Released May 15, 2008
MANHATTAN, Kan. - Damage is showing up on some central U.S. trees that have relatively smooth, thin bark. They include the ash, honeylocust, linden, maple, oak, willow, and all region-hardy fruit trees.
"Late spring to early summer is when bark injured by wintertime sunscald finally starts to look sunken and discolored - even though the damage probably occurred weeks or months earlier. Eventually, that bark will crack and then slough off," said Ward Upham, Master Gardener program coordinator for Kansas State University Research and Extension.
In many cases, the trees can recover, he added. But, they will need extra care for a long time.
They´re injured because thin, sun-exposed bark can break dormancy - lose cold hardiness - much earlier than it should. So, any later cold weather before spring can freeze the newly activated cells.
Sunscald typically develops during late winter´s occasional warm, sunny days, Upham said. Due to the position of the sun then, the injury happens on the south or southwest side of the tree.
"Research in Georgia showed just how hot the sunny side of a trunk can be then," Upham said. "One study found that the southwest side of a Georgia peach tree in winter will be up to 40 degrees warmer than the shaded side."
The younger the tree, the more serious the impact of sunscald can be, the horticulturist warned.
"In fact, if you plant a thin-bark tree this year, you also should protect it with tree wrap - from ground level up to where it starts branching," he said. "Wrap it some time next October or November."
The only way to help trees already hurt by sunscald is to try to protect them from further stress.
"If nothing else, make very sure they get enough water during dry periods," Upham advised.
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http://www.oznet.ksu.edu/news/
Contact: Mary Lou Peter-Blecha, mlpeter@ksu.edu
