I can’t help but notice…
As I drive around the city my attention is often too focused on horticultural things. In particular, I tend to dwell on things done wrong, like mulch volcanoes, or hostas planted in rock beds along a southern exposure. I can’t help it because I’m a “glass-half-full” kinda guy.
Something that’s escaped commentary by everyone, including the radio shows, is how woody vines are destroying our landscapes and woodland edges. The pictures below show a few examples.
The photo on the left is a large hedge of bayberry, planted as an effective screen. The fall coloration of the vines illustrates how significant the vines have become. The picture on the right is a Norway Spruce, with a distorted and flattened top caused by excessive shading on the apex of the tree. Adding insult to injury, there are honeysuckle shrubs growing on the bottom half of this evergreen. The honeysuckle shrubs aren’t vines, but it’s impossible to ignore them in this discussion, because they are a dominant and aggressive weedy shrub. Evergreens, especially the pines and spruces, have a hard enough time thriving here in St. Louis, and the competition from vines and honeysuckles can accelerate their decline.
No Shortage of Invaders
I can’t guarantee that I’m 100% accurate in my species identification in this blog, but I can guarantee the genus is accurate! It’s been a long time since I’ve studied botany and attempted to identify closely-related plants. I was shocked to learn how many different species of the wild grape vines there are in Missouri…six! I’m just call them Vitis species. I was surprised to learn that there Virginia creeper has a kissin’ cousin, but it’s not all that common. Did you ever kiss a cousin?
Let’s have a closer look at the spruce tree in the photo above (right panel).
The photo on the left shows numerous bush honeysuckle (Lonicera maackii) sprouts at the base of the evergreen. We all know how invasive bush honeysuckle is, and it will only take 2 to 3 seasons before the foliage from the honeysuckle shades out and kills the lower branches on the spruce. The right panel shows how the woody vines have grown as high as the apex of the spruce, topping it and possibly even killing it. Death doesn’t come by parasitism, rather just flat out competition for sunlight, water and nutrients.
Blame them birds!
So how’d these vines get there to start with? Simple answer–birds! More accurately, bird poop. The problem vines all produce fleshy berries, which are savored by birds. The seeds that get crapped germinate and it’s off to the races! While some vines can tolerate heavy shade at the base of the tree (e.g., wintercreeper, Virginia creeper, bush honeysuckle), most of the vigorous smothering vines are sun-loving. They have a very fast growth rate and can quickly extend 5 to 6 feet to reach full sun. Once the vine breaks into full sun, it spreads like wildfire.
We all know that birds love to eat berries. Below left are some poison ivy (Toxicodendron radicans) berries. Below right, some wintercreeper (Euonymus fortunei) berries.
Bird species that overwinter here in St. Louis love to roost in evergreens because of the protection from the elements. Birds always poop where they perch, and in doing so, disseminate seeds. Most, but not all, of the most troublesome woody vines have edible berries.
Look Out! It’s Gonna Fall!
When the vines become extremely well established, they add considerable mass and surface area victim tree, which can easily overwhelm the root system. That’s a problem when thunderstorms roll through with strong winds, or when freezing rain accumulates on the leaves and branches. Because wintercreeper is an evergreen, even a light coating of freezing rain can increase the weight on the tree by thousands of pounds because of the tremendous increase in surface area created by the leaves. Check out the tree on the left, suffering from wintercreeper. Is it my imagination that the black locust with wintercreeper is already leaning? The photo on the right shows a hefty poison ivy vine.
More on Bush Honeysuckle
Let’s face it, the bell curve for horticultural proficiency is skewed way to the left–meaning most homeowners are oblivious to the issues discussed herein. I’m not calling them stupid, but they are technically ignorant. For example, what’s the species of interest or value in the photo below?
It’s hard to discern but most of the trunks and branches are honeysuckle. The tree is some sort of flowering peach or cherry. It’s ugly as sheet.
Here’s yet another example of why bush honeysuckle is so invasive. There are literally hundreds of seedlings in just a few square feet under this white pine.
Other Common Vines and More Closeups
In addition to the vines already discussed, the following vines are troublesome here in St. Louis. I failed to get photos of any of the wild grape leaves, but they’re very recognizable.
Japanese Honeysuckle (Lonicera japonica)
Five different honeysuckle vines have been identified in Missouri, according to Don Kurz (Shrubs and Woody Vines of Missouri, 1997. Missouri Department of Conservation).
Virginia Creeper (Parthenocissus quiquefolia)
This woody vine is probably the most shade tolerant of all, even more so than wintercreeper. It’s a slow grower, though. A near relative is woodbine (P. vitacea), but Kurz reports that it’s not all that geographically common.
Bristly Greenbrier (Smilax hispida)
I HATE this weed! You’ve to to have the hands of Iron Man to pull this sucker out because those spines penetrate every glove made for mortals. Check out those spines! It’s got three near relatives, which tend to be located to the south of St. Louis. Thank goodness it’s slow growing!
Wintercreeper (Euonymous fortunei)
Poison Ivy (Toxicodendron radicans)
Wild Grape (Vitis spp.)
Here in St. Louis I consider the wild grape family to be the most destructive of the woody vines. They can achieve massive size and the vines themselves can easily reach 4 to 6 inches in diameter. The photo below left is typical of a wild grape takeover. The photo on the right shows the characteristic woody vines.
Honeyvine Milkweed (Cynanchum laeve)
Not all problem vines are woody, with one of the worst being honeyvine milkweed, a herbaceous vine (meaning the top dies over the winter). The photo below shows a juniper tree completed overrun by honeyvine milkweed. Click on this link to see what the leaves and seed pods look like (honeyvine).
This vine is rather unique because it doesn’t really attach itself in any manner to the foliage of the tree that it smothers, thus it can literally be pulled off the victim! The other vines have tendrils and aerial roots that anchor the vines securely.
The King Kong of all vines would be Kudzu and I’m glad I don’t have to write about this one, because it’s too rare in St. Louis.
Wisteria species escaped cultivation. There’s the Sweet Wisteria (Wisteria sinensis) and the Chinese Wisteria (Wisteria floribunda). There’s a native Wisteria in the boot heel (Wisteria frutescens). Wisteria is by far the most beautiful of the vines because of the fragrant, foot long purple flowers. Most wisteria was planted by gardeners and the vines just kept growing!
Trumpet creeper (Campsis radicans) can be a problem, but it’s a slow grower. It has beautiful red orange and yellow flowers. Hummingbirds love this plant, which is frequently planted on a trellis. I’ve never seen these growing on trees, but have seen them on fences.
American bittersweet (Celastrus scandens) is the last vine I’ll mention. It’s not as common as the vines I’ve featured in photos, and it has some decent ornamental value. Nice yellow flowers in spring are followed by hanging clusters of fruit pods that open to reveal bright red berries. The fruits can persist all winter long.
So What Should I Do About Vines?
I don’t have to deal with these bastard weeds in my garden, which is damn near perfect (yah, I’m braggin’). But my daughter and son-in-law have a Norway spruce that had three of the aforementioned vines plus bush honeysuckle growing within it’s canopy. My first order of business was to prepare a solution of 5% glyphosate and spray the foliage that I could without getting the spray on the green needles and stems. SIDEBAR [I’m not gonna debate with you over the safety of glyphosate. I worked with it for over 40 years, and I don’t plan to stop!] Four weeks later I used my hand shears, loppers and sawzall, carefully crawled into canopy, and cut the offenders off at their base.
Many of the smaller seedlings that you cut off at ground level will die, if there is still ample shade cast by the desired tree. If there’s sufficient sunlight, they’ll grow back. Thick vines have a huge root system and thus will re-sprout. This necessitates the use of glyphosate as a “cut stump” treatment. After cutting vines and bush honeysuckle off at their base, use a paintbrush to apply a 25% strong solution of glyphosate (1 part glyphosate to 3 parts water). Paint the base of the vine within 15 minutes of cutting for best results.
There aren’t any decent chemical substitutes for glyphosate for cut stump treatments underneath desirable specimen trees, for several reasons. First, glyphosate is rapidly adsorbed by the soil and rendered unavailable. This means roots from the good tree won’t be harmed. Second, glyphosate is not “exuded” by the root system of the vines you’re trying to kill. ALL of the alternative herbicides that can be used for cut stump, such as dicamba, 2,4-D, Tordon, Garlon and Arsenal, are exuded out of the root tips of the treated plant. This increases the chance of causing harm to desired trees because their roots will absorb the herbicide and translocate it.
If you choose not to use any herbicides, that’s fine, too. Just make sure you cut all all the sprouts every 3 to 4 weeks. As long as you’re vigilant you can deplete the root reserves. It may take 2 years, though.
Send your comments and questions!