Thursday, October 1, 2009

Take Steps Now to Prevent Sunscald on Thin-Barked Trees

By David Burton
University Extension


Homeowners who planted new trees this year, especially ones with thin bark, will want to protect the southwest side of the new tree this winter to protect it from sunscald.
Many young, smooth, thin-barked trees like honey locusts, fruit trees, ashes, oaks, maples, lindens, red buds and willows are susceptible to sunscald and bark cracks according to John Hobbs, agriculture and rural development specialist with University of Missouri Extension.
“Sunscald normally develops on the south or southwest side of a tree during late winter,” said Hobbs. “Sunscald and bark cracks can lead to the death of a tree if it is not given special care.”
According to Hobbs, sunny, warm winter days may heat the bark to relatively high temperatures. Temperatures in southwest Missouri may not reach the same extremes as in Georgia, but research done in Georgia shows that the southwest side of the trunk on a peach tree can be 40 degrees warmer than shaded bark in the winter.
“This warming action can cause a loss of cold hardiness of the bark tissue resulting in cells becoming active,” said Hobbs. “These cells then become susceptible to lethal freezing when the temperature drops at night.”
The damaged bark tissue becomes sunken and discolored in late spring. Damaged bark will eventually crack and slough off. Trees will often recover but will need some lots of extra care, especially watering during dry weather, according to Hobbs.
To prevent sunscald, the trunks of susceptible trees can be covered with tree wrap in October or November. Hobbs recommends applying tree wrap from the ground to the start of the first branches to protect recently planted trees.
“Tree wrap must be removed in March to prevent girdling and possible insect damage. Until the bark has thickened on young trees, they may need to be wrapped yearly,” said Hobbs.
Another product that can be used on the trunk is tree paint. White latex paint is often used in orchards to help prevent splitting and cracking by reflecting light and heat from the tree trunk. Due to aesthetic reasons, most homeowners are not interested in using tree paints.
Both tree paints and wraps can be found at local garden centers and nurseries.
For more information contact the nearest University of Missouri Extension center or call Hobbs at (417) 223-4775.

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