These look-alike proliferation tumors slough off on the most magnified photo in the group (1st photo in the group, right side). The tree host species is red oak Quercus rubra.
I am not convinced it is Agrobacterium. These proliferations do not look like the classic symptoms of that bacterium.
It might be possible it is a mixed infection bot fungal and bacterial. My first thought was it could be Pseudomonas savastanoi pv. fraxini but this pathogen should be found infecting only Ash.
I looks like Ash disease caused by pv. fraxini indeed. May be, it is a new pathovar or Pseudomonas savastanoi...?
You might be right Alex. It is possible. I'll try to arrange samples to be sent to a plant disease diagnostic lab.
Hi, tree burls may be caused by an injury, virus, bacterium or fungus. It is often impossible to determine the primary cause.
Regards, Franci
I believe you are right Franci . . . somewhere I thought (hoped) it could be some typical pathogen associated with these symptoms. It looks so interesting in the way it is deployed on the bark and it almost seems like it was concentrated insect piercing that created physical wounds and then allowed infection with some vectored pathogenic agent.
What about cutting wounds? Perhaps they are entry points for pathogen(s)? View your pictures (for example, 4). Proliferation tumors are above and below the trimmed branches.
Try to isolate from the bark tissue. Symptoms look like galls, maybe you should look for Agrobacterium.
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