Dear Enrico

It is very good to hear from you, thanks for sending nice photographs.

Is this on Quercus robur?

I have seen very similar symptoms in the UK on Q. robur although weeps from the lower region of stem branches. Although these type of symptoms are not typical of AOD (Acute Oak Decline), the cankers and weeps tested positive for the AOD bacteria and so we assign the cause of the cankers to bacteria.

Do you know if there is any insect association with the cankers in Ohio?

We could send you swabs, you could swab affected trees and post them back to us for RT-PCR assessment for AOD bacteria, if that is of help to you.

Additionally, there is an apparent emergence of Drippy blight in Colorado (Lonsdalea quercina). I think it would be useful to test for that in the case you mention in Ohio, it could be important. Rachel Sitz and Ian Pearse are contacts for this expertise (Rachael.Sitz@colostate.edu; ianspearse@gmail.com).

I hope this is helpful,

Best wishes,

Sandra

Dr Sandra Denman
Principal – Oak Declines: Senior Pathologist
Centre for Ecosystems Society and Biosecurity
Forest Research
Alice Holt Lodge
Gravel Hill Road
Farnham
GU10 4LH

Tel: 0300 067 5640
Email:sandra.denman@forestry.gsi.gov.uk

https://www.forestry.gov.uk/fr/INFD-84RB3W

From: rg70300-forent [mailto:rg70300-forent-bounces@lists.iufro.org] On Behalf Of Bonello, Enrico
Sent: 17 November 2018 18:49
To: rg70200-forpath@lists.iufro.org; IUFRO RG 7.03.00
Subject: [IUFRO RG 7.03 FORENT] Fwd: Oozing Black Spots on Limbs of White Oak
Importance: High

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

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 | 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/

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