Welcome to the latest Weed Spotter newsletter. In this issue we find out about new discoveries of horsetails, Mexican feather grass and water hyacinth, all thanks to Weed Spotters passing on these valuable reports. We also look at the differences between Mexican feather grass and a close cousin serrated tussock and find out how online trade detections are tracking this year.

If you have any feedback on this edition or suggestions for future articles, please email: weed.spotters@agriculture.vic.gov.au.

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 Invasive Plants Classifications under the Catchment and Land Protection Act 1994. 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.

In July 2021, a Weed Spotter reported a horsetail (Equisetum spp.) infestation growing in a front yard in Melbourne’s south-east. Agriculture Victoria officers inspected the property and confirmed it as the tall growing horsetail species Equisetum hyemale (often called ‘scouring rush’).

The horsetail was growing densely throughout the front yard, with some shoots emerging through cracks in the asphalt footpath outside the front of the property and there were a few shoots seen to be emerging in the next-door property’s front garden, having grown under the side fence.

Left unchecked, horsetail infestations such as this can spread to form a large and continuous infestation, spanning multiple properties, with the shoots connected underground by rhizomes that have passed underneath fences, paths and other obstacles.

Subsequent spread to other areas can then be initiated by any activity that fragments the rhizomes such as digging and moving affected soil, inappropriate disposal of weeded-out plants and rhizomes or by water dispersal of soil and plant fragments to other areas.

However, it is possible an occasional shoot may still emerge and require treating over the coming years. The site will therefore be monitored by Agriculture Victoria for years to come, until we are confident that eradication has been achieved and that no more shoots will re-emerge.

Discussions with the landowner revealed that the horsetails were originally purchased and planted in the front garden ‘about 20 years ago’.

Being a front-yard infestation that has been there for many years, and because it can be easily spotted by a passer-by from the street, it is surprising that this infestation has not been detected and reported earlier than this.

It just goes to show that even with Weed Spotters’ best efforts and successes with detections over the years, there are obviously still some streets in Victoria that have not yet been walked by Weed Spotters. It’s always worth looking into gardens as you walk along the streets. You never know what you may find!

Last month, Biosecurity Officer and Weed Spotter, Brian Howlett stumbled across an infestation of the State prohibited weed Mexican feather grass (MFG) on a private property in Ararat, while out training on his bike. MFG is a serious weed to Australia as it is hardy, drought tolerant, unpalatable to stock and difficult to control.

It is estimated that anywhere from 14 million to several 100 million hectares of Australian land could be vulnerable to Mexican feather grass infestation - this could exceed the extent of the closely related serrated tussock, widely regarded as Australia’s worst pasture weed.

In 2008, MFG was inadvertently sold by several retail chain stores throughout Victoria. Investigations have revealed that approximately 4,000 plants may have been supplied to stores and a large-scale response was undertaken at the time to track down as many plants as possible.

Thousands of MFG plants were recovered from approximately 500 sites across Victoria. Biosecurity Officers are still actively managing 176 of these sites until they are considered eradicated.

Ongoing surveillance and a proactive media campaign in the local area is now underway to find any other undetected infestations.

If you think you may have seen MFG, or you are wondering how to identify it, check out the next article!

Agriculture Victoria regularly receives reports of suspected MFG plants, which upon inspection, are found to be serrated tussock. Serrated tussock is classified as a Regionally prohibited weed or a Regionally controlled weed under the Catchment and Land Protection Act 1994 depending on where in the state it is located, and it is the landholder’s responsibility to manage weeds in these categories.

Both grasses grow in tussocks and have tightly rolled leaves that roll between the fingers like a pin. Leaves of both species feel coarse when sliding fingers down the leaf blade towards the base of the plant. However, there are differences between the two species.

To assist Weed Spotters to distinguish between these two species, the following comparison table has been created. The best way to distinguish between the two plants is by looking at the flowering stems and seed heads. If the plants are not in flower, identification can be more difficult.

If you think you may have seen MFG, please email weed.spotters@agriculture.vic.gov.au or call the Customer Contact Centre on 136 186.

References
Mexican feather grass seed image: Grasses of New South Wales (Fourth edition) S.W.L. Jacobs, R.D.B Whalley, D.J.B. Wheeler, University of New England, Armidale Australia 2008”

Serrated tussock seed image: https://vicflora.rbg.vic.gov.au/flora/taxon/5a69fe1d-8641-4d6c-b526-f43d8b09fd33#&gid=1&pid=5

A diligent gardener has responded perfectly after coming into possession of the State prohibited weed, water hyacinth.

One day, while strolling through a local park, the gardener was given some ‘surplus’ water hyacinth from another park-goer. She took the plants home, placed them in buckets, and researched what they were.

After a short internet search, she found out she had a highly invasive weed and she reported it immediately to Agriculture Victoria. She also locked the buckets in an outdoor hutch, to ensure they wouldn’t accidentally escape off her property or into her pond.

Biosecurity Officers arrived on the scene and were very impressed with her responsive actions to report and contain the water hyacinth. While it is an offence to transport, plant or propagate, and even display State prohibited weeds in Victoria, no charges were pursued given the gardener’s earnest effort to protect Victoria’s biosecurity and have the weed eradicated.

Her swift actions also led to a quick eradication the following season. If she had not been so diligent, and the water hyacinth had been placed in her pond, it may have flowered and deposited thousands of seeds, resulting in a seedbank which requires a lengthy period of monitoring. Water hyacinth seeds remain viable for up to 30 years and there is a risk of water hyacinth re-emerging before that period has passed.

This report is really encouraging for Agriculture Victoria as we can be confident that unaware gardeners can easily find clear information about water hyacinth and what to do if they see it. Fortunately, water hyacinth is a highly distinctive floating plant, even without flowers, making it easy for gardeners to identify. In particular, the bulbous, spongy stems and paddle-shaped leaves floating on the water surface, help them stand out.

Unfortunately, Agriculture Victoria is yet to find the generous park-goer who provided the water hyacinth and we encourage residents of the Swan Hill and Kerang areas to come forward if they have water hyacinth, and to keep an eye out for water hyacinth in garden ponds and dams.

Unfortunately, the online trade of State prohibited weeds (SPWs) is still going strong. Agriculture Victoria has detected 48 illegal online sales of SPWs this financial year from locations across Victoria, New South Wales and the ACT. This is a 12 per cent  increase compared to the same period last year where 43 sales were detected.

Online trade of SPWs 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!

Agriculture Victoria investigates all Victorian detections and have seized 305 water hyacinth (Eichhornia crassipes) plants since the beginning of January. All the seized plants were disposed of safely. Reports from other states were passed on to the relevant jurisdictions, who follow up these reports in a similar way.

The reporters have spotted a photo of water hyacinth and recognised the distinctive features of the plant, or they have noticed the seller using the name ‘water hyacinth’.

Some of the plants that have been seized during January have been found because of tracing activities which involves interviewing the seller and finding out where they originally obtained the plants and whether they have passed them onto anyone. This is a very important step in any investigation.

Agriculture Victoria also educates the public and raises awareness of SPWs through various social media platforms like Facebook and Twitter. 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 SPW for sale, please take a screenshot and email it to weed.spotters@agriculture.vic.gov.au, or call the Customer Contact Centre on 136 186.

Agriculture Victoria is encouraging Weed Spotters to keep a look-out for the highly invasive State prohibited weed, orange hawkweed and to report any suspect plants. There are orange hawkweed sites currently being monitored and treated by Agriculture Victoria at sites at Blackwood, Daylesford, Mount Macedon, Trentham, Mount Buller and Falls Creek, so Weed Spotters should keep a look out in these areas in particular.

Native to Europe, hawkweeds have the potential to cause significant impact to native ecosystems through restricting the growth of neighbouring plants by releasing chemicals into the soil and replacing native plants with a dense mat of rosettes. Hawkweeds can spread quickly by seeds that are carried in the wind, from above-ground runners (stolons) or by root fragments.

If an infestation of hawkweed is found anywhere in Victoria, Agriculture Victoria will treat, remove, and dispose of the plants at no cost to the landowner.

If you think you have seen orange hawkweed, please do not attempt to treat and dispose of the plants yourself. All sightings should be reported to Agriculture Victoria by calling 136 186, or by emailing weed.spotters@agriculture.vic.gov.au.

More information about hawkweed can be found on the Agriculture Victoria website.

Did you know that Weed Spotter training is still available to Weed Spotters while face to face sessions are on hold? The online training module mirrors face to face training 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 while the potted plant specimens are locked away in Agriculture Victoria’s glasshouse. It also describes how to report a State prohibited weed and has interactive quizzes and exercises to help you learn.

The course takes about an hour to complete but could be shorter or longer depending on how much time you choose to spend reading the material provided. 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. Recent trainees have said “loved the course!” and “it was a pleasure and very enlightening”. Another who had a group of their staff complete the training said “Thank you for providing access to the Weed Spotter training – I thought the course was terrific. It was clear, informative, and easy to follow”.

To access the training please go to https://learning.agriculture.vic.gov.au/ and create a log in for the site by clicking ‘sign up’. When creating a new account, make sure you select ‘I am a Weed Spotter’ in the ‘Why are you here?’ drop down menu. Once you have created an account, you can select Weed Spotter training.

Image below: The online Weed Spotter training module

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