Question about Phytophthora bleeding canker on honeylocust

Attached please find a picture of an ozzing canker near the base of a 20-25 year old honeylocust in our residential yard. I have been told by an arborist (who saw the pic) that this was most likely a Phytophthora canker and gave recommendations including chiseling out, systemic fungicide, and avoiding sprinkler from hitting. When I look online I see confflicting recommendations from different university extensions-sopme say this can't really be treated, others say to use a fungicide. What do you think?