National Invasive Species Awareness Week is this February 24-28. How can we go beyond awareness and start getting rid of invasive species? I’d suggest we start with the English ivy growing on trees. Bang for the buck, it’s the easiest invasive plant to remove. It’s not physically demanding – you just have to pay close attention.
There are two main benefits to removing English ivy from trees. First, the vines are hazardous. English ivy vines make trees top-heavy and likely to break; see the picture above of an ivy-covered tree that snapped off in an ice storm. The vines also trap moisture close to the bark, causing the bark to rot. Second, removing vines slows the ivy’s spread, because English ivy only flowers and makes seeds (see the picture at left) when it’s growing vertically.
The procedure really is simple. Make two cuts to each and every vine growing up the tree: first, 1 or 2 feet up the tree, and second, close to the base of the tree. (See picture at left.) The reason for making two cuts is to ensure that the cut ends of the vine can’t reunite and continue growing. Use clippers or a saw as needed. Be careful not to damage the bark. Then, throw away the cut-out sections. That’s it!
The only tricky part is to make absolutely sure that you’ve cut all the vines. Ivy can hide in the furrows of the bark. If a vine is so deep in a furrow that you can’t cut it, don’t damage the bark to get to it. Instead, follow the vine down to the base of the tree and cut it there. And if a vine is too large to sever, slice into it with a saw or hatchet and paint the cut with concentrated herbicide as described below.
It’s not necessary, or desirable, to pull down the vines growing up the tree. Ripping off the vines can damage the bark and might pull down branches. This is bad for the tree, and for people on the ground! The vines will dry out and turn brown in a few weeks and will blend in with the bark. In a year or two they’ll fall down on their own. This all takes a while because English ivy leaves have a waxy coating that holds water inside. So it will be slow. But you can be sure that ivy needs to be connected to the ground to live. In other words, it’s not an epiphyte like most orchids. If it seems like the ivy is taking an unreasonably long time to dry out, check again to make sure you’ve cut all the vines.
A couple of safety items: the sap of English ivy can cause a rash like poison ivy. Wear long pants, a long sleeve shirt, rubber or nitrile gloves, and eye protection. English ivy sap can cause a rash even if you’re “immune” to poison ivy. And speaking of poison ivy, be on the lookout – leaves of three, let it be – because it can hide amongst English ivy vines. Note that poison ivy is native to Virginia, so it’s up to you whether to remove any that you might find.
The ivy will grow back, of course. To help keep it off the tree, pull the vines out of the ground for a few feet around the base of the tree and cut again to make an ivy-free zone. The roots of English ivy are fairly shallow, so this won’t be difficult. If the ground is moist, it’ll be even easier.
If you’re really ambitious, you can then remove the ivy from a larger area. I described one method in a Garden Shed article a few years ago. The basic idea is to use a shovel to cut the vines into strips (see picture). Then, cut across the strip at ground level using hand clippers and pull the ivy back towards you. Work backwards until the whole strip is cut free. It’s slow going, but it’s a very thorough method.
Judicious herbicide use can help remove ivy from the ground. This might be needed for very thick vines that can’t easily be pulled up. Immediately after cutting a vine, dab a little concentrated glyphosate or 2,4-D on the cut end that’s still embedded in the ground (see picture). Use a cotton swab or an applicator bottle, i.e. a plastic bottle with a sponge over the opening. It’s important to do this right after cutting the vine, or the stump will seal and won’t take up the herbicide. This method uses little herbicide and has little chance of affecting anything other than the ivy you’re trying to kill. When using herbicides, always follow the instructions on the label, and use personal protective gear like nitrile or rubber gloves, long sleeves and pants, and eye protection.
There are many invasive plants growing in Virginia, but English ivy is probably the most common, and it’s easy to remove. For information about other invasive plants, Blue Ridge Partnership for Invasive Species Management (PRISM) are the folks to consult about identifying and removing invasive plants in our area. Check out their fact sheets on invasive plant species, or sign up for their newsletter, which includes information about the best times to act against particular plants. Finally, be on the lookout for National Invasive Species Awareness Week events in your area – or start some up yourself!
References and further reading
English Ivy and Winter Creeper (PDF) Blue Ridge PRISM
Take Ivy off Trees Tree Stewards of Arlington and Alexandria
All pictures by the author. CC BY-NC-SA 4.0