How are weeds controlled?
How can I prevent the spread of weeds?
Weed Removal - non-herbicide methods
Digging out plants: Plants with bulbs, tubers and corms must be completely removed from the soil by digging out. Often these plants will reproduce from broken off pieces.
Crowning: This technique is useful for weeds such as asparagus fern, which have their growing points below the surface of the soil. (corms, rhizomes or tufted fibrous root systems).
Hand pulling: This requires holding the plant stem as close as possible to the base of the plant. Gently tug the plant. This will loosen the soil and allow the plant to come free. The plant may be hung up off the ground or piled in a heap.
Winding up: This process is suitable for plants with surface or climbing runners such as Morning glory.
Weed Removal - herbicide methods
Foliar spraying is a complementary or alternative method to some hand removal techniques. It is used in large areas of weed infestations that have a small native component or small dense areas of weeds with no natives. There are three different spraying techniques.
Selective blanket spraying is used in areas with few or no native seedlings,
where weeds have either formed a dense bed or have a large leaf size. Herbicides
and concentration varies depending on the weed species, it is a good idea to
use a Tracer dye so you can see where you have sprayed. Make sure you thoroughly
check the area for natives prior to spraying. Any weeds close to natives should
be removed by hand before starting to spray. Alternatively, young natives can
be covered with cardboard prior to spraying. Spray units with adjustable nozzles
should be set to produce a fine spray, at low to medium pressure
Spot spraying: is useful in areas with native seedlings present. In circumstances where solitary natives are scattered throughout a weed infestation, the individual trees may be covered or marked with a piece of bright coloured flagging tape. An area of about 10- 50 cm around the base of each native or clump of natives should be hand weeded. Spray units with adjustable nozzles should be set to produce a fine spray, at low to medium pressure. The weed clumps are sprayed with appropriate herbicide at the recommended strength plus a tracer dye. If a native is inadvertently sprayed, remove the affected leaves or immediately rinse off the herbicide with water.
Overspraying is described in detail under Madeira vine control.
This is suitable for coppicing and suckering weeds such as Camphor and Privet,
or any weeds which are too large for hand-pulling or have long taproots such
as Ochna. This method provides for no soil disturbance and weed eradication
1. Cut the stem/s 1-2 cm above (a cut stump or stem protruding above the ground can be dangerous to work around and the seeds ability to re-shoot is reduced), ground level using either secateurs, loppers, a pruning saw or a chainsaw, depending on the thickness and toughness of the stem.
2. Immediately apply glyphosate (generally 1:1 or 1:1.5 or 100%) to the cut surface of the stem or, with medium and large trees, to the outside edges of the cut surface. (Herbicides need to be applied immediately after the cut is made because the ability of the plant to transport fluids ceases as soon as the tissues are severed.))
3. Search through the leaf litter to locate any exposed stem or root surface. Scrape the exposed stem or root surface slightly with a knife until you can see a light green coloured layer. (Do not scrape too deeply.) Apply the herbicide to the scraped sections, either with a brush, injector or spray bottle.
4. Follow up as required.
This is a variation of the cut, scrape and paint technique described above,
the difference being the plant is not cut but left intact and scraped. This
technique is suitable for Madeira
Vine, Kudzu, saplings of Camphor
Laurel and Privet as it ensures
the translocation of the herbicide throughout the entire plant.
1. Scrape several sections of the stem along one side only, in lengths of at least 30 cm. The stem needs to be scraped firmly, exposing the fibres and/or light green coloured layer. Be careful not to sever the stem completely.
2. Each scraped section is immediately painted, prior to scraping the next
section, with the recommended diluted glyphosate for the particular weed.
Note: This procedure is described fully in the Madeira Vine section.
A rechargeable drill with a 5mm drill bit, is used to drill holes in the tree. The battery life of the drill will not last very long, so make sure you have charged them up properly. 100mm deep holes are drilled into the sapwood at a downward sloping angle, drilling 1 to 2 holes at a time, then immediately (within 10 seconds) filling the holes with a glyphosate mix dependent on tree type. The holes are drilled approx. 15cm apart in a circular pattern around each and every multi-branch.The holes are easily filled using a drench gun. These are available from the Rural Co-op and Farmcare for approx. $110.00, and are easy to use. The drill method is good in difficult to get to spots (eg. multi-stemmed tree).
Use a small axe to cut into the sapwood at a downward angle. Three rows of cuts are made in a brick pattern around all multi-branches, low to the ground. 1 to 3 cuts are made before immediately filling the cuts with a glyphosate mix dependent on tree type. The cuts need to be filled slowly to avoid chemical spills. The axe is easy to use in readily accessible spots. Note: The cordless drill and the axe could be used together. The axe for the easily accessible trunks and the drill for the hard to get at multi-stems. This way the battery lasts a lot longer.
The tree spear is easy to use but is very heavy like a crow bar. The spear is filled with undiluted glyphosate. The spear is thrust into the trunk on an angle, then pulled back to open the cut. Then a trigger is released and poison in a measured dose is applied and slowly pumped into the tree whilst the spear is still in the tree. Only one row of spears is required in every multi-branch. You can get into a good rhythm with less bending and may find this easy to use, but it is recommended that you try before you buy. The tree spear is available from the Rural Co-op and Farmcare, costing approx $250. It can also be hired from the Big Scrub Landcare Group for $5 per day (members only, membership $10). It is very good for camphor laurel injecting.
Equipment Used for Weed Control
Tools required include a pruning saw for cutting small trunks and limbs:
a small axe or tomahawk for tree frilling:
loppers for cutting small trees and large vines:
secateurs for cutting smaller plants:
a strong sharp knife: and
a chainsaw for cutting large diameter trunks and limbs:
paint brush/poison pot/spray container to apply herbicide.
It is a good idea to mark some part of each tool with bright spray paint to avoid losing them in vegetation.
Usually a knapsack spray unit, such as a 15litre Solo is usually used. It is advisable to only partially fill the knapsack when working on difficult terrain, to reduce the risk of accident. These units should be completely washed and cleaned after use.
When using herbicides, it is essential to equip yourself with appropriate safety clothing.
Key items are rubber gloves, overalls, shoes or boots, eye goggles and a hat. An agricultural respirator is required for moderately and highly toxic herbicides. Avoid any parts of your skin being in contact with any herbicide. Immediately wash any parts of your body which come into contact with any herbicide, particularly your hands before eating.
Glyphosate is a systemic chemical which is inactivated upon contact with the soil. Roundup Bioactive and Weedmanster 360 are products with improved surfactants, making them safer to use near waterways. Do not use Glyphosate within 6 hours of rainfall and where there is likelihood of rain within 24 hours.
LI 700® is a penetrant , which facilitates the transfer of the herbicide
through the surface tissue and is often used for plants with waxy leaves, such
as Madeira Vine and Wandering
Jew. (Oils are also used for this purpose.)
Manufacturers instructions should be followed when using any penetrant.
This will help the chemical stick to the leaves, is rain-fast within minutes and helps spread the chemical evenly over the plant.
Tracer Dyes are used with herbicides to improve efficiency and safety. The
tracer allows areas/plants that have been treated to be identified. The tracer
alerts anyone entering the treated area that a herbicide has been used for a
short period of time. It also helps to ensure that the target plants are treated
and non-target plants avoided.
Commonly used tracer is a red fluorescent dye such as Spraymate Marker Dye®. Manufacturers instructions should be followed.
Metsulfuron is a non-residual herbicide, which is the active ingredient in Brushkiller® and Brushoff®.
An example of the results of tree drilling on Camphor
Laurel using Glyphosate
The photos above show the results of drilling and injecting mature coppiced (multi-trunk) camphors. From left you see a recently injected tree, next to two trees injected six months earlier the perfect perch for seed dropping birds. The photo on the right is a detail showing the red bopple nut (green serrated leaves) thriving in the centre of the recently injected camphor (red leaves).