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Columbia Missourian

Warm days, cool nights make for colorful fall foliage

By Cassidy Richardson
September 22, 2011 | 1:50 p.m. CDT
Autumn begins this Friday morning, and though we may see less of a change of colors this year, some leaves are beginning to turn.

COLUMBIA — Autumn begins Friday morning, and some leaves are already turning bright red, deep purple and yellow.

Although the hot, dry spell this summer could make for a less vibrant fall than usual, Ann Koenig, an urban forester for the Missouri Department of Conservation, expects the color of leaves this fall to be average when compared to other years.


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"With the dry spell that we had in the summer, that might dampen fall color because trees might lose their leaves before they have a chance to turn color," Koenig said. "But our fall has been good so far, so I would say another average year."

Stephen Pallardy, an MU forestry professor, said though the weather year-round does affect the vibrancy of fall colors, sometimes a small drought or dry spell provides for a color-intense fall.

"A mild drought sometimes will actually give you the potential for a somewhat better fall color," Pallardy said.

When talking about fall colors, he means the red and purple leaves, he said. The yellow-turning leaves, Pallardy said, will always turn because yellow pigments are simply unmasked during the fall. The reds and purples, however, are newly-created pigments. So the weather during color formation and peak color time is more significant than the weather during the summer, Pallardy said.

"There is a period of time they are prone to develop colors, but weather at peak time determines how intense the colors get," Pallardy said.

Koenig said the weather relates to the color of the leaves because of the sugar formed in the leaves.  She said the sugar in the leaves is formed during bright, sunny days. If the nights remain warm, the sugar disperses into the tree, and the colors are not expressed. If the nights are cool, the sugar gets trapped in the leaves and shows itself through the colors.

Pallardy agrees that bright, warm days and cool, crisp nights are prime weather conditions for a vibrant fall.

"The best conditions are temperatures in the 60s and bright sunshine during the day and 40s at night," Pallardy said. "This has to happen over a period of several days and nights, though."

The warm days and cool nights experienced recently put mid-Missouri on track for the peak color week, which is the third week in October, Koenig said.  

Although Columbia is not in its peak week for fall color yet, it is easy to see the trees are already changing. Pallardy said he saw several trees already turning colors as he was walking at MU on Thursday morning.

Koenig said what we are seeing right now are the Virginia creepers, walnuts, sycamores and dogwoods.

The Virginia creeper, a woody vine, is usually the first to turn and will continue to turn red throughout autumn. Walnuts and sycamores are beginning to fade and turn yellow but right now only have a yellowish-green tint. Dogwoods will eventually peak at red, but for now they are just starting to blush a purple color.

Pallardy said he has also seen red maples and sumacs already turning colors.

"But the ones that are noted for are sugar maples and sassafras," Pallardy said. "They will turn in the next two to three weeks."

After turning colors, freezing temperatures and wind will cause the leaves to fall. Pallardy said the peak leaf fall for Columbia is the second week of November.

Columbia has at least a few weeks to enjoy the bright colors of the turning leaves.