I am worried About my oak trees - Ask Extension
I have large oaks around
my house one appears to be making sap, one has white mushroom growths that then turn black and are hard as rocks.
Pictures...
Knowledgebase
I am worried About my oak trees #938372
Asked July 07, 2026, 12:11 PM EDT
I have large oaks around
my house one appears to be making sap, one has white mushroom growths that then turn black and are hard as rocks.
Pictures are from 2 separate trees
Is it possible to have someone come look at them?
Steele County Minnesota
Expert Response
These questions are assigned to UMN Extension volunteers all over MN. Geography usually prevents us from making house calls. Contact Steele County extension to see if any of their volunteers would be willing to do so. Scroll down to the Master Gardeners area.
https://extension.umn.edu/local/steele
Regarding the "leaking tree" see these web pages.
https://ask.extension.org/kb/faq.php?id=665875
https://yardandgarden.extension.iastate.edu/faq/sap-oozing-out-old-pruning-cut-my-tree-serious-problem
Regarding the mushroom like growths, see these web pages. Scroll down to Gandoerma
https://extension.psu.edu/oak-diseases
https://www.umass.edu/agriculture-food-environment/landscape/fact-sheets/root-trunk-rot-caused-by-ganoderma-applanatum-artists-conk
Have an arborist experienced with oak diseases to confirm this guess diagnosis.
https://extension.umn.edu/local/steele
Regarding the "leaking tree" see these web pages.
https://ask.extension.org/kb/faq.php?id=665875
https://yardandgarden.extension.iastate.edu/faq/sap-oozing-out-old-pruning-cut-my-tree-serious-problem
Regarding the mushroom like growths, see these web pages. Scroll down to Gandoerma
https://extension.psu.edu/oak-diseases
https://www.umass.edu/agriculture-food-environment/landscape/fact-sheets/root-trunk-rot-caused-by-ganoderma-applanatum-artists-conk
Have an arborist experienced with oak diseases to confirm this guess diagnosis.
