Is the English Ivy covering the unattractive fence in my backyard really an environmental villain?

Is the English Ivy covering the unattractive fence in my backyard really an environmental villain?

—Perry Pitcher, Seattle, WA

English Ivy is everywhere across the North American landscape, largely because it is an attractive, hearty and fast-growing groundcover that can hide other unsightly landscape and structural elements. But the ugly truth about this beautiful but non-native plant is that it aggressively invades new territory, often choking out native plants in the process.

According to the Seattle-based Ivy Off Urban Trees (IvyOUT) program, English Ivy is quite hazardous to trees it may colonize, weakening the bark by keeping it constantly damp, and blocking sunlight, inhibiting photosynthesis. Also, by reducing the airflow around the trunk, ivy makes trees more susceptible to wind stress and disease. As the vines grow higher and higher, they can eventually choke the life out of a tree.

Beyond trees, the plant tends to overwhelm other native flora, creating “ivy wastelands” devoid of biodiversity—except for the rats, slugs, mosquitoes and other pests it may harbor. It often spreads out of backyards and into parklands and other green spaces, both by climbing and through seed dispersal by birds.

Native to Europe, English Ivy was first introduced to North America as an ornamental garden vine in the 19th century. Like other invasive non-native species brought to the “New World,” it had no natural predators or pests to keep it in check, and as a result quickly gobbled up habitat meant for native plants. While expensive government programs have helped halt the spread of a few well-known and intensely feared non-native species such as Zebra mussels and Purple Loosestrife, English Ivy continues to sprawl across the country, not only unabated, but often encouraged by unaware gardeners.

According to the Department of Environmental Services in Arlington, Virginia, ivy should be removed from any and all trees by cutting the vines at ground level and again several feet up any affected trunks. The remaining ivy should be peeled off, but with care so as not to strip off any bark. Beyond controlling English Ivy in your own backyard, you can be a good neighbor by also making sure it does not spill over onto adjacent land.

If you choose to remove your English Ivy completely and replace it with something more benign, the website eNature.com, run by the National Wildlife Federation, enables you to search a free database of native plants by simply entering your state and the type of plant (i.e. vine, wildflower, etc
) you seek. Local nurseries can also usually help you choose a good native replacement for English Ivy.

CONTACTS: Ivy Off Urban Trees, www.ivyout.org; Federal Invasive Species Website, www.invasivespecies.gov; eNature.com Database, www.enature.com/native_invasive/natives.asp.