Mother Nature and Jack Frost are at odds this season. The result: Trees hanging onto their leaves.
At Cornell Cooperative Extension of Monroe County, Walt Nelson explained what’s going on with the deciduous trees — those oak, maple, elm and others that are supposed to drop their leaves in the fall.
“Many areas of New York, including the Greater Rochester area, had a different fall in 2017,” said Nelson, the extension’s horticulture program leader. “Summer-like weather extended into October, abruptly ending the growing season with freezing temperatures in early November.”
He said that typically, cooler weather and shorter day length stimulates the formation of an “abscission layer” of cells where the leaf stalk joins the twig. That layer acts like a tourniquet, causing the leaf to break from the twig. But this year, that crucial layer that sends leaves falling to the ground didn’t form — or formed badly — leaving leaves and twigs intact.
After the warm early fall and then a freeze right after Halloween, there was no gradual move into fall, Nelson added. “Everything was still growing,” he said. That was the impetus for what happened. He mentioned that while shorter days are indeed a factor in prompting leaves to fall, it is not the only driving force and colder weather is also needed.