WHY CONTROL WOODY AND ENVIRONMENTAL WEEDS?

INTRODUCTION

In 1803, just 15 years after the First Fleet arrived, the then Governor listed 292 introduced plants in Australia. Of these, at least nine subsequently became important noxious weeds, including Gorse, Scotch Broom and Sweet Briar.

The need for weed control was first recognised in Australia by legislation in the New South Wales Municipalities Act, 1867.

Weeds today impose an enormous and increasing social and economic cost (estimated at $3 billion per year), and productivity burden on rural Australia.

BENEFITS OF WOODY WEED CONTROL

Controlling woody weeds will provide the following benefits:

1. INCREASE THE CARRYING CAPACITY OF YOUR PROPERTY – Controlling woody weeds means that there is more productive pasture available and in turn allows you to carry more livestock.
2. INCREASE IN THE VALUE OF YOUR PROPERTY – Properties that are free of woody weeds are of greater value than those that are infested.
3. MAKE MUSTERING EASIER – Large infestations of woody weeds provide stock with a hiding place when being mustered.
4. REDUCE THE RISK OF FIRE – Large infestations of woody weeds are a fire risk, particularly in periods of prolonged dry weather.
5. REDUCE THE INCIDENCE OF VERMIN – Large infestations of woody weeds provide an ideal habitat for the breeding of vermin e.g. rabbits.
6. COMPLY WITH GOVERNMENT LEGISLATION – Controlling declared woody weeds is the legal responsibility of the landholder.
7. MINIMISE STOCK LOSSES – Some woody weeds are poisonous to stock and by controlling woody weeds stock losses will be minimised.
8. PROVIDE STOCK WITH EASIER ACCESS TO WATERWAYS – Because woody weeds flourish around water, stock have reduced access to waterways.
9. ENVIRONMENT PROTECTION – Woody weeds invade and dominate native vegetation if left unchecked.
10. EROSION CONTROL – Replacing woody weeds with a dense competitive pasture stand (and correct grazing management) protects valuable topsoil.

INTEGRATED OPTIONS FOR WEED CONTROL

CHECK

RAIN

SPRAY

GRAZE

MECHANICAL

DE-STOCK/FENCE OUT

BURN

SEED

AERIAL FOLIAR SPRAY

BASAL SPRAY

BOOM SPRAY

WHICH METHOD OF TREATMENT SHOULD I USE?

INTRODUCTION TO TREATMENT OPTIONS

There are a number of different methods you can use to treat woody weeds. The option you choose will be determined by the size of the problem, the resources you have available and time constraints you are working to.

Refer to Control Guide Tables and product labels for correct application rates.

STEM INJECTION APPLICATION

Make horizontal cuts with a narrow-bladed axe (5-7cm wide) through the bark of the woody weed into the sapstream at waist height. Space these at 10-13cm centres. Leave the axe in the cut and immediately (within three seconds) apply the herbicide down the axe blade, to ensure the full dose enters the sapstream. This is necessary because the plant can seal the cut quickly, thus barring the chemical penetrating into the sapstream.

Do not treat trees with poor sap flow that occurs when plants are stressed.

Where low branches are encountered place a cut immediately below the branch.

CUT STUMP APPLICATION

Cut stump application is the preferred method for saplings that are too small to be stem injected.

BRUSHCUTTER APPLICATION

This brushcutter takes the back-breaking effort out of the cut stump application method. It uses a high-powered tungsten-tipped cutting blade to remove the top growth as close to ground level as possible. A sprayer attachment delivers a dose of herbicide almost immediately to the cut surface.

BASAL BARK APPLICATION

Do not treat if the stems are wet or charred as this prevents the herbicide from penetrating through the bark.

Make sure you thoroughly treat the whole circumference of each stem from ground level to a height of 30cm.

Some woody weeds can be treated when basal diameter is greater than 5cm. Refer to the product labels for details.

TORDON DSH

Injection at or near ground level is recommended in areas…..

FOLIAR SPRAY APPLICATION

This method normally refers to high volume application using a handgun to treat the foliage of the plant. It is recommended to use a No. 5-8 tip on your gun and calibrate your pump pressure to 700-1500 kPa.

Ensure you treat the entire leaf area of the plant to the point of run-off, with thorough coverage of the crown, runners and tips. A knapsack can be used to ensure that the full volume is delivered to the target plant.

PELLET OR GRANULAR SOIL APPLICATION

Apply pellets to the soil prior to spring or summer rains.

It is essential that the root area of the woody weed is evenly treated with the pellets or granules. This means covering the ground under the canopy from the root crown or stems to 30cm beyond the dripline (see illustration above).

The herbicide acts by moving into the root zone of the weed following rain, and from there it is absorbed into the plant.

GRASLAN AERIAL APPLICATION

GRASLAN HERBICIDE is applied to areas greater than 100 hectares during winter and spring prior to the spring storms. A fixed wing aircraft is used to apply product in Queensland and a helicopter in the Northern Territory.

Before Graslan can be applied, a Dow AgroSciences representative will conduct a paddock inspection to ensure Dow AgroSciences and government environmental guidelines are followed, as well as recording all details of the job. The area is recorded using GPS equipment. A contract is written and our application co-ordinator will arrange for Graslan to be applied at a time when the plane is next in the area. As this process can take some time to complete, it is essential to plan and organise an inspection early in the year.

AERIAL SPRAYING APPLICATION

Apply herbicide in not less than 200L/ha. Spray with a calibrated aircraft using the full overlap opposite pass technique. Nozzle combination should not be less than D8/45°.

Spraying in wind exceeding 10km/h, temperature above 30°C, or relative humidity below 50% is not recommended.

SPRAY DRIFT

Spray only when there is no movement of air towards non-target susceptible vegetation or waterways. Drift can be greatly reduced by using nozzles and spray pressures which produce a minimum proportion of small, drift-prone droplets e.g. lower pressure, larger droplets and higher spray volume. Under ideal conditions, spraying can be carried out near susceptible non-target plants and waterways by separating them with a suitable size buffer area.

GROUND BOOM SPRAY APPLICATION

For pasture weeds, sprayers should be calibrated to deliver a minimum of 100L/ha of water with a droplet size of 150-350 microns.

Use higher volumes of water in dense pastures to achieve better penetration and coverage. It is recommended that you use flat fan nozzles and spray pressures of 200-300 kPa with boom height set to ensure double overlap of nozzle pattern at the top of the weed canopy.