Our annual fall foliage color display began a little later this season, as rainy weather and relatively warm temperatures seemed to have slowed the initial changes. Unfortunately, once the process begins, it goes way too fast. I expect peak color to occur around mid-October for mountainous areas in Greene, Ulster, and Delaware counties and maybe a week to two weeks later for towns in the valley. It only takes a few weeks to go from zero color to maximum color. The older I get, the faster this process seems to unfold each year. Roadside trees, which are usually under stress initially, are often the first to change leaf color. I have heard that some people predict less than an optimal display because the wet summer has caused many leaf diseases on trees such as sugar maples and several of our ash trees have already succumbed to the emerald ash borer. . There are conspicuous bare areas in our forests where entire ash groves have succumbed to this pest.
It is true that many sugar maples have already shed their leaves, a bit prematurely, but there are still many to display their typical golden / yellow hues. Other trees that are yellow in color include birch, aspen, beech, and some hickory as well as hops (ironwood) hornbeam. Some predominantly red tree species, such as the red oak, are among the last to change. Staghorn sumac shows its typical fiery red color and witch hazel is now bright yellow.
Red maples change color a bit earlier than sugar maple and many of them are already near the peak. The pigments that cause the color red, as well as various hues of purple, are called anthocyanins and they really need cooler weather to develop. These pigments actually form in the leaves at this time of year for reasons scientists don’t understand. They are unable to determine what function they play in the physiology of trees. The pigments responsible for the yellow / golden hues are called xanthophyll and carotenoids and they are present throughout the season, but are masked by the green pigment, chlorophyll. It is only when the tree begins to form an abscission layer of cells, cutting off the water to the chloroplasts, that the yellow color becomes evident.
Sun exposure also affects color. The Virginia Creeper Common Vine turns yellow on shaded forest soil, but takes on a bright red / purple color when the vines are growing in full sun. Poison ivy behaves the same way. My favorite herb, American ginseng, takes on a beautiful golden yellow color that seems to glow even at dusk. Some have speculated that the brilliant fall color of ginseng allows worthy pickers to find it only when the roots are fully ripe and the red berries have already fallen. If you come across any ginseng in the forest that still has bright red berries, please remove the seeds (usually two white seeds) that are inside each berry and plant them nearby, no deeper than ¾ inch in the ground under the duff layer. When I find ginseng berries, I usually eat the pulp of the berries and spit out the seeds for planting. However, I cannot suggest that you do the same, as there is a “ginseng-like” plant called “Jack in a Pulpit” that also has bright red berries right now. Ingesting any part of this plant, including the berries, will severely burn your mouth and throat. It is not a good idea to taste any wild berries you might come across, unless you are quite sure what species of plant it is.
Left to reproduce on its own, ginseng has fairly poor success, with perhaps less than one to two percent of the seeds becoming mature plants. This process also takes about ten years, but if you carefully replant the seeds, the success rate can reach 85%. There are some rather beautiful, but also invasive plants that produce pretty berries at this time of year. Asian sweet and sour is one of those plants that I have a hard time controlling on my property, where it has become a serious weed. These twining, woody vines can form dense thickets that crowd out other nearby plants. The bittersweet red berries are encased in a bright yellow husk that splits after frost and stays in place framing the bright red berries. It’s true that it’s pretty, but it’s also a pretty serious weed in our woods!