ECOLOGICAL THREAT
English ivy is a vigorous growing vine that impacts all levels of disturbed and undisturbed forested areas, growing both as a ground cover and a climbing vine.
As the ivy climbs in search of increased light, it engulfs and kills branches by blocking light from reaching the host tree’s leaves. Branch dieback proceeds from the lower to upper branches, often leaving the tree with just a small green “broccoli head.”
The host tree eventually succumbs entirely from this insidious and steady weakening.
In addition, the added weight of the vines makes infested trees much more susceptible to blow-over during high rain and wind events and heavy snowfalls. Trees heavily draped with ivy can be hazardous if near roads, walkways, homes and other peopled areas.
On the ground, English ivy forms dense and extensive monocultures that exclude native plants.
English ivy also serves as a reservoir for Bacterial Leaf Scorch (Xylella fastidiosa), a plant pathogen that is harmful to elms, oaks, maples and other native plants.
LINKS FOR MORE INFORMATION (updated 11/11/23)
The Ivy Files (Portland Parks)
Ivy Removal in a Home Landscape (OSU Extension)
Controlling English Ivy in the PNW (by the Nature Conservancy)
English Ivy Management Resource Packet (Oregon Dept of Agriculture)
