[IUFRO RG 7.03 FORENT] Fwd: Oozing Black Spots on Limbs of White Oak

Hello forpathers and forenters, Below are a couple of pictures sent to me by a local arborist, wondering what’s going on on the main limbs of a white oak. I am contacting you because I find that this kind of very localized bark discoloration/staining is quite common in oaks. I’ve always suspected these were very small, localized infections by some species of Phytophthora, like citricola, citrophthora, etc. but I’ve never verified. Whatever it is, it seems to me it never goes anywhere, i.e. the lesions remain very small and do not have any serious impact on the host. Does anyone else actually know what these are? It would be of great interest to me personally, in addition to providing an answer to the arborist. Cheers! Enrico [cid:clip_image002.jpg] Pierluigi (Enrico) Bonello Professor Department of Plant Pathology 201 Kottman Hall | 2021 Coffey Road Columbus, OH 43210 614-688-5401 Office | 614-292-4455 Fax bonello.2@osu.edu<mailto:bonello.2@osu.edu> | http://plantpath.osu.edu/bonello Center for Applied Plant Sciences | http://caps.osu.edu Translational Plant Sciences Graduate Program | http://tpsgp.osu.edu Environmental Science Graduate Program | http://esgp.osu.edu/ Infectious Diseases Institute | https://idi.osu.edu/ The STEAM Factory | https://steamfactory.osu.edu/ [cid:63D7C442144D594B812817CE094C4658@osu.edu][cid:4909276BEC6FCF47A83D546F1FA8649A@osu.edu]