Pears on the Loose!
For many people, the flowering of pear trees in our front yards and along the highways signals the beginning of Spring. In years past, these trees (known as the Callery pear, Pyrus calleryana) burst into bloom in the first few weeks of March. This display is shortly followed by the buzzing of bees and other insects dancing from flower to flower, and tree to tree. These insects are attracted by the perfume of flowers – which unfortunately to our noses resembles a rank stench radiating from the odoriferous blooms.
But this year has been quite unusual, with its inconsistent temperatures and spring storms. Many of us have seen delayed flowering or just browning of buds, or early leaf-out of pear trees in many areas. How will this impact seed production in this lovely but invasive plant species? Will it serve to curtail fruit production? Is this the beginning of the end for this ornamental tree that was once the darling of the landscaping world, being sold in nurseries throughout the United States? The answer is more likely “No”, due to the tenacity and hardiness of this tree originally imported from China in the early 1900’s.
In the United States, this tree is usually more well known by its cultivar names: ‘Bradford’, ‘Cleveland Select’, ‘Aristocrat’, ‘Capital’, ‘Autumn Blaze’, among others. ‘Chanticleer’ was even named 2005 Urban Street Tree of the Year by the Society of Municipal Arborists. Just as its popularity skyrocketed in the early 2000’s, these trees began to naturally appear and spread along roadsides and forest edges. Triggered by cross-pollination among these different cultivars and even with its own rootstock, infestations of the Callery pear have now become a source of consternation to managers of parks and natural areas. The trees can form dense populations in natural and disturbed sites, and more recently, can even be found growing in the middle of forests! Wild trees are extremely difficult to remove, often rebounding as shrubby thickets if just cut at the base and left alone.
Within the last few years, the Callery pear has started to show up on lists of invasive species in the United States. However, because this plant is still sold in some places as an ornamental tree and consequently is of economically importance, regulation of the Callery pear is exceedingly difficult. Ohio is the first state to outright regulate the Callery pear, banning it from commercial sale and distribution in January 2023 (following a 5-year phase out period). South Carolina will be the second such state, with a 2024 regulation date. In Pennsylvania, the Callery pear was added to their noxious weed list in Nov. 2021, meaning that it cannot be distributed, cultivated, or grown within the state. More states are now considering how to deal with the Callery pear, and if so, whether regulation of commercial sale is even feasible.
So the fate of the Callery pear – at least as a prominent landscaping tree – seems to be on the decline. Unfortunately, the “cat is already out of the bag”. But what can be done now that the Callery pear is spreading throughout the Midwest? Continued vigilance is necessary to keep the tree from spreading northward with our warming climate. People should not be planting this tree in their yards, especially if they live near natural areas. So, anything we can do now to restrict the spread of this ornamental tree will only help reduce the problem our society has inadvertently brought upon ourselves.
This article has been contributed by Theresa Culley, PhD.
Theresa is a Professor and Head of the Department of Biological Sciences at the University of Cincinnati, Ohio Invasive Plant Council Committee Chair (Plant List Revisions), Co-Director of the Public Gardens as Sentinels against Invasive Plants initiative, and Midwest Invasive Plant Network Board Member.
