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Stem injection

The application of herbicide should be made directly into the vascular system (xylem and phloem),using either one of these application procedures:

  1. Cut + Injection

at the height most convenient to the operator, several cuts are made, at a 45º angle, up to the sapwood. The cut doesn’t to be particularly deep but it should cross the bark and cut the most external part of the wood.

The cuts may be done with an axe or a saw.

Several cuts should be made at the same height of the trunk as to almost touch, leaving approx 2-4cm of uncut bark between them.

For smaller plants only 2 or 3 cuts are necessary and they should not be deep, to avoid the plant breaking.

Immediately after each cut the herbicide is injected in the incision with a squirt bottle: apply slowly approx. 1ml (0,5 to 2ml depending on the size of the cut) of herbicide in each incision (normally squirt bottles shoots +/- 1ml); the herbicide should remain inside the cut.

After treatment the tree will rapidly brown and look dead. However, it is important that the tree stays for another year and should not be removed – this way ensures that the tree uses part of the reserve sugars in the roots.

In deciduous species, the best application season is in  summer or spring, or in dry weather and when the plant has its leaves completely expanded.

  1. Drilling + Injection

With a drill, make holes around the trunk.

Immediately, apply the herbicide in each hole. The bigger the tree, the more holes you need.

There are drills that are adapted for this function that include the herbicide injector. However, a normal drill is equally effective as long as you apply the herbicide immediately after drilling the hole.

Depending on the species and the time of year, this method is generally highly efficient in terms of mortality. It inhibits sprouting from the stump and roots, reducing costs in continuity control methods in the medium-term.

If well applied, the herbicide will not seep out and small quantities are used.

It affects the radicular system more severely than other methods that use herbicide.

Time-consuming and quite costly in the short-term, if performed extensively using a lot of labour. requires drilling equipment with high autonomy.

It requires two interventions over several months or years for the removal of one tree, and has a visual impact with a potential effect on public opinion.

 

Personal Protective Equipment (PPE)

Gloves, protection equipment against chemical agents.

 

Tools

  1. For Cutting +Injection: pruning knife/saw, squirt bottle, herbicide.
  2. For Drilling + Injection: a  cordless, electric or petrol drill; injection equipment, herbicide.

Security

Specific training to handle the herbicide is needed.

 

Maintenance

Maintenance of PPE and the equipment for herbicide application.

This post is also available in: Portuguese (Portugal)