Identification: Fungus or infection?

Hello,
We've just moved to Port Alberni, where we have a Prunus Tree (possibly a cherry) in our back yard with a thick coating of green slime on quite a large portion of it's truck. Is this cherry sap infection, or perhaps bacterial canker? It looks too gelatinous and green to be gummosis.
Should I worry about this spreading? I have several plum trees nearby that I'd like to keep healthy.
Should I cut down the infected tree, as there is so little healthy wood to cut back to?
Lastly, how common is this for my area? Hopefully I won't have this to look forward to often.




Thank you kindly!

 

It looks like gummosis to me.

 

Thanks David.