Weed Control Techniques

 

There are a number of effective techniques available to manage weeds. It is important to take into consideration the situation (i.e. location, risk of off target damage etc.) and species characteristics.

Manual (non-chemical) control

Hand pulling

Hand pulling needs to be done carefully to ensure there is minimum soil disturbance as weeds flourish when soil is disturbed.

Removal of small weeds can be achieved by placing one hand flat on the ground with the weed between two fingers. As the hand is pressed toward the ground the second hand can carefully remove the weed. If soil or leaf litter is disturbed, it should be replaced to minimise the opportunity for another weed to become established.

The same principle is used when removing slightly larger weeds. In this situation disturbance is minimised by placing a foot either side of the stem base. While bending knees use your legs to pull the plant out gradually with both hands.

You may choose tools to assist weed removal in sensitive bush settings. A knife is excellent for teasing weeds out of the ground and in between desirable vegetation. Just remember to replace any disturbed soil or leaf litter.

A tree popper is useful to remove larger woody weeds as these work as a lever, making it easier to remove weeds.

Remember: Pulling weeds by hand should only be done when soil is relatively moist. If the soil is too dry hand removal risks excessive soil disturbance, or the plant may break away from the roots resulting in regrowth later in the season.

Slashing

Slashing can be used on annual and perennial weed grasses and shrubs. When using this method, care needs to be taken to minimise damage to herbaceous native plants. Slashing is usually done using a brushcutter or hedge shears.

Annual grasses should be high slashed (10 cm above ground) before seed heads start to develop, typically in late winter and may require follow-up slashing after 4-6 weeks. As they are annuals, preventing the production of seed will ensure their seedbank will diminish with time.

Perennial grasses can be slashed at any time of year, however best results will be obtained during winter and spring.

Chemical control

Under Victorian legislation, there are controls on the use of agricultural chemicals. It is the responsibility of the user to be familiar with this legislation.

Each chemical has a ‘product label’, which documents the approved use and the approved rate. Other controls include the requirement to possess an Agricultural Chemical User Permit (ACUP) to allow use of certain chemical products.  Choose only products registered for use in your particular situation.

Important: Read the product label carefully and ALWAYS follow all label instructions.

Chemical retailers can provide information on chemical products registered for your situation and supply a ‘material safety data sheet (MSDS)’ which outlines the health and safety information about a product. This information is also available from chemical manufacturers and product labels are available from Australian Pesticides and Veterinary Medicines Authority.

Remember to take great care when decanting (off-site), transporting, using and storing chemicals. Keep good records, and wear appropriate PPE, such as safety goggles and chemical resistant gloves (under your regular gardening/riggers gloves). Keep plenty of water and soap on hand in case of emergencies and always wash hands after using herbicides.

Cut and Paint

The cut and paint technique is often used for large woody weeds or when the soil too dry for hand pulling. Many woody weeds, with the exception of Pines and some (non-indigenous) wattles, will grow back if not treated with herbicide.

First cut the stem close to the ground then apply neat herbicide(or 90% diluted with 10% water) to the exposed stump. The herbicide needs to be applied with 10-20 seconds as many weeds begin sealing wounds within seconds, which reduces the absorption and effectiveness of herbicide.

Using a dabber bottle is a relatively safe way to apply herbicide, as it helps with direct and consistent application, however it is important to check for leaks before commencing work.

 

 

 

 

 

 

 

 

 

Using a dabber bottle is a relatively safe way to apply herbicide, as it helps with direct and consistent application, however it is important to check for leaks before commencing work.

 

 

 

 

 

 

Drill and Fill

The drill and fill technique is very useful for larger woody weeds.
The drill and fill method can be used on any woody weeds that have a base 4 cm in diameter or larger. A drill is used to drill 45 degree holes into the plant’s cambium layer (the thin, actively growing tissue between the bark and the wood of a tree). The hole is then immediately filled with herbicide.

 

The plant will drop its leaves within 6 weeks and die within a few months. It will be necessary to monitor the plant and if it resprouts, the process will need to be repeated.

The soil beneath large woody weeds usually contains huge numbers of seeds from the parent plant. These seeds will germinate and, if left untreated, will become a worse problem than the original plant. It is essential that follow-up control of seedlings or regrowth is undertaken in subsequent years.

Important: do not use this technique where there is a risk of the dying tree falling on roads, paths, dwellings or areas frequented by children such as playgrounds.

Frill and Fill

Instead of using a drill, a small hatchet or a chisel with a mallet can
be applied to the trunk at a 45 degree angle to frill, or chip, the
outer layers of the trunk, exposing the cambium layer.
These cuts must circle the entire trunk, at 5 cm intervals, however ensure that the plant is not ringbarked as herbicide will not be transported into the plant. Herbicide should be immediately applied to the exposed cambium.

Wiping

Wiping foliage using a weedbrush or tongs is extremely useful on plants with bulbs, tubers or corms, especially those that are difficult to remove completely through hand removal. For plants with waxy leaves, it may be necessary to add a wetting agent or surfactant (a substance which reduces the surface tension) to allow the herbicide to be absorbed into the plant. The brush or tongs are wiped onto the foliage of individual weeds.

Stem scraping

 

Spraying

Large scale chemical spraying is not suitable in bushland settings due to the risk of off-target damage and potential spray drift. Therefore is not included in these recommended management techniques.

However should your situation require you to “spot” spray, training in the safe use of chemicals should be undertaken prior to using herbicide and appropriate safety equipment should always be used to minimise harm to the operator.

When spraying, the manufacturer’s label rates should be referenced and used accordingly. If possible, add dye marker to the spray equipment to ensure that weeds are not sprayed twice. This will also help avoid off-target damage and improve personal safety.

Spraying must be done in the correct season when the plant is actively growing and should be avoided in windy conditions. This will also use less herbicide. When spraying, care needs to be taken to minimise off-target damage.

Alternatively, engage a specialist bushland restoration contractor to do this work for you.

Use of Glyphosate

Used carefully and appropriately for bush regeneration, glyphosate-based herbicides are very useful and safer than most alternatives.

The main advantages are:

• generally less persistent in soil, although will persist in
  sand for several weeks
• easy to measure and use
• relatively cheap

The most important disadvantage with glyphosate is that it is
non-selective; it will kill any plant with which it comes into contact.

It is essential that correct training in bush regeneration is undertaken before glyphosate is used amongst native vegetation.