Orange powder on pine tree

Asked June 3, 2019, 1:05 PM EDT

I have 3 old pine trees in a group in my yard. This year one of the trees have 2 small (1 - 2 inches) "bumps" with orange powder on them on the main trunk 2 ft from the ground. The bark on these bumps has gone and there is just orange powder plus fresh resin. What is this and what is the best way to cure it ?

Lincoln County Oregon forestry tree health

1 Response

Are these shore pines?

While I am not 100% sure from the picture, this looks like Western gall rust (caused by the fungus Endocronartium harknessii). It causes a distinctive roundish gall or swelling on branches and, occasionally, on the main stem.

This is one of the most common diseases of shore pine, yet it can be very patchy in distribution because it is closely associated with the microenvironment. A similar gall rust can also affect pine trees. See page 13 of this publication: https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/em9008.pdf

The primary management of western gall rust involves pruning infected branches or culling heavily infected trees and since this looks like it is on the main truck on the tree, I would definitely keep an eye on it. You may even want to contact a certified arborist to do a hazard tree assessment if this tree is close to structures or areas that people frequent, many of them will do a free estimate. You can find arborists in the area here: https://www.treesaregood.org/findanarborist