|Bark has brown weeping patches in joints. What can I do?
|Answer from NGA
May 3, 2010
|Branch borers attack cottonwood trees and it sounds as though that's what you are finding in the crotches of the branches. Here's the lifecycle: Adults lay eggs in the crotches and galls develop. The escaping sap is caused by the borers making holes. Adult beetles emerge from April to June and feed on the foliage of the tree before laying eggs in niches gnawed in the bark. Usually the damage is minimal and the insects move away on their own in a year or two. While you can spray your tree to kill the adults, if the tree is very large, you'll want to hire an arborist to thorughly spray the tree. Best wishes with your cottonwood.
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