Next Steps – control methods

(the following is an edited version of information provided on the Bass Coast Landcare Network website – with permission)

Once you have identified that you have an unwanted plant there are a number of ways, or combination of ways, that you can manage the problem.

In general, the principles of a successful weed management program are:

  • Clean (or weed free) areas should be managed to keep them free of infestation.
  • Lightly infested areas should be treated as a priority to minimise further spread.
  • Heavily infested areas should be tackled progressively as part of a property management plan.

In all cases vigilance is required. Remember always be observant and one weed left alone will make a forest!   “Treat your weeds before they seed”.

Non-Chemical Control Methods

  • Biological Control  

Biological control is the use of one living species, the agent, to control an unwanted species, the target. Agents can be diverse, and weeds are commonly controlled by introducing bacteria, viruses, fungi and insects that inhibit their growth. Biological control can’t eradicate a pest species, but it can reduce the weed population and slow down invasion. It can be a lengthy process and results may vary as weed growth varies according to climate and land use.

  • Cultivation 

Cultivation has two main objectives, to prevent seeding and to destroy existing plants.

  • Fire 

Controlled burning for the management of  large woody weed infestations to enable access for follow up control treatments such as hand removal or (if using chemical) foliar spraying or cut and paint methods. Follow up essential. Many safety concerns. Consult CFA and DSE/CMA (if infested area involves public land).

  • Hand Pulling  

Very effective in small areas or with isolated plants. Some plants will regenerate unless all root material is removed.

  • Mechanical– Use of Machinery   

Suitable for initial removal of large infestations of woody weed to enable access for follow up control treatments such as hand removal or (if using chemical) foliar spraying or cut and paint methods. Ensure machinery is cleaned down before moving to a new area.

  • Grazing 

Use stock such as goats, sheep and cattle. Horses are not the best option as they are very selective grazers.

  • Mulching/Smothering  

Involves placing a thick layer of material on the ground surface which weeds struggle to penetrate.

  • Providing competion

The aim of the game for weed control is to ultimately  replace weeds with plants that we do want.  Once weeds are down to a manageable level, plant competition is an important means of weed control.

In a pasture situation, increasing competition through good grazing management and addressing soil fertility will help to control many weeds. In fact, once competitive pasture is established, the pasture weeds drop out the picture altogether as is the case with certain weeds in a bushland environment. In areas where you want native vegetation, weed control programs should include revegetation using suitable native plants.

  • Slashing or Mowing  

May be used to delay seed production until a more suitable means of control can be undertaken. Care must be taken as weeds, if in seed, can spread easily using this method.

  • Solarisation 

A technique that blocks light and uses the heat from the sun to ‘cook’ weeds. Usually involves covering the infested area with a plastic sheet, sealing it tight and leaving it in place for several weeks. Suitable for plants that grow along the ground i.e. creepers. Adequate sunlight is required for this technique to be truly effective.

Chemical Control Methods

  • Cut and Paint  

Suitable for many woody weeds and some climbing creepers. The plant is cut off close to the ground and herbicide is immediately applied to the cut surface. A staggered pruning technique may be used for larger trees with herbicide applied at the last cut.

  • Drill and Fill 

Chips or frills are made into the trunk of a woody weed close to the base of the trunk with an axe or tomahawk with herbicide immediately applied to the cut surface. Cut to penetrate through the hard outer bark to just into the soft bark layer.  Alternatively, an angled hole can be drilled into the sapwood just below the bark and herbicide immediately apply the herbicide.

Image from “Weeds of the Blue Mountains”
  • Scrape and Paint 

A variation of cut and paint that is more appropriate for treating large woody, vine-like weeds. The outside bark of a vine is removed with a knife and the exposed inner tissue is immediately  applied with herbicide.

  • Foliar Spray 

An appropriate herbicide applied as fine droplets to the surface of foliage using a knapsack or spray unit.

Example of vehicle mounted spray unit