To control weeds or not?

Why we need weed control

Weed control is just part of what is needed to protect New Zealand's natural areas.

The purpose of environmental weed control is not only to kill weeds but also to restore forests, shrublands or wetlands, and to help protect threatened plants and animals.

Weed control is a long-term commitment. Most weeds reinvade very quickly after control, so it is important that your weed control is well planned. It is better to do a small area effectively and go back the next year, control any regrowth, then move on to a new area. You need to pick a battle you can win.

Weeds need to be controlled sooner rather than later. Once weeds are established and become bigger and are dominant, removal and restoration becomes more difficult and more expensive.

Before you decide whether or not to control weeds, collect some information and ask lots of questions. Find information online, from local councils and DOC staff.

The Weedbusters website has lots of good information.

Assess the problem

Find out if the weed is really a problem or would killing it make matters worse. Weeds thrive in disturbed sites – the weed that reinvades could be worse than the weed that is there now.

Gather the following information:

• What native plants and wildlife are present
• What weeds are present
• The impacts the weeds are having on the native plants and wildlife. Not all weeds are created equal. Some weeds will be more of a problem than others.

Ask the following questions:

• What will happen if you do nothing? Is that acceptable?
• Is it possible to kill the weed?
• Can the regrowth be managed long term?
• What is the likelihood of the weed growing again?
• Where are the sources? 
• What can be done to avoid reinvasion? (You may need to work with your neighbours.)
• How are the seeds dispersed e.g. wind, water or by birds?
• How does the weed reproduce – by seeds and/or cuttings (vegetative)?
• How long does the weed take to mature and produce seed?
• How quickly does the weed establish and grow?
• What conditions does it like to grow in, eg lots of light, little light or in frost areas?
• Is there a native plant seed source?
• If not you may need to consider replanting natives. Is this an option?