NOXIOUS weeds can be a prickly problem anywhere in South Gippsland, and the perennial blackberry pest Rubus fruticosus is one of the toughest to eradicate.

Dr Robin Adair from the Victorian Blackberry Taskforce told a recent workshop organised by the Bass Coast Landcare Network that blackberry is now a weed of national significance, ranking alongside rabbits and ragwort as our biggest pests.

“The crown of the blackberry is the plant’s storage part,” said Dr Adair.

“You need to effectively target the crown to effectively control blackberry.”

Weeds are a symptom of the way we manage our land, explained Dr Adair.

“We’re not going to get effective control until we solve our land management issues.”

The workshop at the Poowong Football Club heard that commercially available organic herbicides, such as pelargonium oil and acetic acid-based products, are effective in controlling soft tissue but not the crown of the blackberry.

“The crown is connected to a long root system,” Dr Adair said.

Inorganic herbicides penetrate the plant and get into the roots while allowing grass cover to remain intact helping to prevent blackberries from re-shooting.

“Coverage and time of application when the plant is active is important,” said Dr Adair.

A wetting agent and coloured dye can also make a difference.

“Do not spray on windy days, avoid water runoff and read the label.”

For smaller infestations such as home gardens, Dr Adair suggested using a sponge applicator or weeding wand, with secateurs to cut back the blackberries.

Bigger infestations could require heavy machinery such as a slasher or forest mulcher.

“Only do small areas at a time to prevent the cuts from sealing,” said Dr Adair.

Blackberries can be sprayed immediately before slashing to ensure there is enough leaf area to absorb the herbicide.

Wood-fired weed burners are effective, particularly against annual weeds.

“Weed burners do not leave any residue and are good for controlling seedlings, when it is the right time of year, and safe to use them,” warned Dr Adair.

“Three seconds is enough, the smoke encourages regeneration of native plants.”

Blackberries struggle under a canopy, the last thing you want is bare ground.

“Mulching is an effective tool because mulch insulates the soil and stops sunlight reaching the seeds. To prevent damage to pasture grasses avoid using pre-emergent herbicides.”

Biological control measures used to control blackberry include blackberry rust which occurs naturally and works well during cool wet summers, and cane boring wasp, which is currently undergoing scientific evaluation.

The event was supported by the Partnerships Against Pests program with Luke Vinton and Katie Robinson from Agriculture Victoria speaking about weed control enforcement and biosecurity in rural communities. 

For more information on blackberry control go to vicblackberrytaskforce.com.au.