Weed Management Principles

Weed control

Chemical brands

Chemical brands mentioned on this site are for no other reason than that they are well known local brands. Other brands are available with the same chemical ingredient at rural supply stores. To find all registered chemicals for a particular noxious weed visit the Australian Pesticide and Veterinary Medicines Authority website. A link to their web page is here. Search by state and type the disease/pest in question, (common name is ok) to find the registered chemicals.

Off Label *

In Victoria off label use (not exceeding the maximum rate on the label) is permitted except for restricted chemicals requiring an ACUP e.g Grazon. Off label permits can be applied for at the Department of Environment and Primary Industries (DEPI) or Australian Pesticide and Veterinary Medicines Authority. Off label use can be quite complex and it is recommended that enquiries be made in the first instance with the DEPI. The DEPI website does have good info on chemical use rules. A link to their web page is here

Weed Management Principles

Weeds may be managed using a variety of methods. The most effective management is usually achieved through a combination of techniques. Combining techniques to manage invasive species is also known as integrated management.

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. Repeated treatments will be required.

Things to consider before you begin

It is important not to disturb native vegetation, culturally significant areas or waterways when undertaking weed control works. If looking to undertake weed control works in these areas, consult with the responsible authority to seek advice on the best approach for your circumstances. Contact the Department of Sustainability and Environment, Department of Planning and Community Development and/ or your relevant Catchment Management Authority prior to commencing control works.

Work with your neighbours and encourage everyone to work together to control weeds at the same time. This will help to reduce re-infestation from neighbouring properties and reduce the amount of follow up control work required.

Contact your local Landcare group who will be able to provide advice and information that will assist your weed management program. They may be able to provide equipment, financial assistance or help coordinate a community program. More information about Landcare can be found here.

A long-term approach, regular monitoring and vigilance is necessary to successfully control weeds and, if the property is heavily infested, many years of follow-up treatment will be required. This is because many weeds will regrow from seed and other plant parts stored in the soil.

Always remember to “treat your weeds before they seed”.

Non-Chemical Control Methods Explained

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.

Mulching/Smothering 

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

Pasture Improvement/Re-vegetation

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 Explained

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.

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

Grazing

Use stock such as goats, sheep and cattle.

Weed Identification and Control