Will spring drought put a damper on our fall colors this year? Next few weeks may decide

Autumn begins today with shorter, cooler days and the eventual arrival of bands of color overhead, as leaves turn and drop.

When does the show start?

"It's a year-to-year thing," said Julie Janoski, plant clinic manager at the Morton Arboretum in Lisle. "Being so dry this year is definitely impactful."

The peak for fall colors in the suburbs usually arrives around Oct. 20, but the exact timing and intensity depends on the weather going forward, location and other factors.

Black walnuts and eastern cottonwoods already have begun to drop leaves. Honey locusts are turning yellow. Freeman's and Autumn Blaze maples are showing early colors this year.

"I think they're responding to the drought," rather than disease or insects, said Shawn Kingzette, district manager for The Davey Tree Expert Co.

Curled, yellowing or dropping leaves are another sign of stress from the hot, dry summer as trees begin to shut down, according to Nan Buckardt, director of education for the Lake County Forest Preserve District.

A bicyclist rides through a backdrop of fall color at Busse Woods in Elk Grove Village. Experts say the dry summer could have a negative effect on the brilliance of fall color this year. Daily Herald File Photo, 2003

Generally speaking, trees that received more water this summer likely will be more colorful than those in drought areas, observers say. But not always.

"We're never quite sure how vivid things will be," Janoski said. "If you get cool nights and warm days, you get better color."

Morton Arboretum has 1,700 acres of trees and soon will begin posting a fall color report on its website to show what has begun turning and to what extent.

"We get a really nice progression of color starting in the middle of September," Janoski said. "But what is a typical year anymore?"

Northern Illinois is running at about a 7-inch rainfall deficit, she said, but watering trees until the ground freezes will help them in the long term.

The most brilliant colors in fall occur when sugars bind to the other pigments in leaves, which are hidden during the growing season by the intense green of chlorophyll, according to Buckardt.

When trees are stressed, they shut down to reduce the amount of water and nutrients they need, she said. As a result, there is less sugar available when the chlorophyll begins to break down.

Eye-popping colors occur when trees shut down quickly, such as after an early hard frost. When that happens, sugar is trapped in leaves instead of being pulled into the trunk.

  Colorful trees surround the sky bridge near Elk Grove Village in 2019. The peak of fall colors usually arrives in the suburbs around Oct. 20, but much will depend on the weather over the next few weeks. Mark Welsh/, 2019

But since trees have been stressed all summer, there likely isn't much extra sugar available and an early freeze may not translate to brilliant colors, Buckardt said.

The timing of peak color can change depending on weather conditions leading up to the annual show, said Scott Kobal, plant ecologist with the Forest Preserve District of DuPage County.

"Bright, sunny, relatively warm days and cool but frost-free nights are the key weather ingredients in late summer and early fall for the best fall colors," he said.

According to Kobal, an early frost speeds the fall of leaves and reduces the duration of color. Cloudy days and warm nights also can reduce fall color.

Although DuPage County hasn't had as severe of drought conditions as Lake and McHenry counties, Kobal anticipates a "somewhat subdued" amount of color this fall because of dry conditions during the growing season.

That observation comes with an asterisk.

"The weather we experience over the next several weeks is the key to the intensity of all color, so things can change based on these conditions," he said.

Buckardt expects this season's colors earlier and not as brilliant as in many years.

"That said, nature has fooled me more times than I care to admit," she said.

Enjoy Illinois is working with the Illinois Department of Natural Resources to create a fall color report, but it likely won't be live until the end of the week at the earliest.

  A single maple leaf hangs on at the Morton Arboretum in Lisle. The dry spring and summer could make this year's fall colors a little less bright, experts say. Jeff Knox/, 2019

Neighboring states are in a similar situation.

Peak times in Indiana typically are the second and third weeks of October but can be as early as late September or as late as November, said Amy Howell, director of marketing and communications with Visit Indiana.

In Michigan, fall changes are a bit behind schedule, with color expected from mid- to late October, said Kathleen Achtenberg, senior communications strategist at Michigan Economic Development Corp.

The state's 19 million acres of forests and colorful canopies are an element of the "Pure Michigan" fall campaign to encourage travel. A fall color map shows the best time to view in various parts of the state.

Colorful trees along the trails at the Morton Arboretum in Lisle. When will the fall colors peak in the suburbs? Experts say it's a bit of a guessing game, depending on weather and other conditions, but the usual peak occurs around Oct. 20. Daily Herald File Photo, 2018

In Wisconsin, forests in central and northeastern portions of the state are right on target, but counties in the northwest and far southern part of the state are encountering drought conditions that may affect fall color, according to the state's Department of Natural Resources.

In some cases, trees may skip the color change altogether with leaves turning brown before falling. Travel Wisconsin has a fall color report listing estimated peak times by county.

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