Lauren R. Stevens: Milfoil warriors should look to Cayuga

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WILLIAMSTOWN — A decade or two ago the Hoosic River Watershed Association arranged for the Cheshire Lake homeowners to meet a Middlebury College alum who, with other students and their professor, had come up with a biological way of controlling Eurasian milfoil. The hero in the scenario was a weevil with the moniker Euhrychgiopsis lecontei, which occurs naturally in some Berkshire lakes and ponds.

Well, the approach was new and relatively untested, and the Chesherites opted to take a different route to controlling an obnoxious weed that is anchored to the bottom, sucks oxygen out of the water and creates a thick mat on the surface, all but denying boat passage. If it looks like something you saw in an aquarium, that may be how it traveled to this country. It drives out native plants and in general degrades the aquatic ecosystem.

Right now some Stockbridge Bowl residents and conservation commissioners disagree on whether chemicals or mechanical harvesting is the second best way of controlling milfoil. All authorities agree that the best way is to catch it early; once it is established, finding any practical method is iffy. Most important is to clean off boats and recreational gear after use.

For any infestation of milfoil beyond what can be plucked by hand and carefully disposed of, a mechanical harvester is probably the most popular approach for lakes in the Northeast and Midwest. It's expensive, though, must be used multiple times in a growing season and, even with care, chewed bits are liable to get away and reseed — perhaps in an area were milfoil had not existed previously.

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According to New York State Invasive Species information, a variety of chemicals can combat milfoil, especially if applied early in the growing season and when the water is still. Some affect other plants and their use can disrupt aquatic life — and human use. For example, 2,4-D (trade names Navigate, Aquakleen and Aquacide) doesn't affect other plants but isn't effective on large areas. Fluridone (Sonar and Avast) can be effective for an entire season but does affect native species. Repeated chemical doses are disheartening and expensive. Most people would prefer not to add chemicals to their lake.

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Scientists are continuing to work on a biological approach. They have tried introducing carp, which unfortunately will turn to milfoil only after they've eaten a lot of the native vegetation. A fungus and numerous non-native insects have been tested.

E. lecontie, in fact, has proved to work well. But when Middlebury students and then EnviroScience Inc, which took over Middfoil, added additional weevils to lakes, sometimes they were effective and sometimes they disappeared. The supposition is that fish ate them. In 2014 EnviroScience discontinued the Middfoil program not, according to its website, because the approach didn't work, but for economic reasons. Other sources of weevils exist, but clearly the approach is chancy.

Another possible savior is a naturalized moth, Acentria ephererella, which feeds on several kinds of plants. It shares, with E. lecontie, credit for cleaning up Lake Cayuga among other lakes in Ontario and New York, apparently without much human assistance. One difference should be noted, though. Many of those lakes may have a low fish population due to acid rain. The limestone in Berkshire County buffers the acidity, so that fish populations are more robust.

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There may not be any sure cure for milfoil, but Lake Cayuga is relatively nearby and thoroughly studied by Cornell University. The milfoil has been controlled and native plants have returned. Far above Cayuga's waters might be a good source of scientific advice for Berkshire lakes.

At least that's how it looks from the White Oaks.

A writer and environmentalist, Lauren R. Stevens is a regular Eagle contributor.


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