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Cold snuffs blaze of color

Wed., Oct. 28, 2009

Autumn trees’ muted look is a result of this month’s hard freeze, experts say

If it seems to you the color in this year’s fall leaf crop has been less than glorious, you are right.

Plant experts Tuesday said the hard freeze that struck the Inland Northwest from Oct. 10 through Oct. 12 damaged or killed leaves on many trees and probably caused other trees to drop leaves more quickly than normal.

“We were robbed of our fall color,” said Charles Cody, plant growth manager at the Washington State University School of Biological Sciences.

“The fall color on campus this year was disappointing to say the least.”

Across the region, trees that normally have good color in October never got a chance. Their leaves were still green when the freeze hit, stopping the botanical process of color change and leaving behind only dried green or brown leaves.

Those showing the most leaf damage were horse chestnut, catalpa, dogwood, ginkgo, linden, sweetgum, sycamore, locust, aspen, crabapple, serviceberry, fruit trees, willow, black walnut and Japanese maple.

Leaves on many trees froze to their branches and are continuing to hang without changing color.

Other trees had partial damage and inconsistent color, including Norway maple, sugar maple, oak and birch.

“The color is definitely off this year,” said Alan Tower, of Tower Perennial Garden in southeast Spokane. “Normally, fall is much prettier.”

He said a row of gigantic black walnuts at his nursery froze when the polar front hit, and as temperatures warmed up during the day, the dead, green leaves “rained down” in a few hours. Normally, the leaves turn a brilliant yellow.

While the low reached 20 degrees at Spokane International Airport, Tower said his nursery was 18 degrees.

Cody said it was even colder in Pullman, where large maples saw substantial leaf damage.

Leaf color develops as nights get colder and days get shorter. But warm weather in September, including a 90-degree high on Sept. 23, didn’t prepare the trees for the freeze.

“Basically, the leaves had not had the time to do their changing,” Cody said.

Experts said they doubt the freeze will cause any lasting damage, although the cold snap might inhibit early bud growth next spring. Also, the stress of an early freeze could make plants vulnerable to harsh winter weather.



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