Fall foliage shows effects of drought

UNIVERSITY PARK, Pa. – There have been other years when Marc Abrams worried that weather conditions threatened the vibrancy of Pennsylvania’s fall foliage display.

But somehow, each autumn the leaves produced breathtaking colors despite natural adversity.

But this year’s drought – the latest in a four-year span of sharply lower-than-normal precipitation – might be the mother of all foliage-foiling weather conditions seen by the professor of forest ecology and physiology in Penn State’s College of Agricultural Sciences.

Less than expected. With leaves on an alarming number of trees across the state already going from green to a crispy brown state, Abrams wonders if this might be the year that autumn colors are disappointing.

“I don’t want to sound too grim because over the years, I have been impressed at how resilient the fall colors on Pennsylvania trees are,” he said.

“A certain amount of autumn color always seems to come through no matter what. But I am concerned that this fall the persisting drought is going to have a negative impact on the foliage display.”

Different colors. Abrams sees a very real possibility of trees in regions where the drought has been most severe – in the southeastern part of the state, for example – exhibiting muted colors.

“I am concerned about the colors in some areas,” he said.

“We are seeing that trees are severely stressed in many areas. There are signs of widespread wilting of leaves, early leaf fall and browning. Once leaves wilt, they will not go through the normal coloring process.”

Ideal situation. The ideal situation, Abrams explained, would be for two weeks of wet weather to hydrate the trees going into an “October cool down,” marked by normal fall weather with sunny, warm – not hot – days and cool to cold nights make the leaves bright.

Abrams pointed out that a so-called Indian summer hot spell is not good for a bright foliage display.

“Every year is different with the foliage,” Abrams said. “This drought looks like it will have the most severe effect on the foliage of any I have seen in 16 years. Even oaks are showing signs of stress, and they are normally drought-hardy trees.”