Weed control in forestry

Control weeds

Controlling weeds is an important part of looking after your forest. Invasive weeds can:

• steal nutrients needed by trees
• restrict the growth of saplings
• harbour pests that may be harmful to your trees.

Regular inspections are the best way to find and deal with invasive weeds before they become a problem.

The Department of Conservation has a guide on how to control weeds.

Wilding conifers

Conifers are trees which spread from cones, such as pine trees. A wilding conifer is an unwanted conifer that has spread naturally, instead of being planted by foresters. Wilding conifers have become a threat to New Zealand's native landscape, high country farming and biodiversity.

Gorse

Gorse is a scrub weed, originally introduced as a form of farm hedging. It is easily distinguished from other pest plants by its thorny leaves and bright yellow flowers.

Gorse can spread quickly over large distances. The seeds disperse explosively, spreading across many metres. They can also be picked up by the wind and by the fur or fleece of passing animals.

Gorse grows quickly and densely and can outcompete pasture and forestry for nutrients, water, light and space. It can regrow quickly from any remains left after burning or cutting, making it hard to control and even harder to eliminate. Biological methods (animals and insects) seem to be the most effective control methods.

Gorse plants dry out over summer, increasing the risk of fires. 

Exotic plants

Smothering vines can affect forest canopies. These include banana passionfruit, bomarea, Chilean flame creeper, climbing spindleberry, ivy, Japanese honeysuckle, old man's beard, mothplant and wonga wonga vine. The New Zealand Plant Conservation Network and Weedbusters can help you identify these.