Weather Linked to Bark Splitting in Trees - by Chris Starbuck

First posted on 09-02-2008

COLUMBIA, Mo.- Cases of bark splitting on trees, perhaps due to excessive trunk expansion spurred by this year’s heavy rains, have been reported in some areas of the state, said a University of Missouri Extension horticulturist.

“We don’t know what exactly is causing the bark splitting, but maples seem to be the most commonly affected. Environmental conditions over the past year have probably contributed to this,” said Chris Starbuck.

“It is possible that some of the cracks may have started as a result of the Easter freeze of 2007 or some other damaging event and may be developing now due to the rapid trunk expansion caused by this year’s moderate temperatures and ample rainfall,” he said.

Bark splits are not likely to be fatal to trees, but in some cases they allow entry of disease organisms, which can lead to decay.

“Do not paint or try to seal a split with paint or tar,” Starbuck said. Research has shown that tree wound paints are not effective in helping the tree to callus over.

Cleaning the edges of the wound, known as “tracing,” can help the healing process. Use a sharp knife to trace around the wound no more than one-half to one inch back from the split bark. Carefully remove the bark from inside the traced area, leaving smooth edges.

Do not fertilize newly planted trees late in the growing season. This may promote new growth and increase chances of winter injury, including bark splitting.

Bark splits often close over completely, leaving a slight ridge in the trunk where callus tissue has formed