Leaves’ colors just beginning to turn

DIXON – As October heads to its midpoint, changing fall colors will beckon drivers to head out on the highways.

While there still are a few weeks before the peak of fall color arrives, there are some changes happening now in Winnebago, Stephenson and Carroll counties.

According to the Illinois Office of Tourism’s Enjoy Illinois website:

• The majority of the urban and rural trees are still green, but the amount of vibrant yellows increases daily, with honey locust, walnut and hackberry tree leaves starting to turn yellow, and some cottonwoods just starting to turn.
• Sprawling grapevines are turning yellow and joining the brilliant reds and scarlets of Virginia creeper vines and smooth sumac and gray dogwood bushes.
• Some of the sugar, red and silver maples are turning crimson or yellow earlier than the others around them.
• Hackberry and walnut trees are showing golden yellow colors in the Carroll County area.
• Some of the poison ivy vines on tree trunks are starting to show burgundy red colors.

According to the Illinois Department of Natural Resources, Illinois’ fall color season lasts several weeks, normally starting in northern Illinois counties by the third or fourth week in September. Leaf color begins to change during the second week in October in central Illinois and by the last two weeks of October in the southern part of the state. The peak of fall color in Illinois normally occurs by mid-October in northern and central Illinois and by late October or early November in the southern third of the state.

Other facts about leaves’ colors as provided by the IDNR:

• Leaves change color in autumn as the hours of daylight decline and the angle of the sun gets lower. The pigment chlorophyll is present in huge amounts in leaves during the spring and summer. Chlorophyll appears to be green because it reflects the green part of sunlight. Chlorophyll absorbs energy from the other colors in sunlight and uses it to transform carbon dioxide and water into sugars the tree uses as food.
• As the duration of daylight and the angle of the sun decrease in late summer and fall, chlorophyll production begins to disappear. Carotenoids begin to appear as yellow and orange colors in the leaves. The yellow carotenoid is called xanthophyll, and the orange pigment is carotene.
• Anthocyanins form in the leaves of some tree species in the fall and produce red and purple shades. These pigments develop from the sugars trapped in leaves. On warm, sunny fall days, the leaves produce sugars. At night as the air cools, plant transport slows, and the sugars are unable to be transported from the leaves. The brighter the fall sunlight, the more sugars are produced and the more brilliant the colors. Anthocyanins react to soil chemistry, affecting the color displayed in the leaf. In acid soil, the leaf may be red in the fall. If the same type of tree was growing in alkaline soil, its leaves may be purple in the fall.
• Weather is the most important factor in how colorful leaves will be in the fall, according to the IDNR. Ample rainfall in the summer leads to healthy trees with many pigments and sugars in the leaves. These leaves will provide beautiful fall colors. Bright, sunny skies in late summer and early fall lead to more red, yellow, bronze and orange shades. Numerous cloudy days may cause the production of more gold and yellow tints. In drought conditions, leaves may drop from the trees without much color change at all. If the temperatures turn too cold, leaves can die before they change color.
• Red oak, sugar maple, flowering dogwood, persimmon, sweet gum, sumac and tupelo gum trees produce deep red, bronze and orange shades, according to the IDNR. Trees with bright orange and yellow tints include sugar maple, cottonwood, wild black cherry, ash, birch, hickory, sassafras and tulip trees. Deep purple and red shades are the fall colors of tree-climbing vines, such as Virginia creeper and poison ivy.