Weeds of Blue Mountains Bushland

Controlling Weeds

Using Herbicides

Many of the weed control techniques suggested in this section involve the use of herbicides.

Herbicides are poisons, and should be handled with the greatest respect. They can be absorbed very easily through the skin, by breathing the vapours, and by ingestion (eating or drinking).

By law, herbicides must be used strictly in accordance with the manufacturer's label. They should be kept well out of the reach of children, preferably secured in a locked cabinet.

They should always be stored in the original labelled container.

Use of Herbicide: Safety Precautions

Read the label before opening the container and follow the instructions exactly.
Wear protective clothing: long sleeves, long pants, sturdy shoes, gloves, eye protection.
Always wear waterproof gloves.

Herbicides are poisons:
wear protective clothing.
A respirator is advised when mixing or pouring the liquid.
Do not eat, drink or smoke while using herbicide.
Keep children and pets away.
Wash skin and equipment afterwards. Wash contaminated clothing separately.
Clean up any spills, including on your skin, with large amounts of water, or by shovelling up contaminated soil and disposing of it at the tip.

Types of Herbicide

There are two widely used herbicides licensed for use at home:

Glyphosate, which is sold under various trade names, including Roundup® and Zero® (which have different concentrations), and
Triclopyr, which is sold as Tree, Blackberry and Woody Weed Killer (etc).

How Herbicides Work

Glyphosate is a systemic, non-selective herbicide. It inhibits the action of an enzyme, preventing the production of an amino acid essential to plant life and growth. It must be applied to green leaves, or directly to the plant's sapwood, which lies under the bark.
Triclopyr is a selective systemic herbicide for woody and broadleaf plants. It is a growth inhibitor which moves to the plant's roots, stops growth, and eventually leads to the death of the plant. Triclopyr can be applied to green leaves and to bark.

Herbicides - Conditions of Use

Herbicides must be used according to the label, or according to National Registration Authority Permits.
If the plant on which you wish to use the herbicide is not named on the label, contact Council for permit information.

Herbicides, Waterways and Steep Land

Some of chemicals which are added to herbicides are not safe to use near waterways. They have the potential to seriously affect the quality of aquatic ecosystems.

If you need to remove weeds, particularly trees, within 20 metres of any kind of watercourse, even a drain that runs only when it is raining, you must seek advice and assistance from:

Council's Environmental Management Section (phone 4780 5000)

This also applies to the removal of trees from very steep land.
See Erosion Alert.

When to Treat with Herbicide

Apply herbicide when the plant is actively growing.
Do not apply herbicide when the plant is under stress: extreme heat or cold, drought, waterlogging, or disease.
Choose early morning or late afternoon in summer; midday in winter.
Do not apply when wet or windy weather is anticipated.
For many plants, especially bulbous plants and those which sucker, the best time is from summer to autumn.
Treat deciduous plants in late spring or in summer, when in full leaf.

Erosion Alert

Try to stage weed removal. Large areas of exposed soil are an open invitation to weed invasion. They may also cause soils to erode, carrying weed seed into the bush.

Mulch bare soil, and stabilise it by planting bush-friendly plants into it as soon as possible.

The Cut and Paint Technique (Woody Weeds)

Suitable for small to medium sized woody weeds up to 10cm in diameter (or larger shrubs if using a chain saw).

Tools for the job: loppers, bush saw, herbicide applicator, impervious gloves

Clear the ground around the base of the plant.
Cut the stem horizontally as close to the ground as possible, using secateurs, loppers or a bush saw.
Make sure there is no soil on the cut surface.
Make cuts horizontal to prevent the herbicide running off the stump. Sharp angled cuts are also very hazardous.

Apply undiluted herbicide to the cut stem immediately. Squeeze, not squirt, if using an applicator.
Apply herbicide immediately after cutting - within 20-30 seconds - before the plant cells close and the translocation of the herbicide ceases.
Ensure there is no runoff of poison.
Use as little herbicide as possible.

If cutting at the base is impractical, cut higher to get rid of the bulk of the plant, then cut again at the base and apply herbicide.

If plants resprout, cut and paint the shoots after sufficient regrowth has occurred.

Stem scraping (see below) can be very effective on certain woody weeds, for example Japanese Honeysuckle, Blackberry, vines and rhizomatous plants.

The Scrape and Paint Technique (Vines and Scramblers)

This method is suitable for vines and scramblers with woody stems.

First read about using herbicides, safety precautions, the conditions of use, and the cut and paint technique (see above).
Using a knife, and starting from the base, scrape 20 to 100cm of the stem to expose the sapwood, just below the bark.
Within 20-30 seconds, apply undiluted herbicide to the scraped area.
Try to scrape all the main stems.

Tips for controlling vines

Do not ringbark the stem: scrape only one third of the diameter or less.
Stems larger than 1cm in diameter can be scraped on both sides.
Vine curtains can be cut at chest level, then again at about 30cm. Scrape or cut and paint these lower stems, or spray new growth.
Blackberry can be cut back to 1m if there are plenty of leaves. Dispose of the mass of the plant, then scrape or recut and paint the cut stems.
It is best not cut Madeira Vine - just scrape the stems. Theoretically, the herbicide will translocate to both aerial and underground tubers from the stem scraping.
Pulling vines (especially twiners) out of trees and shrubs may do a lot of damage. They are best left hanging to die. Vines such as English Ivy, which cling to bark, should also be left to die on the tree. The loss of bark resulting from pulling them down will cause serious harm.

Stem and Leaf Wiping

This method is suitable for herbaceous plants with bulbs, tubers or corms, eg, Montbretia.

photo: © Lyndal Sullivan

First read about using herbicides, safety precautions, the conditions of use, when to treat with herbicide, and the cut and paint technique.
Remove and bag any seed or fruit.
Using a weed wiper, start at the base and wipe all the stems and/or leaves with a dilute mix of herbicide.
If leaves have soil on them, wipers must be regularly washed out.

Take great care when wiping: do not allow the herbicide to touch your skin or to run off into the soil, or to get on a non-target plant. Wear safety glasses in case of splash.

Coming soon to this site:
How to make your own weed wiper

Stem Injection

Stem injection and Frilling or Chipping are methods for treating shrubs or trees greater than 10cm in diameter at the base, such as Large Leaf Privet and Camphor Laurel.

Method 1 Injection

Use a cordless drill (9mm bit), a hammer and chisel, or brace and bit.
Below any branches, drill or chisel holes round the base of the tree, into the sapwood, angled down at 45°, and at 5cm intervals.
Make the holes about 4cm deep.
Within a few seconds of drilling each hole, fill it with undiluted herbicide.
Do not ringbark the plant.
Use this method only when falling branches (as the tree dies) will not be a safety hazard.

Tree Injection

Method 2 Frilling or Chipping

If a drill is not available, use a sharp chisel or axe and make a deep cut at 45º into the sapwood.
Fill with undiluted herbicide immediately.
Repeat these cuts around the base of the tree at 5cm intervals.
Do not ringbark the plant.
See When to Treat with Herbicide.

Tools for Tree Injection

Stem injection on an old Small-leaf Privet using a brace and bit

Spraying

This site does not set out to give a thorough treatment of the subject of spraying. Consider all other options for weed control first.

First read above about using herbicides, safety precautions, the conditions of use, when to treat with herbicide, and the cut and paint technique. See also Erosion Alert.

Spray at the correct stage of the plant's growth, at the right time of day, and when there is no wind. See When to Treat with Herbicide.
Spray at low volume, using the minimum amount of herbicide.
Spray low: often it is best to cut a weed down to near ground level, then spray the regrowth.
Avoid off-target damage, ie, spray drift on to desirable plants.
Do not spray near watercourses: contact BMCC Bushcare Section (phone: 4780 5623).

Carefully follow all safety directions and instructions for your sprayer and the herbicide.

Wear protective clothing and spray low.

Keep children and pets away from the sprayed area until the next day.

Hand Removal of Weeds: Crowning

Suitable for seedlings, herbaceous weeds, and many grasses.

Before starting work, remove and bag seeds and fruit and place in the bin.
If the weed has a tap root, push a narrow trowel or long knife deep into the ground beside the root. Loosen the soil. Work round the root, then work the plant out gently.
Many plants which will not regrow from their roots (eg many grasses) can be crowned: Hold leaves and stems together, and use a knife to cut through all the roots below the 'crown'.
Ensure there is no erosion of cleared soil by wind or water - eg, by mulching.
See Erosion Alert

Digging Out

On previous pages, you will find advice on using herbicides to control weedy plants: often this causes minimal disturbance and less germination of seedlings. But, if you have the energy and the space in your garden, you can almost always take the dig option, making sure that you remove all the parts of the plant from which it can regrow. Ensure there is no erosion of cleared soil by wind or water - eg, by mulching.
See Erosion Alert

Seedlings and small plants may be pulled by hand when the soil is moist.
Plants with bulbs, corms or tubers (eg Montbretia, Madeira Vine) may need deep digging to ensure complete removal. Bag bulbs, corms and tubers and send to the tip; do not compost.
Removal of well established Agapanthus will require a mattock, or even a crowbar. Try cutting through large clumps with an axe.

Digging out and bagging Montbretia
before seed set, Lindeman Road, Leura.

Illustrations: Norman Yeend and Virginia Bear