When good plants go bad

Updated Nov 27, 2015
  • By Pamela Corle-Bennett
  • Contributing Writer

In the horticulture world, sometimes good plants go bad. No matter how great a plant may start out to be, there are circumstances that we just can’t predict that cause nature to get out of line.

Take the story of the callery pear (Pyrus calleryana). Most people know this tree by the name of ‘Bradford’ pear.

‘Bradford’ is actually a cultivar of the callery pear that was discovered to have the characteristics of a good street tree along with beautiful white flowers, wonderful maroon fall color and most importantly, no (or very few) fruits that would make a mess on the sidewalks.

This tree was widely planted as a street tree and in all new commercial and housing developments.

Unfortunately it was quickly discovered that this particular cultivar had very poor crotch angles (where the branches come out from the trunk).

This led to a lot of broken branches due to heavy wind and ice. In many cases, an entire side of the tree would split off.

Breeders went back to work and developed other cultivars that had better branching angles. The strongest angle for a branch is between 45 and 90 degrees.

New cultivars came to market with different fall colors and much better branching habits. They included ‘Washington’, ‘Aristocrat’, ‘Cleveland Select’ among others.

The ‘Bradford’ pear cultivar was a great cultivar because is really did lack fruit - in the beginning. It was considered genetically self-incompatible which meant that it couldn’t self-pollinate and produce fruit.

However, sometime around the mid-1990’s we started to see tiny hard brown fruits develop on the ‘Bradford’ pears. I had nurserymen such as Peter Scarff of Scarff’s Nursery in New Carlisle call and ask if I had recently noticed that the ‘Bradford’ pears were producing fruit. It was a very strange thing for us to see after so many years of no fruit.

A researcher at the University of Cincinnati, Teresa Culley among others discovered what was happening and why we were beginning to see fruits on these trees.

The other cultivars with the better branch structure were crossing with the ‘Bradford’ pears and fruits started to develop.

In the early 2000’s all of a sudden we started noticing that there were a lot (emphasis on LOT!) of pears starting to grow in areas where they weren’t growing before. We noticed them in fields, empty lots and especially along the highways.

I have a five-acre former farm field and in the back of the lot, where we don’t mow on a regular basis, we have noticed seedlings starting on their own.

These were not planted by humans but rather transported by birds.

The fate of these trees in native areas is still unfolding. Natural area and preserve managers are concerned that these particular trees are becoming an invasive threat.

With the decline of ash trees in natural areas, we wonder if these pears will begin filling in the gaps in the natural areas.

It’s an interesting story and one to prove the point that we never really know everything when it comes to nature! We have so much to continue to learn and study.