Committee Upskilling
VICTORIAN GORSE TASKFORCE GORSE WORKSHOP
Greg Donaldson and Steve Macklin (Trentham Landcare) attended the Gorse Workshop organized by the Pipers Creek Landcare Group and hosted by Christina Boon(1) of the Victorian Gorse Taskforce (VGT). The workshop, held on a farm on the north edge of Kyneton on Sunday 24th March 2024, comprised a series of field demonstrations and talks describing methods of gorse control and eradication.
Gorse was introduced in Australia in the early 19th century primarily as boundary marker hedging. It’s spread was accelerated during the goldrush period in the late 19th century. When established, gorse forms a monoculture stifling native plants and grasses, as well as providing habitat for exotic animals such as feral foxes and cats. It is also highly flammable, even when green due to high natural oil content. In the central districts of Victoria (covering our area) gorse is classified as a “regionally controlled weed”, requiring private landowners to prevent the growth and spread of the plant on their land. Control or eradication is made difficult because the seeds remain viable for up to 30 years and any damage, disturbance or heat encourages spread and germination of the seeds.
As described on the day, the control of gorse tends to take three main routes:
- 1) mechanical mulching and slashing;
- 2) chemical controls using herbicides; and,
- 3) biological (i.e. goats or competitive planting).
The first two were the main topics of discussion in the workshop.
Mechanical controls.
The first demonstration was a tracked mulching machine called the ‘green climber’. This machine is remotely operated, and uses a horizontally rotating drum with mulching bits (similar to a flail mower but with fixed teeth) to mulch an area of gorse to the ground in short order. The machine was manufactured in Italy, and costs of the order of $200k to buy, so out of reach of most Landcare Groups! Operated by Shane Carey of Macedon Ranges Green Climber2, it is nonetheless available for hire (unit and operator) at about $2.5k/day.
Of course, traditional slashing has its place in the initial control of gorse. However the second demonstration of the ‘ecoblade’ took this a bit further by combining both horizontal blade slashing with simultaneous application of herbicide on the remaining stumps. The slasher unit was mounted on the front of a TEREX skid steer tracked unit, enabling a frontal assault on the gorse clump. Operated by Paul Damaschino of Mountain View Contracting (3), this unit is also available for hire (unit and operator).
One of the advantages of the ecoblade is that it treats the plants (i.e. the stumps) in a more targeted way and thereby reduces herbicide consumption (i.e. it uses 20 litres/day compared to general spraying using 300 litres/day).
Chemical controls
For general treatment of clumps of gorse, direct spraying using herbicide can be used. However, the spraying needs to be very thorough to ensure that all of the plant is treated. This then potentially exposes the operator to the chemical so PPE comprising glasses/goggles, mask (A1/P2 type suitable for mist and vapors), overalls and rubberized gloves/boots were strongly recommended. It was recommended that overalls shouldn’t be washed along with your regular clothes wash for obvious reasons! Fours principal types of herbicide were described for use on gorse:
‘Brushoff’/‘Surefire' (Metsolfuron) – toxic to humans; this lasts for months in the soil, so may affect subsequent nearby planting and can damage adjacent non-weed plants.
“Garlon’ – toxic to humans; less risk of damage to adjacent non-weed plants.
‘Grayzon’ – toxic to humans; remains in the soil for up to 2 years, and should not ne used near water bodies/courses
‘Roundup' (Glyphosate) – relatively low risk of toxicity, less effective than the preceding herbicides.
Other herbicides with similar constituents mentioned include “vigilant” and “woody apparent”.
In addition to the herbicide, dyes may be used to indicate where treatment was applied – although there seemed to be a consensus that dyes were expensive and not particularly effective in practice. However the addition of a ‘surfactant’ would be worthwhile to help the chemical to stick to the waxy, needle-like leaves. Example brand names include ‘Brushwet’, ‘Oasis’ and ‘Spreadwet’.
When dealing with discrete bushes rather than clumps, the use of a ‘dabber bottle’ was recommended. This involved cropping the plant to a few inches above ground level using loppers etc... the exposed cambium is then dabbed with concentrated herbicide (e.g. ‘Vigilant’ or ‘Roundup’) to ensure that the stump is thoroughly treated. A key recommendation was that the application of herbicide must be done within 20 seconds of exposure of the cambium – otherwise the plant will seal up and the treatment ineffective.
Recommended Approach
The generally agreed approach was that a combination of slashing/mulching and herbicide treatment was most effective. However, there were a number of key recommendations:
Direct spraying was much less effective that slashing/mulching first then spraying.
However spraying should be delayed after mulching until the second years re-growth (i.e. the
re-growth should be about knee-high).
Spraying is best done early summer – before flowering and seed dispersion.
After spraying DON’T re-slash for 3 years so as to allow the herbicide to fully penetrate the gorse.
Once the gorse has been controlled, planting with natives like grasses can help prevent re-growth by ‘out-competing’ the gorse.
Any localized bushes that appear can be effectively controlled using the “dabber” method.
All-in-all, the workshop was very informative and interesting field workshop. Thanks to the Pipers Creek Landcare Group and the VGT.
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1 - Communications and Community Engagement Officer – VGT: www.vicgorsetaskforce.com.au
2 - onsitedieselservices@gmail.com; 0429 813 658
3 - info@mycontracting.com.au; 0418 105 658