Picture newly laid black asphalt bulging up here and there, then green plants pushing on through and out to the light, ready to sprout up to six or eight feet high. Who needs invaders from outer space when we have Japanese knotweed to try to eliminate? Whack and dig year after year and it just keeps coming back.
On Aug. 5 about 65 Japanese knotweed fighters met in North Creek to learn how to combat this invasive nuisance, better known as “Mexican bamboo” in the Adirondacks. I needed inspiration as a North Creek “coordinator” and I got it. Knotweed can send its rhizomes (a type of root/stem that can sprout new plants all along it) under two lane concrete roads and emerge ready to go on the other side. In England people who “plant or otherwise cause Japanese knotweed to grow in the wild” can be subject to fin es of $15,000 pounds or six months in jail! It is a terrible problem for home owners because it can destroy a foundation.
Drive in Vermont and on to even Nova Scotia as I did recently and you will see Fallopia japonica (formerly Polygonum cuspidata) lining the streams and rivers in untold numbers of acres. It is impossible for fishermen and other recreationists to get through the jungle to the water. Do we want that in the Adirondacks? We still have a chance to fight it back using the right techniques. Cutting it down once a year is worse than useless so don’t bother doing that. Mowing it by road crews just spreads it down the road because tiny pieces of the plant can sprout and grow. With weekly mowing for many months you probably can beat it, but you need a place accessible enough to mow completely.
However, when each stem is injected with the right herbicide at the right time, in the late summer and fall before frost, the herbicide is sent down into the rhizomes along with the nutrients the plant is storing for the next spring and 95% of the plants will die. Usually a few sprouts will come up the next year or two and have to be sprayed individually at the same time of year, if the stems are less than finger size and too small to inject. Landowners can do this on their own property with the right equipment and herbicide but we have a professional in the area now who can treat knotweed through a supported program run by the Town of Inlet. Donations are needed and expected if your treatment is successful to be able to continue the effort. Google noknotweed.org for more information or you can call me if necessary at 251-3772.
There are many areas of Japanese knotweed even in the Adirondacks that are so huge that only a natural enemy would be able to control it, and scientists are studying a certain insect to see if it eats only this species of knotweed, a member of the Buckwheat family. Of course Japanese beetles like it, but no one wants more of those!
But another knotweed has me pretty excited because it is a very rare one that I found just below a new beaver dam. It’s called Carey’s knotweed and the NY expert on the family has never seen a live specimen. To get there I canoed across a lake, carried a short way, then canoed across a pond in search of a different rare plant. Somehow I dredged up out of my failing memory that the botanist was looking for a knotweed with a hairy stem. So that was two rare plants, plus some beautiful paddling on a spectacular day, a good day of hunting.
An ongoing hunt: A friend who lives near Garnet Lake found a five inch swallowtail on a coneflower, one so heavy that the flower tipped down and made it difficult for the butterly to get at the nectar in the middle. It turned out to be the Giant Swallowtail, black and yellow with the tails totally yellow. Some were seen last year in the Adirondacks but most of us have never seen one. As the caterpillars eat only prickly ash in the north, a plant we have never seen either, these must just be butterflies heading out and about after emerging from their chrysalises elsewhere. As prickly ash is in the citrus family, the caterpillars are considered pests in Florida. But even with the fast rate of warming we are having, especially in winter, it will be a while until these beautiful insects will be a problem!