Ever wonder what those plants are that are taking over your backyard? or the side of the road? or the nearby hiking trail? Freya, a monthly blog correspondent and Bucktails and Ursids alumna, writes about her battles with these few invasive plant species and her battle to rid them from their improper homes.
Wherever you’ve lived, I’m sure you’ve seen invasive plants. Growing up in the south, I remember seeing kudzu along roads – masses of it would cover trees, wrapping around and strangling them, dragging them down into the depths of the seasonally writhing kudzu sea. It’s like a slow motion horror movie. There are tales of people going on vacation, and returning to a house and car swamped with vines. It’s easy to believe, since kudzu can grow up to a foot a day! Kudzu is very dramatic and obviously bad, but there are many other invasives more subtle, yet just as destructive. An understory can appear very healthy, until you learn a little plant identification, then it can look very different indeed.
What makes an invasive? Lots of foreign species are brought over, often because there is something nice about them. Many of these end up living peacefully in their new habitats. Why do some of them go bad? Well, there are a few things that the invasives tend to have in common: Most of them are really, really good at spreading themselves, be it with hundreds of seeds, yummy little berries, or hyper-aggressive roots. They all take advantage of disturbed areas like roadsides and clearcuts. Finally, they are all away from the controls they evolved with and – this is important – the local controllers, like deer, have rejected them. With nothing to hold them back, they quickly monopolize resources, and outcompete natives.
This summer, I volunteered to pull invasives in public parks with Friends Of Murrysville Parks (FOMP!), a group dedicated to this cause. They taught me about a bunch of problem plants: Where they came from, how they spread, why they are a problem and must die, and the best ways to make them die.
Garlic mustard, waving its green leaves and clusters of tiny white flowers, can actually look rather lovely. Looks are deceiving. Garlic mustard was brought over by early European settlers for medicinal and culinary purposes. (We’ve tried eating what we pull out of our yard; it’s strong-tasting and just O.K. in soups.) While it’s easy to pull each plant, a park or forest filled with the stuff is daunting. Deer don’t like it, so they’re no help. Seeds are viable in the ground for up to five years, so, even if you pull them all up, clearing an area still takes years. I’ve spent lots of time controlling garlic mustard, and hand-pulling is kinda fun and satisfying, IF you do it before the seeds start to drop. I spent an afternoon in late summer pulling ripe garlic mustard – easing each plant, with it’s open seed-pod, out of the ground, turning it carefully to spill as few seeds as possible and getting it into a trash bag. Tedious.
The damage of invasives can go beyond just squeezing out other plants; it extends to the insects and other herbivores that depend on those plants. Garlic mustard is an example: The rare West Virginia White butterfly mistakes garlic mustard for its host plant, toothwart, and any eggs it lays on garlic mustard die. This can destroy local populations.
Giant Japanese knotweed is another rogue plant. Once you recognize it, you start seeing it all over; it covers countless road margins, and I’ve watched it conquer our neighbor’s hillside. This stuff grows tall, and thick as a bamboo forest. It was brought from Japan, for erosion control, and let me tell you, our neighbor’s hill isn’t going anywhere. It often starts up in disturbed places and riparian areas, where it can actually clog upsmall waterways.
Japanese knotweed mostly spreads with rhizomes, which can break off and travel in floods to start new colonies where they land. These rhizomes are so aggressive that knotweed can grow under a road and come up on the other side! Once Japanese knotweed is established, it is really hard to get rid of; it will keep coming up from the roots for years. Once it’s removed, you have to plant some other fast-growing thing to hold the line when the knotweed tries to come roaring back. Persistent mowing can gradually kill a stand. Herbicides can work too, but you always have to be careful of the surroundings; most herbicides aren’t stream friendly.
Bittersweet is sort of the kudzu of the north. It twists around trees, smothers them and pulls them down. It does make very pretty berries; you can still see them in fall flower displays. According to the Department of Conservation and Natural Resources, bittersweet’s use in craft projects contributes to its spread. Animals also disperse the berries, and rhizomes travel underground. Again, once it’s established, it’s nigh impossible to get rid of. Mowing frequently can keep it down, but mowing occasionally promotes root sprouts. The best control comes with cutting the vine at the root and coating the stump with an herbicide.
The last species I’m going to talk about are multiflora rose and privet. These are the ones I spent most of my volunteer hours fighting with. They’re both very fast to spread and tough to stop. We’d drive into a park for a workday and everything would look verdant and healthy – until we stepped out of the car and realized that that lush understory was entirely privet and multiflora rose – our arch nemeses!
Multiflora rose was brought from Japan to the U.S. to help with erosion, livestock fencing, and even to be planted as a crash barrier along highways! Basically, it was brought because it grows in spiky, impenetrable masses. Real smart, guys. Real smart. Privet species were brought in the 1860s for landscaping. They both make berries which animals spread fast, far and wide, and they will completely take over an understory. They can both grow back from a single root or twig left on the ground, so when we cut them, we would stack all the plants on top of dead logs and as narrowly as we could, to minimize their contact with the ground. Since the tiniest root can become next year’s thicket, the best way to kill them is to cut them off at the base and put herbicide on the stump.
Pia van de Venne , the woman who organizes the FOMP, has dedicated her life to fighting invasives. She works every day, year round, except days with too much snow, with anyone who will come with her. She and her crew keep three or four parks under their wing. That’s all, and that’s what it takes. Controlling invasives, once they’ve got a foothold, takes commitment, hard effort, and the work never ends. Prevention is the key, and so educating people on this stuff is important; even now, after they have become such a problem, I still see burning bush and bush honeysuckle, two other common invasives, planted in parks. Keep in mind, even Darth Vader was once just a little babe-in-arms. Catching things early and stopping them from getting out of hand will save lots of natives and save us lots of time and trouble later. If you see an invasive, kill it for me, O.K.?