| Weed Spotter Newsletter - Issue 45 |
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Welcome to the latest Weed Spotter newsletter.
In this issue we are reminded to keep on the look-out for Mexican feather grass, learn about new technology for detecting aquatic weeds, get the latest on online trade and learn from the recent large water hyacinth sites. Agriculture Victoria hopes you enjoy reading this issue of the Weed Spotter newsletter.
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| Reminder to Weed Spotters |
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✉️ Please remember that if you are moving to a new house or changing your employment, the contact details that Agriculture Victoria have recorded for you, including postal address and email address, may need updating. Please send an email to weed.spotters@agriculture.vic.gov.au to avoid missing the latest newsletter.
📅 Did you miss out on a copy of the 2026 State prohibited weeds wall calendar? If you didn’t receive one and would like a copy, please email weed.spotters@agriculture.vic.gov.au to opt in to the mailing list.
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| New to the Weed Spotters network? |
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Weed Spotters assist the Victorian Government by looking out for and reporting State prohibited weeds, which either do not occur in Victoria, or are present in small numbers and can reasonably be expected to be eradicated. These are a group of high-risk invasive plants that are declared under the Victorian Catchment and Land Protection Act 1994. More information about invasive plant classifications can be found here.
Agriculture Victoria is responsible for the eradication of State prohibited weeds. The Weed Spotters program is for those who work in an industry or who are part of a group where they are likely to spend time in places where State prohibited weeds could be found. To catch up on what you’ve missed, have a look at the Agriculture Victoria website to find past issues of this newsletter.
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| Mexican feather grass still on the loose |
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In the last twelve months, Agriculture Victoria has been alerted to three new Mexican feather grass (Nassella tenuissima) sites, demonstrating that the species is very much still one for Weed Spotters to be on the lookout for. Mexican feather grass flowers in Spring and Summer, when it is more likely to be spotted and distinguished from other similar looking grasses.
One of the new sites was spotted last November by a Weed Spotter who was dining at a Mornington Peninsula restaurant when they spotted what appeared to be Mexican feather grass growing in the restaurant gardens. They took some photos of the plants, including some close-up images of the feathery flowers, and made a report to Agriculture Victoria using the State prohibited weed online reporting form. Biosecurity Officers weren’t certain what the plant was initially, as the photos showed reddish seeds, instead of the usual creamy colour.
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Agriculture Victoria contacted the restaurant owner to explain the situation and arrange for an inspection. The owner had kept records of the plants purchased when the gardens were created in 2018, which identified the grass as Stipa lessingiana, a similar species not known to occur in Australia.
Image left: The mature Mexican feather grass plants growing in the garden.
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When Biosecurity Officers attended the restaurant and viewed the grasses, they found that the plants looked like Mexican feather grass in every way apart from the colour of the seeds. A sample of the whole plant including seed heads was taken to the National Herbarium of Victoria and formally identified by botanists as Mexican feather grass.
Image right: A close up of the seeds with their reddish tinge.
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Five mature plants and over 100 seedlings were removed by hand and carefully spot sprayed throughout the gardens. There was a large amount of seed present, and not all was able to be removed, as it was stuck between cracks in the path, and in difficult to reach places. Follow up will occur over the coming years to remove seedlings that germinate and ensure Mexican feather grass is eradicated from this site.
Thanks to the great record keeping of the owner, Agriculture Victoria was able to follow up with the nursery who inadvertently sold Mexican feather grass as Stipa lessingiana and tracing is underway to determine if there are any more planted in gardens across Victoria.
Image below: Some of the Mexican feather grass seedlings that popped up in locations around the garden.
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If you would like to know more about Mexican feather grass, please have a look at the Agriculture Victoria website here. If you think you have seen Mexican feather grass anywhere in Victoria, please report it by sending an email to weed.spotters@agriculture.vic.gov.au or complete the reporting form here.
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| A new approach for detecting State prohibited weeds using environmental eDNA |
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Can you detect State prohibited weeds without seeing them? Or know if they were present after they’re gone? The short answer is YES!
All living things contain and shed DNA into the environment. Like clues left at a crime scene, invasive weeds leave their genetic material or DNA in their environment, which can include water, faeces, soil and air.
When a sample is taken from an environment, and DNA is extracted and analysed, this process is known as environmental DNA (eDNA). The technique is yet to be adopted for weeds in Victoria; however, Agriculture Victoria’s marine pests program uses eDNA to detect invasive species and regularly monitors for a range of high-risk species, including exotic sea squirts, mussels and crabs.
The New South Wales Department of Primary Industries and Regional Development (DPIRD) has recently investigated eDNA applications for aquatic weeds in Australia. The research focuses on a variety of species, including two Victorian State prohibited weeds: alligator weed (Alternanthera philoxeroides) and water hyacinth (Eichhornia crassipes).
A federally funded project through the Department of Agriculture, Fisheries and Forestry, is trialling eDNA technology in NSW, QLD, WA and Victoria. Given Australia’s wide-ranging environmental conditions, the method is being tested across different waterways (such as closed water bodies and flowing streams) and climates (from temperate to tropical). Three Victorian locations have been selected for the trials, and Agriculture Victoria has volunteered to collect water samples from known infestations and nearby waterbodies. The aim is for the eDNA collected to indicate the extent of the infestation and provide valuable data for the trial.
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In preparation for sample collection, DPIRD conducted training at Agriculture Victoria’s Attwood office for staff and other agencies involved in the trials. Two methods of sample collection were demonstrated and practised during the training:
1. The Smith-Root Citizen Science Sampler: This method uses a battery pump to push water through a fine filter, collecting eDNA for later analysis. It is quick and easy to use and requires little handling during sample collection.
2. The QuickConc: This method is lighter and does not use electronic parts. It uses a small portion of glass fibre and buffer to extract and bind the eDNA for collection as the water drains through a filter. Although slower, it is ideal for remote locations when travelling light may be necessary.
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Image above: Agriculture Victoria staff learning how to take eDNA water samples.
DPIRD is testing for eDNA over time and distance. Samples taken downstream, further from the infestation location produce a weaker signal as the eDNA becomes diluted. Similarly, after a weed is treated, the DNA breaks down, and the signals weaken over time. Current findings suggest that eDNA may remain detectable in a waterway for 18-24 months after a plant has been removed, and can be reliably detected up to 1000m downstream. This opens up new opportunities for detecting State prohibited weeds, once species-specific tests are available.
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Agriculture Victoria could consider using the technology to set up sentinel testing sites regularly monitoring for new incursions of State prohibited weeds, before the plants have been observed and reported. Alternatively, eDNA sampling can help determine the extent and location of new infestations, by testing adjacent or nearby waterways, eliminating the need to inspect the entire area. This sensitive and rapid method will save hours of manual surveying, particularly in heavily vegetated, inaccessible, remote or large areas. Samples can also be tested for multiple species, enabling detection of several high-priority weeds in one sample.
Image left: eDNA techniques could be utilised to look for new water hyacinth and alligator weed infestations in Victoria.
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Agriculture Victoria looks forward to contributing samples for the trial and collaborating with DPIRD on future eDNA trials. To learn more about DPIRDs work, refer to the references below.
References:
1. Zhu, X.; Bell, K.L.; Wu, H.; Gopurenko, D. Development of an Environmental DNA Assay for Prohibited Matter Weed Amazon Frogbit (Limnobium laevigatum). Environments 2024, 11, 66
2. Zhu, Xiaocheng and Bell, Karen L. and Wu, Hanwen and Gopurenko, David, An Issue of Life or Death: A Qpcr-Based Environmental Rna (Erna) Approach Might Not Be Suitable for Aquatic Weed Biosecurity
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| Plants continue to pop up online |
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Unfortunately, the online trade of State prohibited weeds is still going strong. Agriculture Victoria has detected 20 illegal online sales of State prohibited weeds since July 2025 from locations across Victoria, New South Wales, Queensland and the ACT. Ten of these were in Victoria, an increase from only 6 detected in the State in 2024/25.
Online trade of State prohibited weeds allows plants to be spread quickly and easily over large distances, even between states, which could mean disaster for waterways, agriculture and the environment. Weed Spotters have made a valuable contribution to these reports, thanks to the many people keeping a look out on online social and selling platforms - this is Weed Spotting you can do from the comfort of your own home! One recent water hyacinth report that was detected during the Australia Day long weekend was reported by 5 separate Weed Spotters. It is great to know that so many people are on the lookout!
Agriculture Victoria investigates all detections in Victoria, seizing plants and disposing of them safely. This season, 7 water hyacinth (Eichhornia crassipes), 1 horsetails (Equisetum species) and 2 alligator weed (Alternanthera philoxeroides) for sale posts have been found. Detections from other states are passed on to the relevant jurisdictions, who follow up these reports in a similar way.
The detections that have been picked up this season have all been found on Facebook marketplace or through Facebook community pages.
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Biosecurity Officers searching for State prohibited weeds in online trade find using the terms ‘water plants’, ‘aquatic plants’ or ‘pond plants’ most often result in successful detections. Officers also search for the species names, both common and botanical, and in the case of alligator weed search for the edible plants ‘ponnaganni’ or ‘mukunu wenna’ that can be misidentified alligator weed.
Image right: One of the online sale posts found on Facebook Marketplace.
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Agriculture Victoria also educates the public and raises awareness of State prohibited weeds through social media pages on Facebook. With this public education, as well as Weed Spotters on the case, we are hoping that very few illegal online sales will escape undetected both in Victoria and across Australia.
If you see an advertisement for a State prohibited weed for sale, please take a screenshot containing all information including the photos and the seller, and email it to weed.spotters@agriculture.vic.gov.au, submit it to the State prohibited weed online reporting form or call the Customer Contact Centre on 136 186. It is very important that Weed Spotters don’t tell the seller that they shouldn’t be selling the plant. Otherwise, the seller may remove the post before Agriculture Victoria can contact the seller, safely remove the plants and avoid the risk of the plants spreading further.
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| Learning from water hyacinth infestations |
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You might remember the Spring Weed Spotter newsletter looked at water hyacinth infestations found in waterways over the last five years. Since 2020, 59 new infestations of water hyacinth have been found in total with most cases (50) located in small, residential ponds and 9 occurring in waterways. The size of the waterway cases have been trending larger over time, with the most recent being 5000m2. The larger these infestations become, the more difficult, costly and time consuming they are to treat. Refer to the Spring newsletter if you would like to read more.
The impacts and consequences of water hyacinth waterway infestations are significant, interfering with:
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agricultural use: stock access, clogging up pumps and drains,
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recreational uses: blocking fishing, boating, and changing the habitat to support different types of fish and sometimes causing fishkills,
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environmental values: displacing native plants, and altering habitat for native fauna, altering wetland function and ecosystem services,
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health: increasing habitat and sustaining larger populations of mosquitoes (vectors for blood-borne diseases),
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economic impacts, either in treatment costs or losses incurred from other impacts.
A review has been completed to help inform how Agriculture Victoria continues to manage this species for eradication:
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How does Agriculture Victoria detect water hyacinth in open waterways? Most commonly, they are reported by the landowner or a Weed Spotter!
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When does Agriculture Victoria detect water hyacinth in open waterways? Detections can occur at any time of year, although summer is the most common.
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Where do we find water hyacinth in open waterways? Most commonly in peri-urban areas, although also in metropolitan suburbs and rural areas (see graph below).
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What types of waterways contained new water hyacinth infestations? Most commonly garden ponds, but occasionally drains, farm dams and wetlands (see graph below).
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How big are the infestations when we find them? More than half the time, the infestation is smothering the water body (at 75-100% cover), a quarter of the time its partially covering the water body, and occasionally it is a very young infestation with only a few plants.
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How did the plants get there in the first place? Humans are the most common way plants are spread, it may involve accidentally bringing in seed or buying a plant for their pond, but humans are almost always the vector.
Image below: Map of open waterway cases found between 2020-2025: total 9 cases.
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| Species profile – Camel thorn |
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Camel thorn (Alhagi maurorum) is a State prohibited weed that is found in the northern parts of Victoria, usually associated with irrigated pastures along drainage lines and neglected areas. It is unclear how camel thorn was initially introduced to Australia, though it was recorded at Rutherglen in 1915. Isolated infestations have also been found in New South Wales, South Australia and Western Australia. The native range of camel thorn spans across eastern Europe, the Middle East and Central Asia.
Camel thorn has a vigorous root system that can penetrate to over 2m deep, making it strongly competitive with other plants.
Image left: A camel thorn plant growing along an irrigation channel.
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It has lateral roots that can grow up to 8m each year from the parent plant. Camel thorn roots are so strong that they have been known to break through sealed bitumen roads and the plants’ sharp-tipped spines can be a danger to livestock.
Image right: Camel thorn plant growing through a bitumen road.
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The species primarily spreads by the root fragments being moved during crop cultivation. It poses a serious risk in Victoria as it can compete with and eliminate other vegetation including farm crops, preferred forage plants for livestock and native plants.
Camel thorn is a rigid, much-branched, spiny shrub that grows up to 1.5m tall. The above ground growth dies off in autumn, and the plant stays alive underground via the extensive root system. New shoots emerge from these roots in spring.
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• Leaves - Oval or arrowhead shaped with smooth edges and blue-green in colour.
• Spines - Numerous, yellow-tipped that grow on the stems.
Image left and below: camel thorn leaves, spines and flowers.
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• Flowers - Pea-like, pink-purple to yellow-brown and grown in small loose clusters of 1-8 during spring and summer.
• Seed pods - Red-brown (8-28 mm long) containing 1-5 smooth, red-brown, kidney shaped seeds that grow to 3 mm.
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• Growth - active growth occurs between October and March. Flowering occurs from November to March.
Image left: Camel thorn grows as a small shrub.
If you think that you may have seen camel thorn then please report it to Weed Spotters via the online form or send an email to weed.spotters@agriculture.vic.gov.au.
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| Weed Spotter training at your fingertips |
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Did you know that Weed Spotter training is available to Weed Spotters at any time?
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The online training module mirrors, and was created from, the face-to-face format and materials. It includes photos and videos of State prohibited weeds so that Weed Spotters can become more familiar with these plants. It also describes how to report a State prohibited weed and has interactive quizzes and exercises to help you learn.
The course can be paused and recommenced at any time, without losing your place. All Weed Spotters who complete Weed Spotter training receive a set of State prohibited weed identification cards.
Image left: All Weed Spotters receive a set of State prohibited weed cards after completing the online Weed Spotter training module.
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Recent trainees have said:
“The Weed Spotter training was really useful and well set out, I enjoyed completing it.”
“I thought the online training was really good. It didn’t take too long to complete, and the content was meaningful and provided a good introduction to the main issues for Weed Spotters to be aware of.”
“Loved the course!”
“It was a pleasure and very enlightening.”
“Thank you for providing access to the Weed Spotter training – I thought the course was terrific. It was clear, informative, and easy to follow.”
“I look forward to spruiking the online training to our local volunteer groups, it is very well set up.”
How to access the training:
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To access the training please go to eLearning section of the Agriculture Victoria website and create a log in for the site by clicking ‘sign up’.
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When creating a new account, make sure you select ‘I am a Weed Spotter’ in the ‘Why are you here?’ drop down menu.
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Once you have created an account, you can select Weed Spotter training.
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Make sure that you navigate right to the end of the training so that it triggers the completion notification.
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You will then be posted a set of State prohibited weed cards.
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Weed Spotters can also download an attendance certificate at the end of the training if they wish.
Image below: The online Weed Spotter training module.
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