October 1, 2001 | By: Aimee D. Heald

Many Kentuckians have been waiting all year to see the brilliant, diverse colors fall brings to the Commonwealth’s landscapes. Doug McLaren, University of Kentucky forestry specialist, said the peak viewing time will be around the second and third weeks of October.

Since Kentucky has such a diverse climate and soil composition, many tree species common to both northern and southern states grow here. This provides a variety of fall colors for people to enjoy as they walk or drive through state and local parks and national forests. Kentucky nature sanctuaries and arboretums also have many tree species that put on a brilliant fall color show.

“Maple, dogwood, black gum, oak and sassafras trees produce various shades of red color,” McLaren said. “Trees that provide a range of orange and yellow colors include yellow-poplar, birch, hickory, beech and white oak.”

McLaren said that since black gum and sumac trees shut down chlorophyll production early, they are the first to reveal fall color. Both change from green to red, leaf by leaf. No leaf seems to be all green or red at the same time, giving a spotty appearance throughout the trees.

What actually makes the leaves change color? McLaren said the fall colors have been in leaves all along, but they have just been masked by chlorophyll, a green pigment that combines with sunlight to produce food for tree growth.

“This rebirth of color is caused by fewer hours of daylight, not ‘Jack Frost’," he said. “A ‘chemical clock,’ activated by shorter days tells, trees to shut down chlorophyll production in preparation for winter. So trees use chlorophyll faster than it's produced. This removes the green mask and the brilliant fall color show begins.”

When the tree's leaves completely shut down chlorophyll production, a layer at the base of the leaf, called the abscission layer, forms. In time the leaf will fall off the tree branch at this point, leaving only the bud with next year’s leaves and flowers to wait for Spring’s signal to bloom and grow.


Doug McLaren 859-257-2703