KC Gardens

Ornamental pears: They’re invasive too

Flowering pear tree
Flowering pear tree

From Dennis Patton:

Last week I touched a nerve with my discussion of ornamental pears and the process of topping to preserve these trees. I rather expected this reaction as I penned the article. I knew I was pushing the boundaries. But for those that know the real Dennis Patton, you can chalk it up to being in “one of his moods.” Or, “there he goes again getting up on his soap box.” Putting all that aside, the article did start a conversation on this blog and on Facebook, and got people thinking about trees and how important they are to our world.

Ornamental pear, Pyrus calleryana, includes a number of specific cultivars or varieties of trees. The variety ‘Bradford’ is the most famous. Other varieties include ‘Aristocrat,’ ‘Autumn Blaze,’ ‘Capital,’ ‘Chanticleer,’ ‘Redspire’ and ‘Whitehouse’. As a group they are often referred to as ornamental pears, Callery pear, or are simply lumped into a single category called ‘Bradford’ pears.

‘Bradford’ was the first cultivar and unfortunately had the worst branching structure. They broke in adverse conditions. Later introduced cultivars have better branching habits and as a result do not fall apart as easily. Yes, they are still prone to problems. But they must be placed under more stress than the ‘Bradford’ in order to split.

Reading all the comments on the various social media outlets, including KC Gardens, Twitter and Facebook, I learned that followers are very passionate. I also learned that one of my points about this tree missed the mark with some. Everyone connected with the comments about pruning. But a few overlooked the comments about ornamental pears being an invasive species. Some agreed fully with my comments about invasive species, while others defended (which is their right) the beauty of the tree and its value in the landscape.

Sticking with the online theme of social media, I am borrowing this definition of invasive species from the reliable Internet source Wikipedia. An invasive species is defined as “a plant or animal that is not native to a specific location (an introduced species) and has a tendency to spread, which is believed to cause damage to the environment, human economy and/or human health.” Simply put, an invasive plant escapes from our yards and takes over the native areas, choking out the local native flora and fauna.

This is what is happening with the pears.

Ornamental pears are mostly self-sterile, which means they cannot pollinate themselves. When the only variety on the market was ‘Bradford’ we rarely saw fruit. Then, as newer genetics and varieties came on the market, these pears cross-pollinated and began to heavily set fruit. Fast forward a few years and now we have pear seedlings popping up all over the metro and beyond — mainly around roadside fences, under power lines, and in grassy fields and native areas. Thank you, birds, for pooping the seeds all over the place!

These seedlings, or as I call them, weed trees, have now been deemed an invasive species. Unfortunately, once the “cat is out of the bag” there is no going back. We are destined to have these escaped trees freely reseeding in perpetuity. So the second point I was attempting to make in last week’s article was for the complete removal of ornamental pears, versus topping. Maybe we should be removing this tree because it causes more problems in the environment as a whole, as opposed to the singular problem of them peeling like a banana in an ice storm. Bottom line, they are causing damage to our native lands and wildlife population.

My goal was to help you start thinking about the value of this tree if you have one or know someone that is concerned about their tree. Planning to keep the tree around at all costs may not be the best plan of action. All living things have a life cycle. Yes, that may seem cold and cruel. But in looking at it through a scientific lens, sometimes we just need to know when to pull the plug.