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Grafting may help eliminate a problematic tree
The adage about making lemonade when life hands you lemons may be one definition of optimism.
But what to do when life gives you pears?
The village-owned portion of Cold Spring’s urban forest, found mostly along its streets and in its parks, has close to 500 trees. They include more than 40 species, including red maple, black locust, zelkova, pin oak, weeping willow and Eastern red cedar. Ten years ago, the Cornell Cooperative Extension Program put their replacement cost at close to $2 million.
Beyond their monetary value, urban trees provide oxygen, shade, habitat, beauty and even psychological wellness: Street trees have been proven to relieve stress. People love trees, and for good reason.
The Callery pear, however, is a weak link. It accounts for 12 percent of the Cold Spring inventory, including 21 trees along Main Street. Known alternatively as Bradford, Aristocrat and Cleveland Select, Pyrus calleryana has white springtime blooms and a deep purple and red fall foliage. It grows fast, thrives in a variety of soil and is resistant to serious disease.
Native to China and Vietnam, the Callery pear was brought to the U.S. in the early 1900s by the fruit industry as part of an attempt to develop a fire- and blight-resistant tree. It was planted in many Hudson Valley communities.
Over the years, its good traits have been eclipsed by its bad, including weak structure (two of the Main Street trees have split or toppled); susceptibility to storms (six have been removed because of damage); an annual crop of sticky fruit that falls onto parked cars; and, most recently, the spread of invasive, thorny hybrids that have taken over the northern end of the former Marathon Battery property on Kemble Avenue and are expected to advance toward Foundry Dock Park and Foundry Marsh.
Members of Cold Spring’s Tree Advisory Board hope to improve the village-owned tree stock with grafting, which, over time, could essentially convert Callery pears into a more desirable species.
Grafting removes a shoot or “scion” from one species and implants it in another. The scions eventually begin to take over. For the graft to be successful, the tree species must be closely related.
“In April, six Callery pears were grafted with one shoot each from Hawthorn, shadbush, quince or fruiting pear,” said Charles Day, who heads up the experiment. “The trunk will remain a Callery pear, but the shoots from the grafts will eventually become branches.”
That transition could take as long as four years, he said, adding: “Until then, they could look a little strange!”
Day said grafting is commonly used in commercial orchards to change varieties, usually within the same type of fruit. Compatibility is a “tricky thing”; a graft can grow for a year and suddenly die. Day plans to assess the first grafts this winter and hopes to add more to the most promising trees.
Day said residents who have Callery pears should probably just have them removed. “Mature Callery pears need careful pruning to keep them safe, because their branches tend to break off, and the trees at any age are potentially invasive,” he said.