Evergreen dead branches white sap

Asked May 2, 2017, 10:34 AM EDT

I checked the diagnostics info and this could be white pine rust. Branches on the lower level are dying from the center out and loosing all pine needles. I also see white sap on the bark of the trunk. The tree is about 20 feet tall and it's effecting about 1/2 of the tree. From the bottom up. I could get a lot of info but not what I should do or how to stop it, don't want to loose the tree, it's about 30 years old. Pat

Hennepin County Minnesota white pine blister rust horticulture pine diseases

1 Response

Thank you for the question. It's hard to tell what's going on with the tree from the photo through the window but if you have researched the problem using our self diagnostic module and are pretty sure of your diagnosis, I will focus on control measures.
White pine blister rust requires white pine and, most commonly, gooseberry and currant shrubs to complete the full disease cycle. If your tree has the disease, it means that there are gooseberries or currants nearby. The shrubs can be as far as a mile away from your tree and still cause the problem. This paragraph from Clemson Extension describes it well: "This disease is caused by the fungus Cronartium ribicola. It is only a problem in ornamental pines when currants or gooseberries (Ribes species) are growing nearby. Currants or gooseberries are alternate hosts and are needed to complete the life cycle of the disease organism. The fungus attacks the living bark of white pine, first breaking out in blisters, which exude a secretion, later forming larger, bright orange-colored dots. These orange dots are filled with fungal spores that are carried to the alternate host, where it develops during the summer. Spores from the currants re-infect healthy pines. The disease spreads rapidly up and down the tree, killing the branches and the main trunk".
Control of the disease consists of cultural methods such as removing known currant or gooseberry shrubs within 1000 feet and then pruning out cankered branches and excise stem cankers by removing bark at least 4 inches above and below, and 2 inches on either side of discolored bark. There are no fungicides available to control white pine blister rust.
If you want to double check your diagnosis, consider having the tree evaluated by a certified arborist. Here's how to look for one: http://www.extension.umn.edu/garden/yard-garden/trees-shrubs/how-to-hire-a-professional-arborist/

Here are other disease fact sheets with photos that might be helpful:

Thank you for contacting Extension.