Stem injection

Stem injection is used for removing unwanted trees with a diameter of more than 10 centimetres.

This video was sourced from Coffs Harbour Regional Landcare

Before you start, ensure:

  • you have the right safety equipment
  • the weather conditions are good
  • all pets and children are safely away from the treatment area
  • you have read and heeded all herbicide labels and equipment manuals

The equipment you will need is:

  • hat, safety eyewear, long-sleeved shirt, long pants, covered footwear
  • chemical resistant gloves, face shield, mask, impervious apron
  • a drill or small axe or chisel and hammer or machete
  • herbicide, a calibrated syringe or spot gun and a measuring container

Herbicide mixing

Estimate the amount of mixture you will need - be conservative. It is easier to mix up more herbicide than it is to dispose of excess mixture.

Measure out the required amount of herbicide and add it to the container. The mixture rate will be on the label and is usually in the range of 1:1 - 1:4.

Seal all containers and agitate the mixture with a paint brush.

Cut the bark

The stem injection can be made at a convenient height. Using a drill or small axe or chisel and hammer or machete, cut downward at an angle of 45 degrees through the bark to the sap wood.

Apply herbicide

Immediately roll the back of the blade downward opening up a pocket in which to apply the herbicide mixture. Pockets must penetrate the trunk to a depth which reaches the sapwood and they must be angled downwards to enable the herbicide to pool. Take care not to overfill the holes.

Ensure the treated area is not disturbed for 24 hours to allow herbicide uptake.

Treat all around the trunk

Treat each stem of the plant with cuts every 7.5 centimetres around the trunk's entire circumference. The idea is to create two rows of pockets around the tree (one slightly higher, the next row lower and offset from the first).

Clean up

Step one
Any left over mixture must be disposed of in a pit that has been prepared with lime or wood ash. the pit must be situated at least 50 metres away from watercourses.

Dig a hole. The size of the hole depends on the amount of herbicide left over and the equipment risings but must be a minimum of 15 centimetres deep.

Place some lime into the hole and mix with the soil. Then cover the bottom of hole with one centimetre of lime.

Step two
All equipment and empty containers should be triple rinsed to remove all traces of herbicide. Pour any left over herbicide and all rinsing from equipment into the hole.

Cover the hole with at least 15 centimetres of soil.

Finally, cover the area to prevent children and pets gaining access. All herbicides and other hazardous materials should be stored in their original containers out of the reach of children and pets.

More information

For more information send an email to the Invasive species team.