Declared plants are regulated under the Natural Resources Management Act 2004 due to their weed threat to South Australia’s primary industries, natural environments or public safety. The Minister for Sustainability, Environment and Conservation may declare a weed when some of the powers of the Act are needed to implement one or more of the eight Natural Resources Management boards’ regional strategic plans to manage the weed. Declaration is a tool to limit the establishment and spread of a plant, thereby reducing future costs from its weed impacts and control costs.

Plant species are declared under various sections of the Act relating to:

• Movement – Some declared plants must not be moved on a public road (e.g. as a cutting, seed or potted specimen).
  Inadvertent movement of the plant on animals, soil, vehicles, machinery or produce may also be prohibited.
• Sale – In general, declared plants must not be sold at any outlet including nurseries, pet shops and market stalls.
  Sale of any animal, soil, vehicle, machinery or produce contaminated with these plants is also illegal.
• Noti cation – The presence and location of infestations of the declared plant must be reported to the regional NRM Authority by the owner of the land.
• Control – Land owners are required to take action to destroy or control certain declared plant species present
  on their property. NRM Authorities are also responsible for controlling these declared plants on road reserves, and may have the power to recover costs of control from the adjoining landowners.

Find out what provisions of the NRM Act apply to each declared plant in your area by contacting your regional
NRM o ce. Information is also online at http://pir.sa.gov.au/biosecurity/weeds_and_pest_animals/weeds_in_sa/plant_policies

Some declared garden plants have safe varieties that are exempt from the declaration. These are listed in the policies available at this web link.

Five tips for successful weed control

1 Prevention is cheap – Insist that vehicles, machinery, livestock and produce coming onto your property do not carry weed seeds. Report sales of declared plants. Be on the lookout for Alert Weeds, which have yet to become established in South Australia.

2 Find weeds early – Get to know plants on your property and quickly identify and deal with new threats.

3 Watch your spread – Take measures to contain weed infestations and prevent further seed dispersal across your property.

4 Plan your controls – Obtain information about managing your target weed. Map the area you need to treat. Treat weeds when they are young. Use the recommended control method. Use selective herbicides where possible. Minimise damage to non-weeds. Establish and promote competing vegetation. Refer to the current Weed Control Handbook for Declared Plants in SA, published annually by PIRSA.

5 Persistence, persistence – Continue follow-up treatments for as many years as necessary. Some plants may have been missed, some may have survived treatment and new seedlings may emerge.

Don’t let Caltrop hitch a free ride around our region

In addition to a Netflix binge this weekend, your time could be well spent tackling prickly pest weeds like Caltrop (Tribulus terrestris).

South Australia’s current COVID-19 restrictions coincide with the germination of this declared weed, which spreads like a virus with its spiky burrs transported via shoes, tyres and stock.

Landscape Officer Ben Page from the Northern and Yorke Landscape Board said now is the best time to stop the spread of this opportunistic weed.

“Caltrop is very good at hitching a free ride,” said Mr Page. “Our sheep, shoes and vehicles unknowingly pick up the thorny hitchhikers and drop them off at new sites ready for germination the following year. “With each Caltrop plant producing about 1000 seeds, pulling out the newly-germinated plants before they get a chance to set seed is the best line of defence. “And right now the plants are only small, so they’re easy to pull out by hand or can be controlled with a low rate herbicide.”

Ensuring machinery is clean and minimising stock movement from Caltrop-infested paddocks are also important control measures. For areas already overrun with Caltrop prickles, Mr Page recommends using carpet or rubber-soled shoes to pick them up.
“You can walk around your property collecting burrs in your thongs or better yet, roll out the red carpet for Caltrop! Spread some old carpet on an infested area, walk all over it and then put it in the bin,” he said.

It is also a prime time for other burr weeds to take hold, such as Innocent weed and Khaki weed.
Innocent Weed is a pest of pastures and irrigated horticulture crops, with its burrs injuring stock mouths and guts and contaminating fodder hay, wool and dried fruit.

Similar to Caltrop, Khaki weed is another prostrate, summer-growing weed that has germinated recently as a result of the high rainfall across the region. Known as an alert weed, Khaki weed is a declared plant that poses a serious threat but is not yet established. Its weed seeds only remain viable in the seed bank for two years, so if you control the plant and conduct follow-up management for two years, you can eradicate it from your property.

Landscape Officers from the Northern and Yorke Landscape Board can help landholders by providing a free weed identification service and advice about the best control methods.

https://landscape.sa.gov.au/hf/plants-and-animals/pest-plants-and-animals/pest-plants