We live in Eagle River, WI. Over the last year we noticed that our pine trees...

Asked March 29, 2014, 6:38 PM EDT

We live in Eagle River, WI. Over the last year we noticed that our pine trees are dying, losing all of their bark. This is getting concerning and alarming. What could be causing this? They are not located in the same area on our property.

Vilas County Wisconsin forestry tree health pine trees pine tree health bark tree diseases evergreens dying

3 Responses

Losing bark can be a symptom of several possible conditions, and other information is needed to find the exact cause. Which species of pine is it? What type of soil does it grow in? Have you used any pesticides or herbicides in the area (including nearby lake or river)? Did you notice if the tree was browning from the top down or bottom up? Are there holes of tree sap around the base from insect exit wounds? Are there squiggly tunnels exposed on the trunk wood when the bark falls off? Does the bark fall off in the lower 6-8 feet or higher up the trunk? Have you notice beetles near these trees? Were they stressed by the drought or under water by flooding? All those would give more information on the cause. Each would narrow down possible causes. Without that, I can only give a best guess from the most common source of that sort of damage. The drought of 2012 weakened many trees and left them susceptible to insects, fungal infection, and just poor health. Northern Minnesota and Wisconsin has seen an increase in various Pine Bark Beetles. Their larvae tunnel under the bark and cut off nutrition to the top of the tree. Trees under attack brown from the top down. The tree responds to the attack by dropping plates of bark from the most damaged areas to expose the larvae tunnels. If that sounds like the problem, here is an excellent resource on diagnostics and treatment: Pine bark beetles http://www.dnr.state.mn.us/treecare/forest_health/barkbeetles/index.html Traits of various pine bark beetles http://www.caes.uga.edu/extension/lowndes/anr/documents/PineBarkBeetles.pdf You can also take pictures of the damage and samples of the bark and wood to your local Extension Office in Vilas County, at the Courthouse in Eagle River. I hope this information has been helpful. Please feel free to post more details for a better diagnostic, or take samples in to the office for an exact identification.

The trees are in sandy soil. We have not used herbicides or pesticides. I posted some pictures of the trees. There are 6 to 8 trees that are like this. Most of them are in the front of our house on a hill heading down to the lake.

Marilyn's answer is spot on, and I'm not sure that I have much to add to it. Without knowing more about the growing conditions, in particular the soils, it is hard to pinpoint a cause for this mortality. Unfortunately the photos that you submitted show damage that most likely occurred after the death of the trees rather than causing it. Once the tree becomes weak enough to have shed its bark, it has virtually given up its natural defenses and is on a steep decline.

The fact that these trees are located on a hill leading down to a lake would perhaps make them less susceptible to drought stress, but then the sandy soil might increase that risk, as sandy soil has relatively little moisture-holding capacity.

Wish I could be of more specific help. One important recommendation though is that if you see similar mortality on other pines, get those trees cut and removed from the site ASAP. Whatever the initial cause of mortality in this stand, standing dead trees can quickly become refugia for bark beetles. While normally bark beetle populations are low enough that trees can effectively fight them off by exuding pitch into their bore holes and galleries, when populations get high enough they can overwhelm and kill healthy trees. The links that Marilyn shared have good information about this risk.

Hope this helps.
-eli