Author: TunyaLee Morisawa, Global Invasive Species Team, The Nature Conservancy
- Hedera helix is an evergreen perennial climbing vine that attaches to bark of trees, brickwork and other surfaces by root-like structures that exude a glue-like substance to aid in adherence.
- Leaves are alternate, dark green, waxy, somewhat leathery; extremely variable leaf forms, from unlobed to 3-5 lobed; typically green with whitish veins.
- Flowering occurs in late summer to early fall, typically under full sun conditions; flowers are small, greenish-yellow and occur in globular starburst type inflorescence at tips of flowering stems.
- Fruits are black with a fleshy outer layer and stone-like seeds. New plants grow easily from cuttings or stem fragments that make contact with the soil.
- Ecological Threat
- Hedera helix is an aggressive invader threatening all levels of forested and open areas, growing along the ground as well as into the forest canopy. Vines climb up tree trunks and envelop branches and twigs, blocking sunlight from the host tree’s foliage, impeding photosynthesis. An infested tree will exhibit decline for years before it dies. The weight of vines also makes trees susceptible to blowing over in storms. This plant has been confirmed as a reservoir for bacterial leaf scorch (Xylella fastidiosa), which affects a wide variety of trees.
Hedera helix belongs to the family Araliaceae and is a native of Europe. In its native region, it does not cause significant damage and is highly valued as an important food resource for insects and birds. Brought to North America by colonial settlers, H. helix has become naturalised in the United States and southwest Canada. English Ivy is cultivated in Europe and North America in gardens, landscapes and as house plants. This plant grows easily in many types of soil and in sun or shade. English Ivy is fairly drought tolerant once it is established. Leaves are alternate and simple with the juvenile leaves 3-5 lobed and adult leaves ovate to rhombic. Mature plants will bear greenish-white flowers. The fruit is berry-like and black.
Related species include Atlantic Ivy Hedera hibernica (G.Kirchn.) Carrière, Algerian Ivy Hedera algeriensis Hibb., and Canary Island Ivy Hedera canariensis Willd. These species were formerly included within H. helix but are distinct in morphology, cytology and genetics. Some authors still treat H. hibernica as a subspecies of H. helix.
Poultices for cuts and sores are made from the leaves. However, an allergic reaction can occur in sensitive people. Secondary compounds within the leaves may be natural product pesticides for insects and mollusks.
English Ivy can occasionally outcompete both grasses, herbs and trees, often reducing animal feeding habitats. In warm areas, H. helix can grow throughout the year and probably outcompetes native vegetation that is dormant during the winter. In Australia, English Ivy is found in disturbed areas of the forest. Seeds are often spread into these areas by birds or other animals.
Cutting is successful with persistence but does not always kill the plant. However, the use of cutting and then applying a herbicide may provide better control.
Using a shovel to remove plants provided immediate control with little regrowth. Weeding plants by hand or with pliers successfully allowed regeneration of most native species in Australia. Do not leave the pulled plants on the ground; they can continue to grow. If removal of the plants is not possible, place the pulled plants on a wooden platform to dry and decompose.
Immediately control English Ivy that is growing up trees by cutting the vine at waist height, loosening the vine around the limbs and removing the roots. If the root can not be removed by hand, strip the bark and notch the exposed section of the vine. Paint on an undiluted herbicide such as glyphosate. If English Ivy is growing on treeferns, take care that all pieces of the ivy are removed. The growth of H. helix can be sustained by the fibrous nature of the trunk.
A wax layer on the leaves often prevents herbicides, especially hydrophilic compounds such as glyphosate, from permeating the leaves.
In container pots, two applications, one month apart, of 2,4-D (Weedar 64®) applied at 1.1 kg/ha (1.0 lb/A) provided control of English Ivy. Two applications of glyphosate (Roundup®) applied at 4.5 kg/ha (4.0 lb/A) effectively inhibited regrowth and provided some control. Regrowth but reduced shoot weight was observed with one treatment of 2,4-D and glyphosate at the rates stated above. The same observation was noted for one or two applications of glyphosate applied at a lower rate of 2.2 kg/ha (2.0 lb/A). Regrowth occurred with plants sprayed with one or two applications of Dicamba (Banvel®) or triclopyr (Garlon®) at the rate of 0.6 kg/ha (0.5 lb/A).
In another study, an application of glyphosate (25% solution) provided good control. Cutting (using a nylon cord weedeater to cut to the stem surface just before treatment) followed by a 25% solution of glyphosate also provided control of English Ivy. Excellent control of H. helix that had been cut and then sprayed was achieved with a 2% solution of 2,4-D. A lower rate of glyphosate (2% solution) and cutting provided only slight control. Glyphosate only (2% solution) did not control English Ivy. The herbicide triclopyr or mowing provided no control. Control evaluations were made 1 year post-treatment.
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