Environment

Buddleia flower. (c) Jonathan Boow, Auckland Regional Council Other names:
Butterfly bush, summer lilac

Scientific name:
Buddleja davidii

Status:
Buddleia is currently under surveillance as a weed of concern in Northland.

What does it look like?

Buddleia is a deciduous, multi-stemmed shrub that grows to over three metres tall. Stems are bluntly angled and clad in tufts of easily removed soft, woolly hair.

Buddleia bush. (c) Jonathan Boow, Auckland Regional Council

The leaves are willow-shaped, thin, usually hairless and finely toothed. Flower heads are dense, cone-shaped clusters measuring 30 cms by 5 cms with many flowers, each 5 mms in diameter. Flowers are fragrant, purple or white, and orange inside. It flowers from December to February. Several pink and mauve hybrids and cultivars are also sold.

Seed capsules are 5 to 10 millimetres long.

Why is it a problem?

Buddleia is common throughout New Zealand and forms dense stands in a wide range of habitats. In riverbeds, it can alter water flow, causing silt to build up and flooding problems. Buddleia is extremely ecologically versatile, tolerating a wide range of soils, especially poor soils.

It can tolerate frost, and a wide range of conditions. Thickets establish and grow quickly, and are self-replacing. It invades river beds, streamsides, disturbed forest, shrubland margins and bare land. It reseeds profusely into bared sites and cut stumps will also resprout.

How do I get rid of buddleia?

Pull or dig out small plants and then mulch.

For larger invasions, weed wipe between February and April with 300 millilitres of glysophate per litre of water.

Note:
When using any herbicide PLEASE READ THE LABEL THOROUGHLY to ensure that all instructions and safety requirements are followed.  Where this plant or the stated control methods do not specifically appear on the manufacturer’s product label, there can be no guarantee given by Council or the manufacturers as to the product’s performance. Mention of product trade names implies neither Council endorsement of those products nor criticism of similar products not mentioned.

Biological:

At this stage, the introduction of the biological control agent, cleopus weevil, is in its trial stage for controlling buddleia. It is hoped to have more information available on harvesting opportunities in the near future.

How do I stop it coming back?

Buddleia is a major pest, and it is difficult to prevent reinvasion. Follow-up check and resprays are necessary every six months. Maintain a rolling front for best effect.

More information

For further information or control advice please contact one of our Biosecurity Officers at the Northland Regional Council on 0800 002 004:

• Whāngārei: Sara Brill
• Dargaville: Carl Cooper
• Kaitāia: Doug Foster