Native soil fungi fights giant Parramatta grass

Organic tool to fight foreign weed


Top Stories
Aa

Controlling nature with nature is a concept that drives one Hastings Valley couple to innovate in the paddock.

Aa
Jeremy Bradley in a paddock full of Giant Parramatta Grass where fungi is doing work as a weed killer. Mr Bradley has twice received Australian Government Landcare awards for innovations in sustainable agriculture.

Jeremy Bradley in a paddock full of Giant Parramatta Grass where fungi is doing work as a weed killer. Mr Bradley has twice received Australian Government Landcare awards for innovations in sustainable agriculture.

Thanks to the determination of a couple from the Hastings Valley, there’s an organic alternative that targets introduced Parramatta grass with a native fungi – Nigrospora oryzae – which remains in the soil forever after.

When it’s not diminishing the roots of this weedy grass it is working quite well with the other squillion fungi types already in the soil to break down mulch into usable nutrients.

Hastings Valley innovators Jeremy Bradley and Cathy Eggert took research by David Officer of the NSW Department of Primary Industries and commercialised it using farmers’ nouse and a great deal of passion to produce bags of concentrated Nigrospora which, when mixed with water and sprayed on paddocks, colonises the crown of that grass species only and turns its stalks a sickly orange.

It takes time and at first the results can be subtle – nothing like a squirt of chemical which kills everything. Fungi must first breed up and dry periods, like the one currently being experienced along the coast, makes it more difficult to ‘get going’. But Mr Bradley has photographic proof that the fungi remains established, continuing to nip at the heels of this difficult weed until wet conditions allow it to dispense with it entirely.

Rain, tyres and animal hooves all help with dispersal. An estimation of spread from just one infected plant is about half a hectare in four years and the fungi will keep growing. The fungi may play a role in controlling Giant’s Rat Tail too and trials are underway on the Atherton Tablelands, and in the Burdekin and Fitzroy basins.

The couple say they grew their passion for fungi by initially experimenting with carbon sequestration and sustainable soil management. Mr Bradley has twice received Australian Government Landcare awards for innovations in sustainable agriculture.

“We learnt the importance of fungi in soil – that they turn detritus into stable carbon. In fact fungi are the main pathway to sequestering soil carbon,” Mr Bradley said.

Years later and after a personal investment of $150,000, they were able to make Nigrospora available to consumers for farm scale regeneration of their paddocks. Today they operate out of a clinically clean chamber on their farm at Beechwood via Wauchope, breeding Nigrospora on sterile organic biomass, sending the living organisms to customers in easy to use bags under the Parra Trooper label.

“Now we consider Parra Trooper as just another farm product,” Mr Bradley says. “But we have been on a steep learning curve getting here.”

Key to their marketing campaign has been the promotion of fungi as good citizens of soil.

Managing a difficult immigrant

This is the time of year when graziers in the sub tropics try to limit the spread of Giant Parramatta grass, whose tough leaves will not be tolerated by cattle.

The tropical Asian native, Sporobolus fertilis, is actually capable of producing 85,000 seeds per square metre and if left unchecked can quickly establish dominance in the paddock. 

Landowners –  by law – must do something about it. In the Bega Valley, at the limit of its southern distribution, it must be destroyed. On the mid North Coast the Noxious Weeds Order tolerates suppression.

Chemicals are the tried and true tool in the fight against this weed but come with substantial withholding periods after using Flupropanate (14 days for grazing, 120 days for feed crops) but less so with 2,2-DPA 740 (two days) and nil for glyphosate. 

These chemical groups come with a warning for moderate resistance risk which means their effectiveness will not last forever. And the US refuses to recognise Flupropanate. 

Of course there’s grazing management techniques that can discourage the formation of bare soil patches – which Sporobolus love to colonise. Keeping paddocks  appropriately stocked and managing grass growth using cell grazing is key in that equation.

More information: http://weeds.dpi.nsw.gov.au/Weeds/Details/58

Aa

From the front page

Sponsored by