Buddleia
Buddleja davidii
DESCRIPTION
Buddleja is another of those pretty and exotic garden plants that have escaped to become a serious pest weed in large parts of NZ. It’s originally from China.
It’s a perennial shrub growing quite quickly up to about 3 metres tall. It forms dense thickets once established.
It flowers in summer, producing slender cone-shaped clusters up to 30cm long of purple to mauve flowers that are individually about 5mm in diameter. The flowers are orange inside and are densely packed on the cluster.
Flowering is followed by the production of cylindrical seed capsules up to 10mm long. The seeds are spread by water, wind, and dumped vegetation.
Leaves are slender and willow shaped, and up to 20cm long by 8cm wide. They have a pointed tip, and are finely toothed. The leaves are green and hairless on top and white-grey beneath with a hairy covering.
Buddleia is a multi-stemmed plant. Young shoots on the stems are bluntly angled off the main stem and clad in soft woolly hairs that are easily rubbed off.
The preferred habitat is roadsides, forests (including forestry blocks), riverbeds and riverbanks, and waste areas. It establishes quickly and is extremely tolerant of soil types, temperature range, moisture range and light conditions. Dense stands of buddleia can block waterways and alter water flow, resulting in silting and flooding.
Distribution is NZ-wide, and it is especially common in the North Island and upper half of the South Island. In some regions, buddleia is subject to Pest Plant Management Strategies.
PHYSICAL CONTROL
Small plants can be dug out by hand, but once buddleia reaches maturity it’s rarely a practical, nor a tolerable proposition to dig it out.
HERBICIDES TO CONTROL BUDDLEIA
Herbicides for the Cut stump method to Kill Buddleia
Cut stems low to the ground with a horizontal cut. Apply 1 part G-360 GLYPHOSATE in 3 parts water, or 1 part G-540 GLYPHOSATE in 4 parts water, or 1 part Granny Herbicide in 5 parts water) direct to the fresh cut surface.
Stem Drilling herbicides to kill Buddleia
In large specimens, drill downward-angled holes into the sapwood low on the stems and fill with G-360 GLYPHOSATE, or G-540 GLYPHOSATE, or Granny Herbicide mixed as above, or with GrassMate undiluted.
The same mixtures can be applied to angled cuts made with axe or machete into the sapwood, low on the stems, ensuring that the plant is not totally ringbarked.
Herbicide Sprays to Kill Buddleia
The best time to herbicide spray Buddleia in New Zealand is February to April
- G-360 GLYPHOSATE at 100ml/10L water, or G-540 GLYPHOSATE at 70ml/10L water, or Granny Herbicide at 45g/10L water. In each case add SprayWetter at 10ml/10L water.
- GrassMate at 90ml/15L water by knapsack, or 250ml/100L water by handgun. Add SprayWetter at 10ml/10L water.
- MSF600 at 5g/10L water, plus SprayWetter at 10ml/10L water.
Cut'n'Paste Herbicides to Kill Buddleia
- Cut the weed down to about 2cm above a node and dispose of cuttings appropriately.
- Take your bottle of Cut'n'Paste Bamboo Buster, hold it upside down and gently squeeze a layer of Bamboo Buster glyphosate gel onto the whole surface of the cut stem from the edge to the centre.
- Leave it to die off.
- For the best effects paste the Cut'n'Paste Bamboo Buster onto the Bamboo immediately after cutting
Buddleia will re-establish itself readily from the seed bank in the soil. Permanent control by any method will need to be followed-up twice a year for several years to achieve lasting success.
