From what I can tell, I live in an area of woodland the ecologists call a hemlock forest.

In other words, a large percentage of the trees on my little acres in Troy are hemlocks, together with spruce, oak, yellow birch, and red and sugar maples. Mostly red, in my place.

In the spring we have forest plants such as Canada mayflowers and starflowers, and there’s hardly any grass that I did not plant myself in my ledgy, acidic soil. Instead, mosses are trying to take over the shady parts of the world. We’re on a slope with a level area where the house sits that doesn’t drain efficiently, which is good for the well and bad for the driveway.

Surrounding the house is a mix of other firs and hardwoods, including white pines — one of them ancient — cedars, white ash, popple, at least one ironwood tree, a black cherry or two, a few apple trees left over from when this hillside was a cow pasture, white and gray birch, and smatterings of beeches.

There used to be an elm tree, maybe 30 feet high, standing guard with the hemlocks and maples over the shed. But one summer it suddenly died. I never had a forester look at it, but my guess is Dutch elm disease got it, the killer fungal ailment that came to North America from Europe in the 1920s. The nearest elm I know of now is across Route 9 in the Mount Holly Cemetery.

There is not a chestnut tree within miles of us, as far as I know. Three billion to 4 billion of them got wiped out by the chestnut blight, another fungal infection that was first noticed in New York in 1904 and in Maine in 1916. So I haven’t had any chestnuts to worry about in the past 20 years, and only one elm.

But the largest beech tree on my side of the tumbledown stone wall through the woods that roughly marks the property line is pretty clearly sick. It has diglike marks all over the upper part of its bark, which on its progeny all around it is smooth gunmetal gray. The tree, I am sorry to conclude after doing some reading, appears to be suffering from beech-bark disease.

This ailment is caused by a fungus, too, but it takes longer to kill individuals, so its effect doesn’t seem as radical as the Dutch elm or chestnut blight. But many beech trees have died in Maine since the disease took hold here in the early 1930s. It got to North America in the 1890s when a beech scale insect disembarked, so to speak, in Halifax from Europe.

For a while it was thought that the scale bug was the killer. It bores holes in the bark and leaves a white, woolly-looking wax. Eventually the holes start oozing a “slime flux” and start looking like nasty black sores in the otherwise smooth bark — the dig marks in my beech tree.

It turned out the slime flux is produced by a fungus of the Nectria genus. The feeding scale bugs can weaken the tree, but the Nectria fungus does the real damage by killing the inner bark tissue. The dead areas can extend into the inner sapwood, and other fungi and beetles follow on, making a bad situation worse. Eventually the tree succumbs, sometimes quickly, sometimes after years of the illness, sometimes growing weak and snapping in wind that doesn’t bother healthy beeches at all.

Beech-bark disease has been coming and going in waves for about 80 years in Maine. The last significant onslaught occurred from about 2000 to 2004, when up to 50 percent of the beech trees in some stands died. It’s thought that drought conditions from 1999 to 2002 and mild winters that failed to kill many scale bugs, which can’t survive arctic cold, prompted the spike in deaths.

Overall the disease seems to have a mortality rate of around 1 to 2 percent of beech trees annually. This doesn’t sound like much, but Andrew Barton, in his multidimensionally revealing book “The Changing Nature of the Maine Woods,” says studies indicate beeches made up more than 12 percent of the total forest before Europeans arrived in the 1500s, while in 2003 beeches made up about 4.8 percent, and beech-bark disease shares blame for the decline.

My old beech tree has the black sores. I haven’t seen a scale bug yet; but when I do, I’ll have a word with it, and let you know how our conversation went.

Dana Wilde lives in Troy. His writings on Maine’s natural world are collected in “The Other End of the Driveway,” available from Backyard Naturalist appears the second and fourth Thursdays of the month. You can contact him at [email protected]

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