Frank Williams
Adams County Master Gardener

Invasive species (plants, insects, and animals) have been a part of the American landscape for decades. But their spread in recent years has been truly monumental including virtually all sections of the country. This article stems from a contact I had with a friend in Adams County at whose home I observed massive amounts of English ivy invading his wonderfully wooded property and climbing even large trees in the area. Today we will deal only with those invasives which take over landscapes.

What is an Invasive Plant?

Basically, an invasive plant is one which can thrive and spread aggressively, often outside its natural range and under a wide variety of environmental conditions. Those that colonize in a new area have an ecological advantage since the insects, diseases and foraging animals which control them in their natural range may not be present to the same degree in a new environment.

Some Typical Examples

The English ivy mentioned above is but one of a number of invasive plant varieties which frequent our area. Some other prime examples include exotic honeysuckle, crown vetch, Japanese knotweed, mile-a-minute, and purple loosestrife. All share the ability to establish themselves easily, spread quickly, and strangle other desirable native indigenous plants over time.

Consider the Damage

As mentioned above, invasive plants can disrupt, or even destroy, natural habitats. Sensitive ecosystems such as sand dunes and wetlands are especially vulnerable. In areas such as national parks, even visitor foot traffic can create a void and become quickly invaded. Purple loosestrife, for example, can be observed where folks have created footsteps in the damp ground. Native plants and trees destroyed by the invasives may take hold again as an invasive groundcover prevents new germination. In Montgomery, Maryland, a group of volunteers called Weed Warriors have been enlisted to do battle in an effort to identify and remove or destroy invasive plants. Now here is a "war" we can all support!

In your own yard, think of the damage that English ivy and other vines can do, not only your plants, but also to masonry, gutters and any place where roots can grow and take hold.

What Can You Do?

In an article published in the Old House Journal, Kathleen Fisher writes about "whacking wicked weeds." In essence, she advises that homeowners get rid of them by cleaning the yard totally of invasives, cutting them back and removing remaining debris off the home’s facing and around desirable plants.

From the United States National Arboretum, I found some other suggestions in the August, 2004 release as follows:

• Check with your local resources (Pennsylvania State Extension Service, Master Gardeners) With respect to which plants are invasives, learn how to identify them;
• When making landscaping plants, use only non-invasive plants in the development of that plan;
• Be especially careful when landscaping your property if it borders on open, local, state, or national park areas;
• Use herbicides carefully as a last resort to remove invasive plants in a way that does not do damage to native plants or other desirable plants in your landscape;
• Make others in your neighborhood aware of invasive plants and how to identify, remove, or control them.

Summary

If you have some invasives in your yard (as I do with English ivy), take measures to remove or manage them carefully. Our ivy, for example, grows over a patio fence with a pleasing, cascading effect. But regular manicuring and serious cutting away the overgrowth was absolutely essential during this wet spring and summer. You can help your yard and environment by becoming aware of the problem and assisting others to deal with it. Be pro-active in this crusade. The invasives are indeed here and becoming more aggressive each year.

Read other articles on ecological gardening & native plants