I spend a lot of time in the Unknowns, which means I see a lot of “Needs ID” observations with bacteria/viruses suggested as an ID. Perhaps the most common one is Bacterial Crown Gall (Agrobacterium radiobacter), a bacterium that causes tumorous growths on woody plants. I know some bacteria/viruses cause such distinctive symptoms on specific hosts that they’re reasonably identifiable without microscopy based on the host symptoms. But other symptoms are too non-specific to be attributed to a specific pathogen species without microscopy or other lab techniques.
So my question is, where does Agrobacterium radiobacter fall on that spectrum? If I see a big ol’ woody growth popping out of the side of some random tree, how certain can I be that Agrobacterium radiobacter is responsible? I’ve seen dramatically differing points of view from different sources, ranging from “these growths could be anything and no specific ID is warranted” to “I identify it as Agrobacterium radiobacter only if it’s on certain tree species” to “well it’s probably Agrobacterium radiobacter if it looks like all the other Agrobacterium radiobacter photos”. I’m looking for input from anyone who knows about plant pathogens- when you scroll through the thousands of “Bacterial Crown Gall” photos on iNat, do you think “yeah, those mostly look right”, or do you roll your eyes and think “there are dozens of pathogens that cause the growths in these images and calling them all one bacteria species is silly”?
I’ve personally been ignoring these observations, because I’m not sure what to do with them, but I scroll past so many every day that I figured I’d ask what the experts think about their identifiability. Thanks for any input!