Official: Warm, wet temps dim fall glow

The abundance of rain the region experienced this summer, which is predicted to continue into October, will affect the colorful foliage associated with the changing of the seasons.

“This is the opposite of what is needed to bring out the best and timely colors, which require cool and dry conditions with the onset of fall,” said Marc Abrams, professor of forest ecology and physiology at the Pennsylvania State University’s College of Agricultural Sciences.

“I predict that there will be a late and muted leaf coloration this October,” he added.

Shorter days and less daylight also contribute to the process of leaves changing color, according to Chris Firestone, botanist with the state’s Bureau of Forestry.

“Shorter days tell the trees you don’t need to produce chlorophyll because you’re not growing anymore,” she said.

Chlorphyll is what feeds the trees and it is also what produces the green color of leaves during the growing season. When there is no chlorophyll, Firestone said, other colors appear.

“Because the chlorophyll is not there anymore, then you see the colors that were always there,” she noted. These are the reds, golds and yellows we associate with autumn in Pennsylvania.

The warmer temperatures, which are also lingering in this area, will have an affect on the foliage this year.

“Warmer days and rain keep the leaves producing a little chlorophyll,” Firestone said. “What starts the leaves getting color are crisp, cold nights.”

“I’m not expecting a total washout because even during the worst of times trees produce good to fair color,” Abrams said. “But it may take a bit more hunting to find the best color this year. What we need now, and what we are not likely to get this fall, is for cool to cold temperatures to arrive by early to mid-October to bring out the best colors.”

“We believe that clear, bright days, low, but not freezing, temperatures and dry, but not drought, conditions, promote the best fall colors,” he said.

The forecast locally calls for above average temperatures with some rain for the first week in October, not optimal conditions to produce brilliant colors.

Firestone agreed, and noted that a worst case scenario would be that the leaves could all just turn brown and die.

“We’re seeing some maples that have lost their leaves already because of rain,” she said. She attributed that to a fungal disease caused by the moist weather conditions.

In Pennsylvania, the first trees to display their colors are maples and ashes, which tend to produce the red colored leaves, followed by the oaks, which usually are golden or yellow.

Firestone noted that at some of the higher elevations, such as Bloss Mountain in Tioga County and Denton Hill, in Potter County, the leaves are beginning to change color.

In addition, some plants have thrived because of the rain and their colors are on display along state highways.

“We’re seeing color in some of the shrubs,” Firestone said, referring to the goldenrod and purple asters throughout the area.

“One thing that I have been impressed with in my 30-plus years of gauging foliage is the resiliency of the display,” Ambrosia said. “Year after year, despite the conditions, there are places where the trees show good color, but perhaps not great color, every year.”


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