With concerns increasing about the effects of commonly used herbicides in our landscape, and with many landholders asking what alternatives they can use to control weeds, the South East Wetland Carers Network organized a workshop on Low/No Chemical Weed Control at the end of winter this year.
Here is a summary of some of the options for minimising or avoiding chemical use:
Hand removal of weeds – this is most effective with small, hand-pullable plants or those that can be chipped out with a mattock. As this technique is labour intensive it is well suited to landcare groups with a number of volunteers.
Smart design – to minimise maintenance, design with edges that exclude weeds. Separate exotic species from native plantings using a path adjacent to plantings or a physical barrier buried in the soil to stop grasses spreading into planting areas.
Reduce bare soil and open spaces – this can be achieved through good species selection, planting density, weed mats and mulch.
Mobilise animals to assist you – in the right location these can include goats, sheep, chickens and guinea pigs.
Mowing – to shred weed material, reduce weed biomass and reduce the chance of seed set. Repeated mowing can reduce the vigour of some weeds.
Solarisation – with clear or black plastic to trap heat energy from the sun, raising the soil temperature to a point where weeds and their seeds are unable to survive. This is best implemented in summer and with moist soil.
Mechanical removal – (using excavator/bobcat) for large areas and weeds that are hard to remove by hand. The resulting soil disturbance will usually require follow up weed control, mulching and planting.
Flame weeding – with a hand held propane torch that is used to rupture the cell walls of plants. A slow pass over the weeds will cause the leaves to glow bright green as they are killed, without the need to burn the weeds. Weed seeds can also be killed with this method. See the following video link for a demonstration.
Examples of weeds that can be controlled with flame weeding are Cobbler’s peg (Bidens pilosa), Mother of Millions (Bryophyllum sp.) and Trad (Tradescantia fluminensis). Flame weeding is most effective with smaller annual weeds. Larger perennial weeds may require repeated treatment.
A number of councils have adopted flame weeding and steam weeding as a technique to avoid herbicide use, especially in public areas such as playgrounds and around hospitals. Check with your local RFS for permit requirements before undertaking flame weeding, and take necessary precautions to reduce fire risk.
If you have had success with any of these techniques or with others not mentioned here, send me a message and I can share your results with the network.