FALL FOLIAGE COLOR

By Kevin Starr
Lincoln County Cooperative Extension Agent



I had the opportunity to go to the mountains last week for some training. Some of the trees were starting to show significant color. No man-made attraction is more beautiful than the show that nature puts on in the North Carolina mountains. But why do leaves turn certain colors and why are they showier in certain years? The explanation for that follows and is provided by Dr. Robert Bardon, Extension Forestry Specialist from N.C. State University.

Leaves get their green color from a pigment called chlorophyll. This pigment, which is necessary for food production, is found in numerous cells through out the leaf. Along with the green pigment, leaves also contain yellow or orange carotenoids. Most of the year, these yellowish colors are masked by the greater amount of green coloring. But in the fall, partly because of changes in the period of daylight and changes in temperature, the chlorophyll breaks down, the green color disappears, and the yellowish colors become visible.

The red pigment, anthocyanin, appears later in the growing season as a result of a combination of factors. Anthocyanin is produced from high concentration of simple sugars in the leaf cells and warm sunny days followed by cool nights with temperatures between freezing and 45o F. Variations in leaf colors are due to the mixing of varying amounts of the chlorophyll and other pigments in the leaf during the fall season.

The most vivid colors appear after a warm dry summer and early autumn rains that prevent early leaf fall. Long periods of wet weather in late fall produces a rather drab coloration. Some of the most startling color combinations are to be found in the leaves of red and sugar maples, sassafras, sumac, blackgum, sweetgum, scarlet oak, sourwood, and dogwood.

As the fall colors appear, other changes are taking place. At the base of the leafstalk where it is attached to the twig, a special layer of cells develops and gradually severs the tissues that support the leaf. At the same time nature heals the break, so that after the leaf is finally blown off by the wind or has fallen from its own weight, the place where it grew on the twig is marked by a leaf scar.

Don’t forget that those fallen leaves are a valuable resource when they are composted and mixed with our heavy clay soils. If you need more information on composting, please call Cooperative Extension at 704-736-8452.