What is wrong with a mature ponderosa pine with globs of sap on the bark on the main trunk and an overall gray-green color that is starting to turn brown?

October 17, 2011 Print Friendly and PDF

A ponderosa pine with symptoms such as globs of sap on the trunk and a pale green color may be the result of invasion by mountain pine beetles, which generally attack pines in August. The popcorn-like masses of sap are pushed out of the tree as the beetles work their way in. The beetles transmit a fungus into the tree that will often kill it during the following season. This “blue stain fungus” blocks the vascular system within the tree, interrupting the transmission of water and nutrients up and down the main trunk, thereby causing tree death. To prevent infestation of other trees from the beetles, the recommendation is to spray with formulations of carbaryl (Sevin) or permethrin (follow label directions when making chemical applications). These can be applied to trees during early summer, which will kill the beetles if and when they attack. Since the ponderosa pine tree is dying and is probably still host to a myriad of beetles that will emerge later in the summer, it can be cut down and the logs buried, burned, or debarked and the peelings disposed of to eliminate any beetles.

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This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.