fuzzy white on white pine

Asked April 8, 2016, 8:43 AM EDT

Wondering what this is called and how to treat it.

Hennepin County Minnesota pine tree health diseases of evergreens

1 Response

Thank you for the question. Due to the limitations of the photo we can't be certain what is causing the white patches on your tree, however, you may be able to use our online tool "What's wrong with my plant" to figure it out. Our best guesses would be diplodia shoot blight or white pine blister rust, but to be sure, have a professional arborist come to give a diagnosis if the tree is valuable to you and you want to use chemical treatments.

Diplodia shoot blight is a fungal infection spread in wet weather by wind, splashing rain, animals, insects, and pruning tools. Stressed, weakened trees are most susceptible to this infection. It can be treated by improving growing conditions with proper watering, mulching around the base of the tree in a doughnut shape, and pruning out affected areas during dry weather. It can also be treated with fungicides but an accurate diagnosis must be made prior to treating with chemicals to avoid harming the rest of the tree, pollinators, birds and other beneficials.

White pine blister rust is another fungal infection spread on cool moist air currents that infects Eastern white pine or other pines with needles attached in groups of 5. If there are currant or gooseberry bushes around, they can spread the fungus to the pine as well. Treatment is to prune out cankers, remove nearby currant and gooseberry bushes, and promote conditions that help the tree dry off quickly after getting wet. This would involve pruning lower branches, aiming sprinklers away from the tree, and only planting them where there is good airflow all around.

You will need to carefully inspect the tree after reading the link at the end of this paragraph. You may be able to figure it out based on the photos and descriptions of the diseases.


Good luck and thank you for contacting Extension.