Bradford pear tree poses an ecological threat in Ohio

Bradford pear tree poses an ecological threat in Ohio

Early to mid-April is one of the most beautiful times of year in Holmes County because that is when the first of the trees and flowers start to bloom. Among them is the Bradford pear tree, a small ornamental that has long been regarded as a beautiful addition to a springtime landscape.

You’ll find these trees dotting tree lawns, housing developments, commercial landscapes, and woods and unkempt fields, where this invasive species tends to spread like wildfire, choking native plants and strangling young forests as it grows.

Gary Graham, Ph.D., natural resources specialist of the Ohio State University Extension in Holmes County, does not mince words when it comes to the Bradford pear. “Have you heard of kudzu? This is the new kudzu. It is very invasive, and there is a great effort to try to get it out of the landscape.”

For such a pretty flowering tree, the Bradford pear poses a huge ecological threat to the Ohio landscape. Graham said this tree, which is a cultivar of the Asian Callery pear, is likely among the top-five worst invasive plants in the state. Why? Because these trees are pushy, able to easily spread out of well-maintained tree lawns and landscapes and into the surrounding woods and fields.

These are trees that can grow in almost any soil type and they grow fast. They’re capable of outcompeting Ohio’s native trees and plants, particularly in thinned forests and open fields, which results in a drastic reduction of biodiversity.

Worse, these trees are not sterile. They will not pollinate other Bradford pears, but they will cross pollinate with native Ohio pears and other types of trees. The problem with this is in the Callery pear’s genetics.

“What has happened,” Graham said, “is that the characteristics of the Callery pear are so dominant that when the seedlings come up, they revert back to the parent tree, the Callery pear, which has four-inch-long thorns that will puncture a tractor tire if you run over them.”

In other words, once this invasive species takes over, you’ll have to go to extreme measures to eradicate it. A tractor with a brush hog just isn’t going to cut it.

Graham said that fortunately the Callery and Bradford pears are easy to control, but you’ll need to use a bulldozer or something without rubber tires to clear heavily infested land.

“You can cut the tree off at the base, and there are a couple of chemicals that will work really well,” he said. “If you don’t spray the base, it will come back, shooting up little suckers all over the place.”

As if the rampant spread of these trees combined with the extra steps needed to eradicate them wasn’t enough, the Bradford pear comes with a few fatal flaws that make it unsuitable for landscaping, despite its pretty flowers.

“It’s just a nasty tree,” Graham said. “It’s so beautiful this time of year, and in the fall the leaves are a bright red. But they put off a horrible stench, the flowers and the rotting fruit. And they don’t have a long lifespan. The way their genetics are, the trees have a very steep V-shaped crotch, and those will snap off. Fifteen to 20, maybe 25 years, is the lifespan.”

And that’s the rub. The Bradford pear doesn’t get a lot of attention, at least not until it blooms. This leaves homeowners everywhere in the dark. They’re lured in by the pretty flowers and decide to plant one of their own, unaware that they are signing themselves up to deal with a smelly tree that only looks nice for a few weeks each year, one that is liable to split in half and require expensive removal in just a few short years.

So how did this problematic tree get to be so widespread? It started in the early 1900s with an effort to save native pear trees afflicted with fire blight by grafting them to the root stock of the Callery pear. This tree started attracting attention for its profusion of blooms, and by 1964 a cultivar of the Callery pear, the Bradford, was released to the public as an ornamental tree.

Researchers quickly realized the Bradford came with far more problems than first imagined, but it was too late. “They tried taking the Bradford and crossing it to create newer cultivars that didn’t have these issues, but it didn’t work,” Graham said. “All of these cultivars of the Bradford, they revert back to the Callery again.”

These days there are two factors that aid the spread of the invasive Bradford pear. For the most part nurseries have stopped selling them, and municipalities are refusing to plant them, but the general public is largely unaware of the problems associated with these trees. Because of this, there are still a few retailers out there who will sell these trees to unsuspecting shoppers.

“Respectable nurseries got rid of them years ago, but there is still a demand for them, and that is part of the problem,” Graham said.

The larger reason for the spread of these trees is the fruit. “The key,” Graham said, “the reason why these invasives do so well is because they produce a lot of fruit, and that is attractive to birds. But the fruit is very low in nutrients, so they have to eat a lot of it.”

When birds are eating more fruit than they normally would to make up for the lack of nutrition, that means they also are spreading more seeds than they normally would too. Thus the Bradford pear spreads, breeds with other trees and produces seedlings that genetically revert back to the thorny Callery.

Clearing your property of Bradford and Callery pears is no easy feat, but with the right tactics it can be done. Graham recommends people get in touch with the Holmes County Extension Office for details about removal methods and chemical treatments.

As for alternatives, Graham encourages people to plant native hardwood trees. “They’ll look awesome, but they’re just slower growing. There’s nothing wrong with planting a good, old sugar maple tree, a red oak or a white oak.”

Just make sure you plant hardwoods in the right spots so that they don’t interfere with power lines or other utilities. If you really want a flowering tree or shrub, try serviceberry, hawthorn or even the native sweet crabapple. Graham cautions people to choose a newer crabapple variety as they are more tolerant of anthracnose, a disease that causes leaves to drop.

There are lots of great choices for ornamental trees, just steer clear of the Bradford pear.

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