February 2022 Regional Weed Wrap

The change in seasonal conditions following the recent prolonged drought has led to an explosion for many weed species. St John’s Wort, Blue Heliotrope and Parthenium Weed are the focus of this edition.

St John’s wort Explosion

The change in seasonal conditions following the recent prolonged drought has led to an explosion of St John’s wort (Hypericum perforatum) in many local government areas across the North West and neighbouring Local Land Services regions.

North West Regional Weed Coordinator, Pete Dawson said many conscientious landowners who in the past have had effective control programs have been astounded by what has turned up this year and are wondering where it has all come from.

“Given that each plant can produce up to 33,000 seeds per year and many of those seeds can remain viable for over 10 years, livestock numbers have been dramatically reduced and pastures are still in a recovery phase,” Mr Dawson said.

‘That, topped off by some of the best rainfall in over 15 years, it is not surprising to see this explosion of weeds, particularly St John’s wort.

“The North West Regional Weed Committee encourages all landholders to monitor their properties for the presence of St John’s wort.

“Implementing control programs as soon as possible will ensure compliance with your General Biosecurity Duty under the NSW Biosecurity Act 2015 and help reduce the impact on their property, farming business and neighbours.”

St John’s wort is native to Europe, Asia and North Africa. It was brought to Australia in 1875 as a garden plant and was traditionally used in herbal medicine.

St John’s wort is commonly spread by livestock and native animals, vehicles and machinery by seed and rhizome fragments.

The sticky seed capsules stick to animals. Seeds are also carried in the digestive tracts of animals. Wind may spread seed over short distances however water, machinery, humans, livestock or feral and native animals spread seed over long distances. Roots sucker and new plants grow from rhizome fragments. Cultivation can move / spread root fragments.

St John’s Wort will outcompete pastures, is poisonous to livestock and can impact property values.

The most successful control programs include implementing integrated weed management tactics on a seasonal basis over many years including a mix of selective chemical control and grazing management strategies to ensure strong pasture competition and the reduction in seed numbers.

Landholders should check their Regional Strategic Weed Management Plans for control priorities and recommended measures. Regional Strategic Weed Management Plans - Website - Local Land Services (nsw.gov.au)

In the North West Local Land Services region, St John’s wort is a Containment priority depending on which Local Government area your property is in.

  • Whole of region: The plant should not be bought, sold, grown, carried or released into the environment.
  • Exclusion zone: Land managers should mitigate the risk of new weeds being introduced to their land; land managers should mitigate spread from their land.
  • Core infestation: Land managers reduce impacts from the plant on priority assets.

Contact your Local Council Weed Biosecurity Officer for advice on how to best manage St John’s wort on your property and check out the NSW DPI Weedwise website.

Blue heliotrope

Are you struggling to control Blue heliotrope (Heliotropium amplexicaule) on your property?

NSW DPI, in partnership with Local Land Services are currently working on the development of a Blue heliotrope best practice management manual. As part of this project a series of state wide workshops will be rolled out over March and April with land managers, agronomists and weeds professionals invited to participate to better understand blue heliotrope and how to manage it.

The workshop will present current information and seek land manager experiences on identification and distribution, life cycle (growth and reproduction), influencing factors (soil, climate, location preferences), how and when it spreads and management options. The results from an ongoing herbicide trial will also be shared with the participants.

Information gathered will help in the development of a best practice management manual for blue heliotrope that will be available to land managers in late 2022.

Presenters and support on the day will include local land managers, technical experts and staff from Local Land Services and DPI. Workshops facilitated by Wild Matters consultants.

Land managers and industry professionals can register their interest in this workshop by contacting the North West Local Land Services Regional Weed Coordinator, Peter Dawson via email peter.dawson@lls.nsw.gov.au

Parthenium weed

Local control authorities are continuing to undertake high level surveillance in areas surrounding known incursions of Parthenium weed (Parthenium hysterophorus) including high-risk sites and pathways, particularly along roadways, stock feed out areas and riparian zones.

Infestations range from single isolated plants on roadsides, medium infestations around feed out areas to heavy infestations covering a couple of hectares.

Fresh germinations are already occurring and being treated and are expected to increase over the coming months.

If you think you have seen this dangerous plant do not attempt to remove or treat it yourself. Contact your local Council Weed Biosecurity Officer or call 1800 680 244 for free assistance.

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