DEPARTMENT OF ENVIRONMENT AND NATURAL RESOURCES Rapid response to the inadvertent sale and propagation of sagittaria (Sagittaria platyphylla), an aquatic Weed of National Significance Louis Elliott and Roni Opden, Weed Management Branch, PO Box 496, Palmerston NT 081, Australia, email: [email protected] Summary The Response Sagittaria (Sagittaria platyphylla) is an recovered. In addition, two historical 1. Detection aquatic Weed of National Significance pond plantings were discovered and • An off-duty NT Government Officer and a declared Class A weed in the controlled. detected sagittaria for sale in Bunnings Northern Territory. Surveys of surrounding land and native in mid-2016, labelled Melon Sword (Echinodorus osiris). In 2016 it was misidentified, waterways failed to detect any wild mislabelled, propagated and sold by a populations. • Bunnings immediately removed the commercial plant wholesale nursery plants from sale, but 27 had already The incident demonstrated the been sold to the general public. which triggered a rapid response with importance of correctly identifying the aim to eradicate it in the Top End. • Weed Management Officers seized 109 and labelling plants prior to potted plants from the commercial plant During the highly successful response, propagation and sale, and the vital wholesaler, and all remaining plants 109 potted plants were seized and role that government agencies play in from Bunnings. Photo: Sagittaria for sale labelled Melon Sword. destroyed prior to sale. Of the 28 reducing the risk of weedy garden and • Several plants were also found at Mitre 10 in Katherine, WEED ALERT plants sold to the public prior to pond plants spreading into the natural of which one had been sold. Sagittaria platyphylla detection, 23 plants have been environment. DARWIN AND RURAL AREA ) has been found in the Darwin area. Sagittaria Sagittaria( platypylla 2. Media campaign and recall This is the first known occurrence of sagittaria in the Northern Territory. Sagittaria is a Class C (not to be introduced into the Northern Territory) weed and is a Weed of National Significance. Sagittaria can have serious impacts on the natural environment, and in particular on wet- • An intense media campaign commenced, alerting the general lands and in drainage channels. What is the problem? Sagittaria is a highly invasive aquatic weed that can: public to report and return any sagittaria purchased. • form dense monocultures in water to 1 m deep • choke wetlands and waterways • adversely affect aquatic biodiversity • Sagittaria (Sagittaria platyphylla), • impact on aquatic recreational activities • Many plants were reported and returned. One of these reports was • reduce the visual amenity of waterways also known as arrowhead, is an • produce up to 20 000 seeds a pond that was planted with sagittaria (more than 10 years old). Plants were discovered and ornamental aquatic plant that found to be sold at both Darwin and Palmerston Bunnings. These plants were can invade waterways and native • The pond discovery triggered a rapid response. misidentified on the label as: Aquarium Plant Melon Sword vegetation. (Echinodorus osiris) • First reported naturalised in 1959 3. Rapid response near Brisbane and spread rapidly • Searching of residential blocks within 500 m of the historic pond If you have seen this plant or bought one from Bunnings, please contact in the 1970s in Victoria, New detected a second pond cultivated for 17 years. NTthe News, Weed Friday, Management September Branch 23, 2016, immediately pages from on 7 to8999 7 4567. Page 1 of 1 DO NOT DISPOSE OF THIS PLANT YOURSELF South Wales and Queensland. NT News, Friday, September 23, 2016, pages from 1 to 1 • Extensive surveys of surrounding wetlands and potential habitat Photo: Sagittaria flyer Page • Chokes wetlands and waterways within 2.5 km of pond failed to distrubted to the public. 1 of 1 and restricts waterflow, adversely detect any wild populations. impacting biodiversity and • A compliance investigation recreational activities such as was undertaken into the sale boating and fishing. Photo: Sagittaria infestation, Victoria (Raelene Kwong, DEDJTR). of a declared weed under the • Prolific seeder, producing up to Weeds Management Act. 20,000 seeds per plant and can also spread through stolons and tubers. • Spread by humans as an ornamental plant and can be accidentally spread from ponds 4. Outcomes into native waterways. • The public recall raised community awareness, prompted the reporting • Early detection is critical to successful control because sagittaria is difficult to control of purchased plants and the with herbicides. discovery of two historic pond plantings, both of which have been How to distinguish sagittaria from other plants controlled. • To date, 23 sagittaria plants have • Aquatic herb. been recovered, out of the 28 sold to • Flowers with 3 white petals and yellow stamens. the public. Photo: Media coverage in the NT News. • Leaf form is variable with different submerged and emergent forms. • The plant wholesaler was fined for • Emergent leaves have stems that are triangular in cross section. selling declared weeds to the retailers. http://enews.smedia.com.au/ntnews/PrintPages.aspx?doc=NCNTN/2016/09/23&from ... 23/09/2016 • Easily confused with sword plants (Echinodorus spp.) which are commonly cultivated in http://enews.smedia.com.au/ntnews/PrintPages.aspx?doc=NCNTN/2016/09/23&from • The risk of spread to the natural environment of a new weed has been significantly reduced.... pots and ponds. 23/09/2016 • Definitive method of distinguishing them requires flowers – sagittaria has separate 5. What went wrong? male and female flowers, while sword plants have only one type of flower (with male and female parts). • Potting up an unknown plant with weedy characteristics – not a good idea. • Sagittaria can also be confused with other sagittaria species. The most common is • Not getting accurate identification prior to sale. ‘arrowhead’ (Sagittaria sagittifolia) which is also cultivated and traded. Arrowhead • Plant labelled with a wrong name. (Sagittaria sagittifolia) can easily be distinguished from sagittaria (Sagittaria platyphylla) • Biosecurity checks were then conducted on the wrong name and did therefore not pick up the error. byDEPARTMENT the long OF lobes on the leaves which resemble the barbs of an arrowhead. ENVIRONMENT AND NATURAL RESOURCES • Nursery Industry Best Management Plant Labelling Guidelines are voluntary and not binding. Sagittaria is declared a Class A (to be eradicated) and Class C (not to be introduced) weed in the Northern Sagittaria Territory and is a Weed of National Significance in Australia. We still need your help Sagittaria is a declared weed in accordance with the Weeds Management Act. Sagittaria platyphylla Although the recall and response from the general public has been successful, there HABIT STEMS & BRANCHES LEAVES FLOWERS REPRODUCTION may be up to five more mature sagittaria plants that were sold from Bunnings and Katherine Mitre 10 in 2016 still growing in gardens. We still need your help to locate them as well as any older plantings that may have gone undetected. If you see a plant Sagittaria is a fast growing, The stems of sagittaria Sagittaria has two The small white, or Fruit is produced in a cluster perennial aquatic plant. are spongy and triangular- different types of leaves. sometimes pink flowers of one-seeded segments. that might be sagittaria, report it to the Weed Management Branch on 08 8999 4567. It grows rooted in the ground shaped in cross-section. The emergent leaves are have three petals around a Each segment is flattened and can be fully submerged lance-shaped, up to 28cm yellow centre. They appear and winged and about 1.5 to or its leaves can emerge long and 10cm wide, on a at the top of a leafless 3mm long. above the water surface. long stalk. stalk, always below the leaf height. It can grow up to 1.2m tall. The submerged leaves are translucent and strap- Further information like, up to 50cm long. weeds.ala.org.au/WoNS/sagittaria Weed Management Officers from the Weed Management Branch can provide advice on all aspects of weed management including control techniques, biological control, legislative responsibilities, policy advice, monitoring and reporting and regional planning. For further information on weed management planning, integrated control, herbicide application techniques and monitoring please refer to the NT Weed Management Handbook. www.nt.gov.au/sagittaria T: 08 8999 4567 E: [email protected] W: www.nt.gov.au/weeds References Acknowledgements Adair, R., Keener, B., Kwong, R., Sagliocco, J. & Flower, G. (2012). The Biology of Australian weeds 60. Sagittaria platyphylla (Engelmann) JG Smith and Sagittaria calycina Engelmann. Plant Protection Quarterly 27: 47-58. The Weed Management Branch would like to thank everyone who has reported suspected sagittaria plants during 2016–2017. The recall was extremely successful due to the high level of support from the general public. We would also like to particularly thank people that had sagittaria Australian Weeds Committee (2012). Weeds of National Significance, Sagittaria (Sagittaria platyphylla) Strategic Plan. Australian Weeds Committee, Canberra. in their ponds for their support and help with its eradication. Petroeschevsky, A. (2012). Weed Management Guide – Sagittaria, Australian Government, Canberra..