Hi friend,

Did you know that one of the most invasive trees in the eastern half of the United States was introduced on purpose by the US government?

That’s right, the smelly Callery pear and its man-made cultivar the ‘Bradford’ pear were both cultivated intentionally by the US Department of Agriculture.

Callery pear (Pyrus calleryana) is a tree that’s native to China and Vietnam and was first introduced to the US by the US Dept of Agriculture in 1916 to breed with the common European pear (Pyrus communis) to improve resistance to disease in the commercial pear industry.

Around 1950, the US Dept of Agriculture began introducing and recommending cultivars of the Callery pear including ‘Bradford’ as an ornamental for landscaping.

When the Bradford pear cultivar was created, it was thought to be sterile and unable to reproduce.

And while that’s technically true, it can very much crossbreed with other pears and revert back to something closer to the Callery pear straight species (oops!)

Praised for its ability to grow in low-quality soil, its disease resistance, showy spring flowers, and the (incorrect) theory that it couldn’t spread, Bradford pear trees were planted prolifically across eastern US landscapes with the encouragement of the US Dept of Agriculture from the 1960s-1990s.

And now we’re dealing with the consequences.

Since Bradford pear trees are created from grafting, they’re all genetically identical and unable to self-pollinate.

This made horticulturists think that it would not be able to spread.

However, it’s very capable of cross-pollinating with other Callery cultivars and with offshoots from Bradford root systems.

This created the spread of the “Wild” Callery pear.

Wild Callery pears have taken over huge areas across the eastern US because of their ability to grow in disturbed soils, fast growth rates, and resistance to disease.

The showy flowers of the Bradford pear also have an extremely unpleasant odor, and the tree’s branch structure and growth rate lead to weak branches that are easily damaged in even mild storms.

As rainstorm frequency and severity increase with climate change, Bradford pear trees are a huge liability. They often fall on power lines and damage homes, vehicles, etc.

The spring flowers that made these trees so appealing also bloom earlier in the season than most US native plants start growing.

This allows the Callery to shade out and outcompete native species.

The wild Callery also has these fun 4-inch long thorns that can pop tractor tires! This makes it difficult to clear out large areas of these trees with machinery.

Invasive plants have a huge negative impact on our native ecosystems.

But so do the herbicides that people use to get rid of them.

P.S. I'm currently having a sale in my online shop!

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Tory is an ecologist and landscape consultant. He helps North American gardeners transition from using outdated and harmful but status-quo techniques to using their yards to improve the health of our planet. Along with being a gardener for over 10 years, Tory has a Master of Science degree in Sustainable Design and is certified in Regenerative Soil Science.​

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