English Ivy

Hedera helix ‘Baltica’, ‘Pittsburgh’, and ‘Star’; Hedera Hibernica ‘Hibernica’

Class C Noxious Weed

General

Native to north temperate and subtropical zones of Europe and Asia.
There are more than 400 different English ivy cultivars, which vary in leaf shape, size, color and habit. There are four listed cultivars of English ivy which are derived from two species Hedera Hibernica and Hedera helix. These have the greatest invasive potential and should not be sold or purchased.
- Native plant alternatives include salal, low Oregon grape, and kinnikinnick.
Outcompetes native plants and inhibits regeneration of understory plants.
Kills overstory trees by shading out foliage and suppressing the host tree. As the tree begins to die the open crown allows for additional ivy growth, adding greater weight to the tree and increasing storm damage.
Changes the natural succession patterns of forests.
The sap of the stems can cause skin irritations and rashes to sensitive individuals.
Long lived, plant samples estimated to be greater than 400 years old. Vines can grow up to 99 feet long, with stems reaching one foot in diameter.

Identification

Woody, evergreen, perennial vine or shrub.
Two distinct growth phases: Grows as a vine (juvenile form) or a shrub (adult form).
English ivy matures and produces flowers and fruits when it begins to grow vertically (Understanding this life history characteristic is key to its control).
Flowers are greenish-white and occur in umbrella-like clusters in the fall. Fruits are dark blue to black berry-like drupes that mature in the spring.
Leaves are alternately arranged, leathery, with long petioles. Juvenile leaves are deeply 3 to 5 lobed and 1.6 to 4 inches long and wide. Adult leaves are primarily un-lobed leaves and egg to diamond shaped.
Young stems have hairs while older stems are hairless. Juvenile form produces adventitious roots that allow vines to anchor and climb vertical surfaces. Stems growing along the ground also produce adventitious roots.

Photos

Habitat

Grown in landscaped areas, often escapes to adjacent forests and natural areas from sea level to 3,300 feet in elevation.
Grows in a variety of soil types and light conditions. Generally considered a shade plant, but grows in both shade and sun.
Habitats include woodlands, forest edges, riparian areas, hedgerows and disturbed habitats.

Reproduction and Spread

Reproduces by seed (adult form) and vegetatively.
Since it is evergreen it can photosynthesize year-round.
Initial colonization is by seed, dispersed by birds; on average 70% of ivy seeds are viable and plants produce thousands of fruits per year, each fruit has 4 to 5 seeds.
Once established ivy spreads rapidly by vegetative stem growth; stem and root fragments left on moist soil can resprout and form new plants.

Control

Prioritize actions based off these recommendations:
- Start by controlling ivy in canopy, climbing ivy only produces fruit; remove to prevent spread by seed.
- Work from least infested areas moving towards most infested areas, drawing a clear perimeter line around the infestation.
Plants can successfully be pulled by hand or dug up. Combine pulling with loppers to do a pull-cut combination. Fall through spring is a great time as plants are easier to remove from ground when soil is moist.
Pile up ivy on a tarp or “life raft” of tree limbs to avoid contact with soil and prevent re-establishment. Leave piles on-site to save unnecessary landfill space.
To remove plants climbing on trees, cut around the base of the tree at waist to chest height (around 4 feet high), pull lower parts of the stems off the tree, and remove all ground ivy making an ivy free circle around the base of the tree, extending two feet from the tree.
- It will take time but the leaves above the cut stems in the tree will slowly die and fall off.
- A pry bar, hand saw, axe or small chainsaw may be necessary to cut and remove large vines.

Herbicide Control

Due to the waxy outer surface of its leaves, ivy is not easily controlled with herbicides.
Herbicides may be effective containing the active ingredients:
- Triclopyr (Selective herbicide):
  - Foliar Application: Apply 2 to 5% solution to leaves and stems in summer to fall.
    - Alternatively, before spraying, use a string weed-whacker to cut leaves and young stems, then immediately spray plants.
  - Cut Stump Application: Apply 33 to 100% concentrate solution to freshly cut stems; apply anytime of the year as long as the ground is not frozen.
- Glyphosate (Non-selective, non-residual herbicide):
  - Apply 2 to 4% solution foliar application, 25% solution for cut stump application; follow methods and timing for triclopyr.
- Imazapyr (Non-selective, residual herbicide):
  - Apply 1 to 2 % solution foliar application, 20% solution for cut stump application; follow methods and timing for triclopyr.
Control areas should be monitored for a number of years, for effectiveness, regrowth and reestablishment.

Works Cited

Perennial Peavine Profile. (n.d.). Oregon Department of Agriculture (Noxious Weed Control Program). Retrieved from https://www.oregon.gov/ODA/shared/Documents/Publications/Weeds/PerennialPeavineProfile.pdf
BEST MANAGEMENT PRACTICES Everlasting Peavine(Lathyrus latifolius) and Flat Pea (Lathyrus sylvestris) (Family—Fabaceae—Pea Family) . (n.d.). JEFFERSON COUNTY NOXIOUS WEED CONTROL BOARD. Retrieved from https://www.co.jefferson.wa.us/DocumentCenter/View/2957/Peavine
DiTomaso, J.M., G.B. Kyser et al. 2013. Weed Control in Natural Areas in the Western United States. Weed Research and Information Center, University of California. 544 pp.