Attacking Invasive Species

Pulling weeds is fun.

Really–we’re not making this up. Tearing out non-native, invasive plants is productive, and provides protection for parks, plus the act of ripping out an invader provides an emotional rush. The repetition of pulling weeds, however, brings the realization that this might be a long and–if not done quickly–losing battle.

The Fairfax County Park Authority wins some battles before the enemy establishes its stronghold. The Northern Virginia agency has initiated an Early Detection, Rapid Response (EDRR) program to identify and remove small infestations of invasives before they become serious problems.

Invasive plants rarely are overnight sensations despite fanciful names like “mile-a-minute” that are, thankfully, an exaggeration. There is a time when invasive plants can be removed, not just limited.

Is It Serious Yet?

A serious infestation begins with one or two individual plants that happen to find ideal conditions. Imagine if someone could recognize that original loner as the area’s next kudzu or multiflora rose? Wouldn’t it be easier to remove that one plant than face a tangled hillside or a forest permeated by invasive-plant species?

EDRR is like a treasure-hunter seeking something new, rare or unusual. In Fairfax County, treasure-hunters seek plants that are not native to Virginia. The reward is keeping them out of natural areas.

The program is based on the Early Detection & Distribution Mapping System (www.eddmaps.org). Other valuable sources of information include the work of botanist Les Mehroff and the University of Connecticut’s Invasive Plant Atlas of New England (http://invasives.uconn.edu/ipane) and The National Invasive Species Council (http://invasivespecies.gov/global/EDRR/EDRR_index.html).

Two-Pronged Attack

EDRR consists of two parts that are separate, but equally important.

Part one asks, “How do you find one plant in the Hundred-Acre Wood?” Early detection is finding an invasive plant that you don’t know is there but you do know that putting off a problem can have awful consequences.

The silver bullet is knowledge–knowing which plants might be a problem. That’s a two-step process. Step one is to become familiar with the habits of the native plants in the region. Step two is developing the ability to recognize something that isn’t part of step one.

This is preparation. In this case, preparation is learning:

• What you have

• What’s out there in nearby habitats

• What could be moving toward your region

• What could become a threat.

In our mid-Atlantic location, buffered by the Chesapeake Bay and an ocean on the east and by mountains on the west, we keep an ear open for reports of plants that are migrating north or south from other Atlantic Coast regions.

In the past year, we have found three new threats. We had an unnerving run-in with the spiny prickly castor-oil tree (Kalopanax septemlobus), which can reach 90 feet and sports thorns about ½-inch long. It had been reported once before in Fairfax County. We’re keeping an eye out for more.

Harmless-looking wavy leaf basket grass (Oplismenus hirtellus ssp. undulatifolius) might look like a nice addition to a forest ecosystem, but native forest floors are supposed to be a kaleidoscope of flowers, grasses and leaf litter–not a monotonous green carpet. This species has spread to hundreds of acres in nearby Maryland and to a few preserves on our side of the Potomac River in Fairfax County. We’ve not spotted any on parkland.

Two reports of marshdew flower, a.k.a. wart-removing herb (Murdannia keisak), caught our attention. This invasive plant is widespread in southern coastal Virginia, but it’s not common in Fairfax. Like other aquatic invasives, control of this East Asia invader is difficult and requires an herbicide. Getting a handle on the distribution of M. keisak is a priority for our program.

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