alert list for environmental weeds
Kochia – Bassia scoparia
Before eradication Potential Kochia (Bassia scoparia) The problem
Kochia is on the Alert List for Environmental Weeds, a list of 28 non- native plants that threaten biodiversity and cause other environmental damage. Although only in the early stages of establishment, these weeds have the
potential to seriously degrade Kochia Australia’s ecosystems.
Kochia was originally planted in 1990 for – Bassia scoparia forage and to rehabilitate salt-affected agricultural land in southwestern Western Australia. However, it soon spread out of control and was declared a weed in 1992. Plants die off during autumn and are blown by winds as tumbleweeds. Kochia is one of the fastest spreading Photo: R. Knox, WA Dept of Agriculture of all weeds in the United States. Because it is extremely efficient at using water, it but change to yellow, red and brown Key points thrives in warm, low rainfall environments as the plant ages and dies. The many flat, such as the cereal-growing regions of the elongated leaves grow up to 50 mm • Although originally planted for fodder and southern mainland states of Australia. long and 8 mm wide and have no stalk. to help rehabilitate saline soils, kochia quickly It can contaminate crops and suppress Leaves normally have three, but became weedy. the growth of nearby plants by releasing occasionally five, veins running along • Kochia seed can spread up to several kilometres chemicals into the soil. their length. carried on dead plants blown by the wind as tumbleweeds. Although palatable to stock, kochia The flowers are the same colour as the • Preventing its spread will protect the cereal crops may be toxic in large quantities. It can leaves. Flowers occur singly or in pairs, and pastures of much of temperate, semi-arid also alter fire regimes and reduce the in hairy spikes 5–10 mm long, along the and subhumid Australia. abundance of native plants. upper parts of the shoots where the leaf and stem join. The single seeds are dull • Eradication efforts seem to have been successful. The weed brown, 1.5 mm wide and contained in • Any new outbreaks should be reported to local a star-shaped fruit. Kochia has a main councils or state or territory weed management Kochia is a bushy annual, growing to taproot and a network of finer roots. agencies. Do not attempt control on your own. 1.5 m tall and wide in good conditions. Dead plants break off at the base and It has an erect main stem with many are blown by the wind as tumbleweeds. upwards-curving side branches. The stems and leaves are generally green, 2
Growth calendar 500 mm Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Flowering Seed formation Seed drop Dieback Germination
General growth pattern Growth pattern under suitable conditions Kochia is a bushy plant with an erect main stem Kochia is a summer growing annual. Most seed germinates in spring and early summer and numerous upwards-curving side branches. Photo: Jed Colquhoun, Oregon State University although, if conditions allow (late summer rains), seeds can also germinate from (USA) March to May. The seedlings grow vigorously, outcompeting perennial species with their rapid growth. Vegetative growth occurs for several months before flowering and seed production begin. Most flowering occurs between February and April, although Where it grows seedlings that germinate early or late in the season can flower at any time of the Kochia grows well under conditions year. Plants die shortly after the seeds are formed, with most plants dying between similar to those required by cereal crops March and May. Normally, the time between germination and death is six to seven in southern Australia, thriving in climates months. with hot, sunny summers. In the United States it is reported to grow in areas that receive as little as 150 mm annual although a small percentage of seeds How it spreads rainfall. It invades disturbed sites such may remain viable for two to four years. Kochia produces large numbers of seeds, as roadsides, railways and eroded banks, Kochia seed was deliberately planted in many falling close to the parent plant. and also grows in crops, pastures and southwestern Western Australia in 1990 rangelands. It tolerates saline soils and However, seeds can also be spread large to supply forage and help rehabilitate can flourish when irrigated with water distances from their original location salt-affected land. It was sown at 68 sites, of one-third the salinity of sea water. when the dead parent plant breaks off covering a distance of almost 1000 km. – Bassia scoparia at the base and is blown by the wind as Kochia is native to eastern Europe and By 1993 it had naturalised at 52 of these a tumbleweed. Kochia can spread up western Asia. It has been introduced as sites and spread to roadsides and pastures to several kilometres in a single year in an ornamental and become naturalised
Kochia and other areas not affected by salt. this way. Lines of seedlings indicate the throughout most of Europe, Argentina, path taken by the parent plants, which Kochia has also appeared in Tasmania Canada, United States, Africa, New often end up clumped near fences. on several occasions, introduced in Zealand and parts of temperate Asia contaminated carrot seed imported including China and Japan. The seeds are short lived. Most of the from the United States. seedbank is exhausted after one year, Why we need to be ‘alert’ to kochia
Although kochia was deliberately introduced, it was declared an eradicable weed only two years later. The decision to attempt eradication of kochia was based on its behaviour, including its: • very fast spread from the original plantings • invasion of crops and pastures and threat to agricultural production • invasion of areas where it was a nuisance (eg firebreaks, tracks, roadsides, fencelines) and potential Fences catch the tumbleweeds and can be sites of large infestations. to affect fire regimes and natural Photo: Steve Dewey, Utah State University (USA) ecosystems.
Weed Management Guide • Kochia – Bassia scoparia 3
Kochia gives itself a competitive Quarantine to prevent advantage by producing chemicals that further introductions reduce the growth and germination 15 mm Do not buy seeds via the internet or from of other more desirable plants, further mail order catalogues unless you check reducing agricultural production. with quarantine first and can be sure Additionally, kochia contains high that they are free of weeds like kochia. levels of oxalates, alkaloids and nitrates Call 1800 803 006 or see the Australian that can be toxic to a variety of grazing Quarantine and Inspection Service (AQIS) animals if large amounts are consumed. import conditions database Much of central and southern Australia
The Alert List for Environmental Weeds
The Federal Government’s Alert List for Environmental Weeds was declared in 2001. It consists of 28 weed species that currently have limited distributions but potentially could cause significant damage. The following weed species are therefore targeted for eradication:
Scientific name Common name Scientific name Common name Acacia catechu var. sundra cutch tree Koelreuteria elegans Chinese rain tree Acacia karroo Karroo thorn Lachenalia reflexa yellow soldier Asystasia gangetica ssp. micrantha Chinese violet Lagarosiphon major lagarosiphon Barleria prionitis barleria Nassella charruana lobed needle grass Bassia scoparia kochia Nassella hyalina cane needle grass Calluna vulgaris heather Pelargonium alchemilloides garden geranium Chromolaena odorata Siam weed Pereskia aculeata leaf cactus Cynoglossum creticum blue hound’s tongue Piptochaetium montevidense Uruguayan rice grass Cyperus teneristolon cyperus Praxelis clematidea praxelis Cytisus multiflorus white Spanish broom Retama raetam white weeping broom Dittrichia viscosa false yellowhead Senecio glastifolius holly leaved senecio Equisetum spp. horsetail species Thunbergia laurifolia laurel clock vine Gymnocoronis spilanthoides Senegal tea plant Tipuana tipu rosewood Hieracium aurantiacum orange hawkweed Trianoptiles solitaria subterranean cape sedge
Weed Management Guide • Kochia – Bassia scoparia 4
Weed control contacts
State / Department Phone Email Website Territory ACT Environment ACT (02) 6207 9777 [email protected] www.environment.act.gov.au NSW NSW Agriculture 1800 680 244 [email protected] www.agric.nsw.gov.au NT Dept of Infrastructure, Planning (08) 8999 5511 [email protected] www.nt.gov.au and Environment Qld Dept of Natural Resources and Mines (07) 3896 3111 [email protected] www.nrm.qld.gov.au SA Dept of Water, Land and (08) 8303 9500 [email protected] www.dwlbc.sa.gov.au Biodiversity Conservation Tas Dept of Primary Industries, 1300 368 550 [email protected] www.dpiwe.tas.gov.au Water and Environment Vic Dept of Primary Industries/Dept 136 186 [email protected] www.dpi.vic.gov.au of Sustainability and Environment www.dse.vic.gov.au WA Dept of Agriculture (08) 9368 3333 [email protected] www.agric.wa.gov.au
The above contacts can offer advice on weed control in your state or territory. If using herbicides always read the label and follow instructions carefully. Particular care should be taken when using herbicides near waterways because rainfall running off the land into waterways can carry herbicides with it. Permits from state or territory Environment Protection Authorities may be required if herbicides are to be sprayed on riverbanks.
Features to aid identification of kochia without their expert assistance. Control Ornamental form include: hairy flowers located at the top effort that is poorly performed or not Kochia exists in both a weedy and an of the stem where the leaf meets the followed up can actually help spread ornamental form. The ornamental form stem; star-shaped fruit and leaves with, the weed and worsen the problem. (Bassia scoparia forma trichophylla Kochia in most cases, three parallel veins along (hort. ex Voss)) is a different subspecies their length; and the tendency for the Herbicide tolerance to the weedy form (Bassia scoparia ssp. plants to break off at the base and roll – Bassia scoparia Overseas, kochia has shown that it can densiflora). The bright red autumn foliage as tumbleweeds when they die off become resistant to herbicides, which of the ornamental form is appreciated during autumn. means that plants survive treatment with by gardeners. It has been recorded as a herbicide that would normally kill them. a weed in South Australia and Western New infestations of kochia The resistance of kochia to two groups Australia and is a declared noxious Because there are relatively few kochia of herbicides, the sulfonylureas and weed in some states. Do not plant the infestations, and it can potentially be triazines, has been well documented in ornamental form of kochia, and replace eradicated before it becomes established, the United States and Canada. Herbicide any existing specimens with more any new outbreaks should be reported resistance is one of the reasons why kochia desirable species. Check with your local immediately to your state or territory was so quickly targeted for eradication. council or state or territory government weed management agency or local agency about the latest requirements council. Do not try to control kochia for controlling the ornamental form.
40 mm m
10 m
As the plant ages the stems, leaves and flowers Kochia stems are striped, and the leaves have virtually no stalk. turn from green to red to yellow to brown. Photo: Steve Dewey, Utah State University (USA) Photo: R. Knox, WA Dept of Agriculture
Weed Management Guide • Kochia – Bassia scoparia 5
Program to eradicate kochia from Western Australia...case is on track study
Both the biology of kochia and several infestation of thousands of plants was No kochia plants have been found since important aspects of the Western discovered in May 1996. This required 2000. Complete eradication of kochia has Australian infestation made eradication an additional significant control effort not been claimed, as a few plants were a realistic goal. These aspects include because it had been allowed to spread discovered at a site that had previously the following: uncontrolled for about five years. been clear for five years. If no more plants are discovered, the eradication program • kochia only reproduces by seed, which When control commenced, most of the will be judged as successful in 2005. is short lived infestations covered areas of less than • it is highly visible and flowers and seeds 10 ha, although a few were 100 ha or The eradication program was allocated are produced late in the season greater. Seedlings were present at virtually $200,000, with contributions from the • it is palatable to stock when lightly all sites that had contained mature plants Commonwealth Government and all of grazed in the previous autumn, often at very the states. Each state’s contribution was • the precise location of each of the high densities of several thousand per proportional to the value of its wheat original plantings was known square metre. industry, the sector most at risk from kochia. These funds were used to cover • the sites were easy to locate and The control program involved the use of operating and overhead costs, mainly the access herbicides, ‘crash’ grazing, grubbing and provision of herbicides. In-kind labour • many sites were well fenced, which flaming. Herbicides were delivered from contributions (eg monitoring and control reduced the distance tumbleweeds the ground and, for larger infestations, activities) throughout the project were could spread aerially. High densities of sheep were used estimated to be worth over $300,000. • control often commenced within 12 to provide extreme grazing pressure that months of the seed being sown caused defoliation of large plants and In addition to being well funded, the • there was no risk of reinfestation from destruction of seedlings. Grubbing, the program was well coordinated and elsewhere in Australia. physical removal of plants from the involved experienced agricultural officers ground, was also conducted where who had good local knowledge and The program began in early 1992 and appropriate. Flaming, where plants are productive relationships with affected
– Bassia scoparia had apparently achieved good results by burnt by a flamethrower or similar, was farmers. Farmers were consulted early early 1996. At this stage, kochia had been used on mature, seeding plants to kill in the program, were highly cooperative eliminated from 46 of the 52 known the seeds. and provided significant resources that Kochia caseinfestation sites; however, an unknownstudy assisted the eradication efforts.
The Tasmanian experience near Deloraine and Devonport have been Acknowledgments eradicated. Hand pulling was used to Kochia was found in Tasmania in 1995, remove all plants, which numbered less Information and guide revision: John 1997 and 1998, when seeds were than 50 in each of the infestations. Moore (WA Agriculture/Weeds CRC), discovered as a contaminant of imported Although some plants set seed at some John Dodd (WA Agriculture), Sandy carrot seed. Infestations in carrot crops sites, no seedlings were found, possibly Lloyd (WA Agriculture/Weeds CRC), Cindy Hanson (Tasmania DPIWE), Tony because of the herbicides used to control Grice (CSIRO/Weeds CRC) and John other weeds. The sites continue to be Thorpe (National Weeds Management monitored. Facilitator). Maps: Data used in the compilation of Legislation 15 mm actual and potential distribution maps provided by Australian herbaria via Kochia has been declared a weed across Australia’s Virtual Herbarium and the Australia except in the Northern Territory Australian Weeds Committee, respectively. and Victoria. Landholders are required The leaves and stems of kochia seedlings are particularly hairy. by law to control any declared weeds Photo: Steve Dewey, Utah State University (USA) occurring on their property.
Weed Management Guide • Kochia – Bassia scoparia Quick reference guide
Identification • single seeds, 1.5 mm wide, in a star- appropriate expertise and adequate shaped fruit resources. You will first need to confirm its • plants that break off and roll as identity. Contact your state or territory tumbleweeds when dead. Follow-up work will be weed management agency for help in required identifying the plant. You will need to Reporting occurrences take note of the characteristics of the Once the initial infestation is controlled, plant in order to accurately describe it. Once identified, new occurrences of follow-up monitoring and control will Some important features of kochia are: kochia should be reported to the relevant be required to ensure that reinfestation • stems, leaves and flowers that range state or territory weed management does not occur. in colour from green to yellow to red agency or local council, who will offer to brown as the plant ages advice and assistance on its control. • long, flat leaves with no stalk and three Because kochia spreads so quickly and parallel veins, occurring alternately poses such a serious threat, its control on the stem should be undertaken with the
Collecting specimens
– Bassia scoparia State or territory herbaria can also identify plants from good specimens. These organisations can provide advice on how to collect and preserve specimens.
Kochia State/Territory Postal Address Phone Web Australian National GPO Box 1600 (02) 6246 5108 www.anbg.gov.au/cpbr/herbarium/index.html Herbarium Canberra, ACT, 2601 National Herbarium Mrs Macquaries Rd (02) 9231 8111 www.rbgsyd.nsw.gov.au of New South Wales Sydney, NSW, 2000 National Herbarium Private Bag 2000 Birdwood Avenue (03) 9252 2300 www.rbg.vic.gov.au/biodiversity/herbarium.html of Victoria South Yarra, Vic, 3141 Northern Territory Herbarium PO Box 496 Palmerston, NT, 0831 (08) 8999 4516 http://www.nt.gov.au/ipe/pwcnt/ Queensland Herbarium c/- Brisbane Botanic Gardens (07) 3896 9326 www.env.qld.gov.au/environment/science/herbarium Mt Coot-tha Rd Toowong, Qld, 4066 South Australian Plant PO Box 2732 (08) 8222 9311 www.flora.sa.gov.au/index.html Biodiversity Centre Kent Town, SA, 5071 Tasmanian Herbarium Private Bag 4 Hobart, Tas, 7000 (03) 6226 2635 www.tmag.tas.gov.au/Herbarium/Herbarium2.htm Western Australian Locked Bag 104 (08) 9334 0500 http://science.calm.wa.gov.au/herbarium/ Herbarium Bentley DC, WA, 6983
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Disclaimer While every care is taken to ensure the accuracy of the information in this publication, the CRC for Australian Weed Management and the Commonwealth Department of the Environment and Heritage take no responsibility for its contents, nor for any loss, damage or consequence for any person or body relying on the information, or any error or omission in this publication.