What does it look like?
Buddleia is a woody and deciduous ornamental shrub that grows up to 3m tall. The small mauve/purple flowers are orange inside and form distinctive cone-shaped hanging clusters between December and February, followed by seed capsules 5-10mm long.
The plant invades riverbeds, stream sides, disturbed areas, shrubland and forest margins. It tolerates a wide range of soils and temperatures, prefers wet to moderately dry conditions and is resistant to wind and damage. It can grow in shade or open areas, but seedlings require high light levels.
Why is it a problem?
Buddleia establishes and grows quickly, forming dense thickets in a wide range of habitats, excluding other plants. It reproduces vegetatively through regeneration from suckers, as and produces huge numbers of highly viable seeds. All of these factors make it very successful in out-competing other native species.
Control methods
Physical control
Hand pull or dig out small plants and leave on site to rot down.
Herbicide control
Cut stumps and apply: Glyphosate 250ml per 10L water; Or Tordon Brushkiller 250ml per 10L water. Or
Spray February-April with Glyphosate 10ml/L water; Or, Metsulfuron-methyl (600g/kg) 5g per 10L water; Or Tordon Brushkiller 6ml/L water; And/or,
Young plants can be sprayed late summer to autumn with glyphosate 10ml/L water; Or metsulfuron-methyl 5g per 10L water.
CAUTION: When using any herbicide or pesticide, PLEASE READ THE LABEL THOROUGHLY to ensure that all instructions and safety requirements are followed.
Biological control
The buddleia leaf weevil was released in the Wellington region in 2007 and is becoming widespread. Affected plants can be completely defoliated.
Related links
https://www.landcareresearch.co.nz/discover-our-research/biodiversity-biosecurity/weed-biocontrol/
http://www.nzpcn.org.nz/flora_details.aspx?ID=3582
http://www.nzflora.info/factsheet/Taxon/Buddleja-davidii.html
https://www.weedbusters.org.nz/what-are-weeds/weed-list/buddleia
