dutch elm disease picture and post made by: Joshua Leathers.

A post from an arborist group:

Customer treated several trees a few years ago for dutch elm disease himself (even though we do not have dutch elm disease here) using propanazole injections. This tree ultimately died and he cut it down and found this pattern. All the still living trees also have raised vertical sections in the same spots the injections took place like this running from the ground to the canopy in a straight line. Some of the lines actually started to split almost like stretch marks. What causes this? What is going on here?

picture and post made by: Joshua Leathers.