Invasive weed Tropical soda apple impacts Northern Rivers farmers

By Sarah Waters

Farmers and landowners in the Northern Rivers are being urged to keep an eye out for any unfamiliar weeds that may appear on their properties and have them identified immediately.

Last year’s flooding caused a number of invasive weed species to spread throughout the NSW north coast, including the invasive Tropical soda apple (Solanum viarum) and Parthenium weed.

Tropical soda apple has a NSW biosecurity control order and is recognised as a serious threat.

It is an aggressive and prickly shrub with yellow fruit, which grows up to two meters, and thrives in subtropical environments.

It invades open to semi- shaded areas, particularly pastures and riparian zones, displacing native plants and taking over grazing land.

There are 300 sites with tropical soda apple in the north coast region which are all under active management to help control it.

Rous County Council’s Weed Biosecurity and Bush Regeneration

Manager Rhett Patrick said tropical soda apple was having a huge impact on farmers.

“That seems to be the one weed we are dealing with the most and is having the biggest impact,” Mr Patrick said.

“Any viable grazing land on the north coast it’ll totally dominate those spaces and could grow to 100 per cent density (if uncontrolled).

“The nature of the weed it just readily invades any desirable pastures, cropping areas and riparian zones,” he said.

The noxious weed is spread by stock eating the shrub’s fruit, floating downstream or being stuck to vehicles.

Each fruit contains 200 - 400 seeds, which can germinate in six to 12 weeks.

Mr Patrick said landowners need to be vigilant and recognise what species of weeds they have on their property.

“If there’s anything strange or unfamiliar that pops up on your property find out what it is.

“Talk to your local weed officer or agronomist - the best way to get rid of those (invasive) species is to get onto them before they can spread any further.”

Another weed species, which has spread significantly since the flood is Frogbit, a floating water weed with round, glossy leaves, that forms across freshwater surfaces.

Before the flood, Frogbit was identified at Boomerang Creek near Dorroughby, but post-flood it has been found all the way down to Woodburn.

A site in Ewingsdale contained a small patch of Frogbit prior to the flood, but it has since spread 10kms to Simpson’s Creek.

The current drought also poses a risk for more invasive weeds to enter the region as farmers bring in feed for their stock.

Mr Patrick said it was a stressful time for farmers, but he asked them to be mindful of where their fodder is coming from and what weed risks are in that area.

Fodder needs to be placed at a designated site where it can be regularly monitored for any new weeds or plants that may pop up around it.

Farmers and landowners are also asked to check any roads or tracks which the fodder has been transported along to make sure nothing is growing from those areas.

If cattle are bought from a property with tropical soda apple, that they have consumed, farmers are advised to keep them in a holding paddock for seven days until they pass the seed.

Rous County Council has a number of weed identification resources, including handbooks and a ‘Report a Weed’ form on their website.

Community members are welcome to speak directly to Rous weed biosecurity officers, who can answer any questions.

The NSW Department of Primary Industries (DPI) also has the WeedWise app which landowners can download to help them identify weeds.

If farmers or landowners identify a small patch of weeds on their property, they can be pulled out, otherwise if they are spread over a large area, an appropriate herbicide may have to be used.

For more information please visit: rous.nsw. gov.au or www.dpi.nsw. gov.au