English ivy is an undeniably attractive plant with glossy green leaves and a dense growth habit. It has, unfortunately, the habit of straying out of gardens and into forests, overrunning acres of land and climbing into trees, sometimes covering them completely. Though removal by digging will eventually kill it, herbicides such as glyphosate, sold under the brand names Roundup, Accord and Rodeo, aid control in large areas.
Glyphosate, the active ingredient in Roundup, is a chemical with low toxicity to humans and animals. It is a non-selective herbicide that kills all plants it contacts if applied in great enough concentration and at the proper time of year. It is a systemic chemical that is absorbed through the leaves and soft stems then transferred to the roots and other tissues. Glyphosate is broken down fairly quickly in the soil, though the time needed varies according to the temperature, and, since it binds to soil particles, does not leach into groundwater. There is some evidence of chronic health effects if exposure continues a long period of time.
Though called English ivy, this plant, Hedera helix, is native to much of Europe and western Asia. It is an evergreen vine that clings to walls, tree trunks and just about anything else by rootlets that sprout from the stem as it grows upward. The leaves are lobed on young stems but when the vine becomes mature the leaves change to simple oval shapes that surround the clusters of small greenish flowers. The fruit is a purplish berry about 1/4 inch in diameter. When the vine spreads over the ground, the stems root and send out new shoots at frequent intervals. It makes such a dense cover that other vegetation, including valuable native plants, are destroyed.
Ivy can be difficult to control both because of its ability to seed prolifically, because the rooted stems can re-sprout, and because of its ability to covered large areas. A systemic herbicide like Roundup will kill all tissues, preventing regrowth, and can be sprayed to cover an extensive infestation quickly.
The effectiveness of Roundup, however, varies according to the season, whether the plants are actively growing or not and the air temperature.
The presence of valuable ornamental or native plants around and beneath the ivy will also affect your decision to use Roundup. All plants will be killed and, because it is a systemic, even roots of nearby trees and shrubs may absorb the herbicide.
Roundup is most effective as new growth begins in the spring, when there are three to five new leaves. Any stems climbing into the tree canopy should be cut since spraying upward is both difficult and potentially dangerous. Follow all directions on the label and consult your local extension service for advice on the best time to spray in your area.
While glyphosate has a fairly low toxicity, it is still a potentially dangerous substance and care should be taken to avoid contact. Use gloves and eye protection at all times.