What does it look like?
English ivy is an evergreen climber that can spread along the ground or climb trees, walls, and other structures. Mature plants have woody stems with alternately arranged, shallow lobed leaves up to 3 x 15cm long. It produces numerous tiny yellowish-green flowers from March to May. Berries are deep purple to black, 5-8mm diameter, with 2-3 seeds per fruit.
Preferred habitat includes roadsides, native forest, riparian zones and cliffs. It often escapes from garden groundcover plantings. English ivy is shade, frost and drought tolerant, but prefers damp, fertile soil.
Why is it a problem?
English ivy can invade and dominate woodlands, reducing regeneration of native forests. Increasing canopy openness promotes further invasion of ivy climbing up trees with increasing impacts on fitness of existing trees. In particularly bad cases, it can strangle entire trees leading to canopy collapse.
English ivy is pollinated by birds and insects and is linked to increased wasp visitation rates. Seeds are predominantly dispersed by birds, but the plant is also palatable to deer and goats. Deliberate planting and the dumping of garden waste increases its spread.
Control methods
Physical control
Cut off ivy growing up trees and remove all roots and stems growing along the ground. Dry thoroughly, take to transfer station or alternatively burn or bury deeply.
Herbicide control
Cut plants off at ground level and paint stumps immediately with 5g metsulfuron-methyl (600g/kg) per 1L water. Ensure all stems are cut and treated and leave upper plant material to die. Or
Spray smaller areas in summer with 5g metsulfuron-methyl (600g/kg) + penetrant per 10L water. Do not spray ivy on tree trunks as this is likely to kill the tree.
Treating ivy growing on other plants is difficult and may endanger the supporting plants. Check for resprouting stumps and new plants arising from stem fragments and seeds.
CAUTION: When using any herbicide or pesticide, PLEASE READ THE LABEL THOROUGHLY to ensure that all instructions and safety requirements are followed.
Related links
http://www.nzpcn.org.nz/flora_details.aspx?ID=4061
