Japanese honeysuckle

Japanese honeysuckle is a scrambling, branched perennial evergreen climber. It smothers native vegetation and hosts several pathogens in orchids.

Description

• Stems are tough, brown, flexible and smooth.
• Leaves are dark green, opposite and lance-like.
• Flowers are fragrant, paired and white to yellow and occur in spring to autumn.
• Fruit is hard and green, ripening to soft black berries.
• Seeds dispersed by birds. Vegetative spread from fragmentation.
• Human-mediated dispersal through dumping of garden waste and contamination of machinery.
• Habitats include disturbed sites, gardens, hedgerows, forest edges, plantations, shrublands, canopy gaps, roadsides, wastelands, and bare ground.

What you need to know

Forms dense mats, smothering native vegetation. Harbours mice and facilitates other invasive plants. Hosts several pathogens in orchards, overgrows young plants and inhibits pine growth through allelopathy in forestry plantations.

Management approach

Japanese honeysuckle is declared an unwanted organism by the Ministry for Primary Industries (MPI) because it is capable of causing harm to the natural environment, physical resources or human health in Aotearoa/New Zealand.

These species pose a high risk to our environment, economy, recreation, and cultural values.

Rules

Any species declared a pest, including unwanted organisms, cannot be sold or be in a place where plants are being sold. Pest plants cannot be propagated, bred, multiplied, communicated, released, caused to be released, or otherwise spread.

Consider removing this invasive species from your property and consult your local council for appropriate disposal. Consider lower-risk alternatives for your garden, such as native plants.

Control

Site management

Cut and pull vines away from desirable trees and native plants before foliar spraying. Follow up treated areas three times per year. Encourage natural regeneration of native plants or replant treated areas where possible after two to three treatments to establish dense ground cover and minimise reinvasion.

Physical control

Cut vines and leave upper stems to die in trees or dig out.

Plant parts requiring disposal: All parts (except vines if left to die in trees).

Contact your local council for appropriate disposal locations.

Chemical control

No qualifications: For small infestations: cut stump and paste freshly cut base of stems with metsulfuron gel.

Certified handler/experienced agrichemical user: For small infestations: cut stump and spray freshly cut base of stems with 1g metsulfuron-methyl per 1L of water or cut vines at waist height and foliar spray vines on the ground with 0.5g metsulfuron-methyl per 1L of water.

For medium to large infestations: cut vines at waist height and foliar spray vines on the ground with 5g metsulfuron-methyl per 10L of water and 20ml penetrant.

For infestations amongst desirable species: foliar spray with 50ml clopyralid per 10L of water and 20ml penetrant (not for use in home gardens).

Caution: When using any herbicide or pesticide please read the label thoroughly to ensure that all instructions and safety requirements are followed.

Biological control

Look out for Honshu white admiral (Limenitis glorifica) and Japanese honeysuckle stem beetle (Oberea shirahatai).