In June of last year, a large branch broke off one of the Bradford pear trees in the library parking lot. It damaged a fence, but it didn’t harm anyone or any vehicles. This was the second large branch that broke off the same tree, the first time a few years ago. I spoke to the leadership and asked them to persuade the city maintenance crews to trim the trees way back, especially the heavy, easily cracking branches, before they snap and smoosh a human or someone’s car. They’ve yet to do anything. The only good that has come of those trees is that a neighbor down the street from the library snuck by, just after the branches were cut and made beautiful wooden bowls from the remaining detritus. We have them on display.
I used to have mixed feelings about the Bradford pear tree. They’re pretty ubiquitous and never more obvious than around this time of year when their snow-white blossoms explode, almost always the first flowering tree to do so. They aren’t bad to look at and provide a nice beginning to the season. A few days later, the world is full of white parade confetti as the petals are pulled off the trees by March winds or spring storms, making it look like a snowstorm. Eventually, the blossoms discolor and fill the gutters with dark brown dots that eventually wash away or disintegrate. During this part of the tree’s seasonal flowering, the air is filled with the sharp ammoniac smell of a dirty catbox.
We have only one Bradford on our property. The other pear tree is a Cleveland. I got both from an Arbor Day mailing pouch and put them in the ground in our North Yard before I really knew what they were. They have grown fast, but I’ve worked to keep them pruned close, which they seem to love, but which makes them less likely to get huge and then drop heavy limbs all over my metal fence.
Now, you may be fond of these pear trees. They have pretty green leaves that pop out fast in spring and add to the sense that summer is coming. They also shed their leaves late in the year, after turning a burning purple. Despite these observable traits, there are underlying evils that most people aren’t aware of. Bradfords and Clevelands are highly invasive species. But what does that mean?
An invasive species, once brought into an ecosystem, takes over and displaces other native species by outperforming and outcompeting them. They do this by operating faster than the established order. For instance, my two pear trees produce fruit beloved by local birds. The birds eat the fruit and spread the seeds, which land in fertile soil and grow into more trees. Because the trees aren’t fussy about the kind of soil they grow in, they can rapidly take over anywhere there is space. Cross-pollination between trees creates more trees that grow faster than native trees can, so even ground that might be suitable for a maple or oak will soon enough be taken over by a pear tree. Despite this rapid growth and spread, though, pear trees have incredibly dense yet soft wood. They split easily, and they lose branches, just like the ones at the library. This is one reason why, most years, I heavily prune them.
Pears are so nefarious that some states, including my former home state, PA, have banned them. At one time, they were used as a pretty landscaping feature. Now, people understand just how dangerous they can be and how much they disrupt the other plants nearby. Had I known when I planted ours, I wouldn’t have taken up a spade to let them live and grow. It won’t be too long, and I may have to consider taking ours down. Both because of the weather and frenetic weekend schedules, I didn’t get ours pruned this year, so I will have to be extra careful to make sure that I don’t miss again to keep them growing in the trunk and not in the branches.
Most of the time, I operate under the comfortable illusion that trees are trees. The more the merrier. Trees, generally, add oxygen to the atmosphere, act as carbon sinks, and provide needed places for birds and other fauna to live. They’re also quite pretty throughout the year. The problems arise when some trees upset the order of things and hurt the trees that are more beneficial to us.
Such things are deeply complex, but it is worth considering some of the ways that an invasive tree can turn the natural order on its head. Generally speaking, there are about 1,500 species of non-native trees or plants in the US. Many of them love the warm, moist air of the South. Some came here by accident or were planted without understanding the dangers (one might cite kudzu here), while others were carried here by fauna and dropped into the soil where they quickly replicated.
By my best guess, we have fifty in our yard. There is the Chinese yam vine, which grows edible tubers, but loves to grow on other native trees. Chinese clematis, which has gorgeous upside-down cones of purple flowers that bees and other pollinators love, but that coat native trees with vines that root into the bark and also kill the canopy. The vines will also trundle through the grass and eventually get caught in your mower blades. I speak from experience. There are at least two kinds of privet. One has large, glossy evergreen leaves, and the other is called olive privet. Olive privet branches are strong and hard to break, and make really good walking sticks, but also like to grow in and around the roots of native trees.
English ivy, which sounds about as friendly as you can get, is highly invasive. Spread by birds that eat the berries, it can kill trees by covering the bark and destroying the cambium, outcompeting them for carbon and sunlight. It also digs into the crevices in your house’s brick facade, turning the pointing to powder and, if left untouched, lethal to the soundness of your home. I work all year, every year, just trying to keep this to the natural areas. It is so hard to eradicate that most years I weep with exhaustion, just to have kept it from choking the trees we want to keep.
Then there is the grass. Grass is not native anywhere except in the plains states, but some natural wild grasses can and do grow. They have almost all been outcompeted by other forms of invasive grass that, although pretty to look at, are devastating for the local ecosystems. Johnsongrass, one of the most common, is devastatingly hard to get rid of. Our former neighbor planted grass just next door, and it has slowly been taking over for the whole time we’ve lived here. It’s funny to think that I spend so much time just working to keep invasive species from destroying our property, but all around our neighborhood, county, and state are examples of battles that have been lost, especially in non-residential sectors, where invasive plants can grow without intervention.
In PA, my brother and his neighbors are being encouraged to stomp and kill the spotted lanternfly, an invasive species that is lethal to trees and other agricultural pursuits. Penn State University suggested that the spotted lanternfly, which was accidentally introduced from China, is responsible for $99 million in agricultural damages since 2019. And because the eggs can last for years, and be just about anywhere, my home county has had to put out some very strict rules to prevent more introduction and damage to PA’s beautiful forests and fields. The “stomp them when you see them” ad campaigns are a little jarring, too.
For me, the one really annoying invasive species around home is the stink bug. Also originally from PA (where it was introduced from China) it has made its way down the eastern seaboard and is now to be found in your home and mine, always somehow looking to get out and if you try to help it, it will fill the area with a sour sulfur blast that will make your eyes water and the dog look at you accusingly. There’s nothing to do about either bug in terms of eradication using insecticides or other mass destruction means, mainly because those options would also nuke native species.
I don’t suppose we could figure out a way to engineer the lanternfly or the stink bug to attack only dangerous pear trees. I could easily cut down ours, once they are ransacked, and plant pretty pink dogwoods in their place. Of the five dogwoods we had when we moved here fifteen years ago, there are only two left. The attackers aren’t invasive, but no less dangerous. Anthracnose, a fungus that infiltrates wounded or badly pruned trees, takes only a couple of years to fully destroy a tree. The dogwood borer, a moth that also attacks the tree and bores into and under the bark, can easily kill a dogwood in just a few years. Assuming that all dogwoods are extremely susceptible, it looks like our trees and all dogwoods will be going the way of the American chestnut, black and white ash tree, and the Eastern Hemlock. That’s not good for anybody.
So, yes, I happen to be a hypocrite, having a distaste for invasive pears, while having planted two variants on my property. Live and learn. I just hope that whatever damage I may have inadvertently done to my property as a result can be fixed by planting other trees in other places and encouraging native species to have as much room to grow as possible. The battle may be essentially unseen, but it is one that does matter.
So the next time you’re walking around your neighborhood and are tempted to gasp at the pretty white blossoms in yours or your neighbor’s yard, remember that what you’re actually seeing is something that is slowly shifting the local ecosystem away from health and stability and rapidly toward a dangerous precedent that may be helping to kill other native trees. And if you happen to be passing my trees, will you turn a blind eye, for now, please?
