted. Trees have died, trees have toppled down and blue-green algae has appeared in the stagnant water. Islands have disappeared and a a huge egret rookery has been all but abandoned by the birds.
After the field trip, participants met at the Gunbower Hotel to discuss steps which could be taken to control the deterioration of local waterways. It was resolved that local politicians be asked to ban the propagation, transport and sale of the above aquatic weeds. Unless action is taken, the cost of controlling aquatic weeds will escalate to the extent that water authorities may be unable to supply water to some irrigators.
A new weed management plan is being prepared for northern Victoria. Interested persons may attend a public meeting (date and venue unknown). Watch the local Press for details. Space restrictions and lack of photographs mean that few weeds are illustrted on this page. For photos, check out the web sites listed below.
A Co-operative Research Centre for Weed Management has been established.
The National Heritage Trust funds Weeds Australia. There is also information about weeds on the Goulburn Murray Water web site.
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