By mid-August many of us have sighed with relief and settled into a comfy chair in the shade. Planting is done. Weeds? Either under control or not going to be controlled until Jack Frost comes along. We pick our tomatoes, fill a few vases with late bloomers and generally relax. But this is a good time to work on controlling invasive plants. Let’s look at a few of the culprits and what we might do. Three shrubs or small trees I have been working on are buckthorn, multiflora rose and bush honeysuckle.
Buckthorn is difficult to eradicate because if you just cut it down, the roots send up dozens of new plants. If you are patient, you can double girdle a trunk with a small folding saw, cutting through the bark and green layer beneath it but not cutting into the core wood beneath that. This prevents the leaves from feeding the roots, starving them. I’ve done this, but generally it takes three years to kill the tree. No new shoots come from it. But I’m 80 now and don’t want to wait three years.
So what have I been doing? Digging out the plants, roots and all. It’s slow but generally doable. I shall see next spring if the inevitable fragments of roots left in the soil send up new shoots. But if they do, they should be easier to get out. I am working on plants no more than an inch and a half in diameter at the base.
I start with my CobraHead weeder, raking through the soil, exposing roots and teasing them out. I then rock the main stem to loosen up the roots some more, and I try to get roots exposed on one side and pull them out of the ground, then tip the small tree over the other way. I then get a long shovel under the center of the tree and try to pry it up. If there are deep roots going straight down, I slice them off and try to dig them out after I have removed the tree and the surface roots.
Buckthorns are showing ripe fruit in my neighborhood right now — dark shiny berries that have a pit like a small cherry in the middle. Birds eat them and excrete the seeds, starting new plants. Common buckthorn has male and female plants, and only the females have berries. Glossy buckthorn is self-pollinating, so all produce fruit. I have a male common buckthorn and although it has not made fruit it has sent up about three dozen root sprouts in a radius of 6 feet or so, all interconnected.
Most trees have either alternate or opposite branching of leaves and branches. Not the buckthorns; they have “sub-opposite” branching. Twigs are not quite opposite on the branches, one just a little below the other. That’s a good way to help identify buckthorns.
Multiflora roses (Rosa multiflora) were introduced by the USDA in the 1930s for use in erosion control and as living fences. They were used by highway departments in the 1960s in divided highways as crash barriers and a way to screen headlight glare. Unfortunately, they escaped and became a dreadful noxious invasive. They can strangle trees and make it impossible to walk through areas where they have taken over.
Birds introduced multiflora roses to my property just a few years ago. I had seen it elsewhere and knew it, so I began digging it out before it became a serious problem. But it will be on my “to do” list, I fear, till the day I die. I have found its roots spread far and wide, and the thorns are dreadful. This is a job to hire out if you can find someone willing to take it on, and must be done every year.
I try to at least cut it back before animals spread the seeds found in the rose hips. Digging it out is a “later in the fall” project for me so I can wear heavy canvas jeans, jacket and gloves. The roots, in my experience, are not particularly deep. However, that may vary according to the type of soil you have. Digging out roots is always easiest when the soil is moist, not dry.
There are many species of honeysuckle, both native and foreign invasive that grow in New England; of these, four bush honeysuckle are invasive. If you have honeysuckle and didn’t plant it, it probably is one of the invasive ones. I have honeysuckle as a problem plant at the edges of my property. Right now it is displaying juicy red berries that have three small hard seeds inside. If you cut the stem, it has a hollow center, or a dark area at the center.
In my experience digging up a honeysuckle is much easier than getting out a buckthorn or multiflora rose. This is due, in part, to the fact that the roots seem to stay closer to the surface and can be exposed by digging with my CobraHead weeder. Sometimes they break when I pull on them, and I don’t really know if those bits will create new plants. I will mark where the honeysuckles were pulled, and revisit the sites where they were growing next spring to see if new plants are growing.
The list of invasives is long but most gardens have some of them. Both New Hampshire and Vermont have good websites with complete lists. New Hampshire will identify invasives for you from photos you send in. The most important things to do are to learn about your invasives, and to work every year to remove some.
Removing invasives is hard work but very satisfying. I recommend getting rid of root systems and fruit in household trash or in your fireplace — never in your compost pile, where they may survive and thrive.
Henry’s column appears twice monthly. Reach him at henry.homeyer@comcast.net.
