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If Trend of Overcast Skies Continues, Optimal Leaf Color for High Country Autumn May Suffer in Coming Weeks

By Mark S. Kenna

Photo by Andrew Pennestri
Photo by Andrew Pennestri

August 16, 2013. The High Country has experienced a particularly wet summer. If these conditions continue it could affect the vibrant color of the autumn leaves, Howard Neufeld, professor of biology at Appalachian State University, said.

“During this time of year, trees become sensitized to the shortening of days and temperature,” Neufeld said, adding that cloudy and rainy conditions bring the yellow and orange fall colors but not the red.

Unlike red pigment, the yellow and orange pigments are underneath the green pigment, whereas the red pigment has to be produced by the tree, Neufeld said.  

This pigment is at its most vibrant point when the transition to fall has more sunny days than cloudy. If there is no sunlight for the tree to undergo photosynthesis, the red-colored leaves will be dull.

But this does not mean that the fall colors will be tepid this year, there are still another two months for optimal leaf-color weather conditions, Neufeld said.

For “leaf lookers,” the best time for the fall colors will be in the first week of October. 

Starting sometime in September, look to Neufeld’s “Fall Color Report” on the ASU Biology website.