By Keith Mickler, County Coordinator and Agriculture Agent
Fall has finally arrived and with that arrival, what does mother nature do? She knocks the dust off of her watercolor set and starts painting the landscape with hues of red, yellow, purple, burgundy, pink, or whatever color suits her fancy at the time. The grandeur of fall is revealed in the beauty of all these colors. But what causes this mixture of colors?
It comes from a chemical process that takes place in the trees as the seasons change from summer to winter. From the time the leaves emerge in the spring, all the way until fall they serve as factories producing most of the food necessary for the tree’s growth. This food-making process takes place in the numerous cells found inside leaves that contain chlorophyll.
Chlorophyll gives the leaf its green color most of the year. This extraordinary chemical known as chlorophyll absorbs sunlight which is the energy source used in transforming carbon dioxide and water into carbohydrates such as sugars and starch that feed the tree.
The colors start to show
In the fall, when the days start to get shorter and temperature start to drop, the leaves shut down their factories. The chlorophyll inside the leaf breaks down and the green color fades away leaving yellow too orange, red to pink, or just brown thus producing the color wheel for fall.
But wait, there’s more to it than just that. These colors are called pigments. Some of the pigments found in the leaves are carotenoids, which create yellow and orange leaves, some are anthocyanins that create red, pink, or purple colored leaves.
You see, when the weather starts to change in the fall, some trees break down all the green pigment leaving not one drop of it inside the leaf. Thus, the beautiful yellows, oranges, and reds come through, such as the reddish and purplish fall colors found on trees such as dogwoods, sweet gums, and sumacs, the brilliant orange of sugar maple, or the golden yellow of ginkgo. All these colors arise from the mixing of varying amounts of chlorophyll and other pigments in the leaf.
Other changes that take place in the fall
Scars, leaf scars to be exact. These scars are formed at the point where the stem of the leaf is attached to the tree. A layer of cells develops and gradually cuts the tissue away that support the leaf. During this same time, the tree seals the cut, thus when the leaf is finally blown off by the wind or falls from its own weight, it leaves behind the leaf scar. I guess this is like a mic drop, all done.
Color intensity is affected by the weather
Temperature, light, and water supply have an influence on the degree and the duration of fall color. Rainy and/or cloudy days will often help increase the intensity of fall colors. Furthermore, low temperatures but above freezing favor anthocyanin pigments producing the bright reds leaves seen hanging from the maple trees. Sadly, though, if we have an early frost expect that brilliant red color to be puny. The best time to enjoy mother nature’s water coloring masterpiece is a nice clear and cool autumn day.
Treemendous educational event
Want to learn more about trees? If so, come join Terry Paige, City of Rome arborist and yours truly, Keith Mickler, on Halloween day (Thursday, Oct. 31) at Bridgepoint Plaza starting at noon for our annual tree walk around Rome. You never know we might run smack into some anthocyanin, chlorophyll, carotenoids, or dirty brown pigments lurking about. Come enjoy the educationally fun lecture, I promise it want hurt a bit.
Keith Mickler is the County Coordinator and agriculture agent for The University of Georgia/Floyd County Cooperative Extension. Located at 12 E. Fourth Ave., Rome, GA 30161 (706) 295-6210. Office hours are Monday-Friday from 8 a.m. to 5 p.m.