Sorry to be a pedant with my first post but that looks to me like it is Acute Oak Decline rather than P.ramorum. On several sites I have been involved in the management of, this has resulted in significant levels of tree mortality where clusters of symptomatic individuals develop. There is a fair bit of info on AOD on the Forest Research website but unfortunately there is no concrete guidance on how to deal with infected trees, in your situation, given the targets present, my opinion would be to fell as a sanitation measure to try to minimise any future spread. If it is felled, it'd be worth finding out what recommendations FR have regarding dealing with the arisings. Hope that helps, Dave
