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Weed Information

Weed Information Sheet

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Japanese Honeysuckle

Botanical Name

Lonicera japonica

Family

Caprifoliaceae (honeysuckle) family

Where is it originally from?

Japan

What does it look like?

Vigorous evergreen (semi-evergreen in cold districts) climber with long, tough, wiry stems that twine clockwise, are purplish and hairy when young, and turn woody as they mature. Leaves (3-12 x 2-6 cm) are in opposite pairs on the stems, are shiny dark green (occasionally yellowish) on the top and lighter green underneath, and are wavy-edged to lobed when produced in cold climates, otherwise they are entire. Pairs of 2-lipped, sweetly scented tubular white flowers (2-5 cm long) that age to yellow are produced from September to May, and are followed by egg-shaped, glossy black berries (5-7 mm diameter) in colder parts of NZ, each containing seeds (2mm).

Are there any similar species?

Many similar Lonicera species are cultivated, and hybrids and cultivars of L. japonica. L. pericyclamineum and L. x americana are both found in the wild.

Why is it weedy?

Climbing, smothering habit. Forms dense, long-lived masses. Tolerates moderate-shade, frost, salt, damage, wet or dry, most soils, high to low temperature. Very long stems layer profusely, moderate-fast growth rate. Poor seeder.

How does it spread?

Birds, possibly possums. Roading machinery, dumped vegetation, soil and fill. Roadsides, wasteland, plantation forest, hedges, shelterbelts.

What damage does it do?

Climbs over and smothers most plants from ground to medium canopy. Can cause canopy collapse and subsequent invasion of grasses or ground vines. Provides support for faster growing weedy vines (eg morning glory, moth plant).

Which habitats is it likely to invade?

Forest margins, shrublands, disturbed forest, coastal areas, river systems, wetland margins, fernland, and inshore islands.

What can I do to get rid of it?

  1. Dig out small sites (all year round). Dispose of roots and stems at a refuse transfer station, burn or bury deeply.
    2. Cut and paint stump: within 10-15 minutes of cutting, paint cut surfaces with a liberal dose of triclopyr 600 EC (100ml/L) or Yates Woody Weedkiller (200ml/L).
    3. Cut and paint stump (all year round): metsulfuron-methyl 600g/kg (5 g /L) or Tordon Brushkiller (200ml/L) or picloram gel. Leave vines in trees to die, dispose of cut stems at a refuse transfer station, burn or bury deeply.
    4. Cut the vines at a convenient height in winter and spray the regrowth in the spring with glyphosate (10ml/L + penetrant) or metsulfuron-methyl 600g/kg (2g/10L + penetrant).
    5. Spray (summer-autumn): glyphosate (10ml/L) or metsulfuron-methyl 600g/kg (5g/10L + penetrant) or clopyralid (50ml/10L) or Tordon Brushkiller (60ml/10L).

What can I do to stop it coming back?

Hard to kill. Stumps resprout, stems layer, but very shy seeder, so sites usually remain clear after treatment. Check for new sprouts 6-monthly until clear. Replant bared areas if seedlings are a problem.

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