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Question from Codi (received 8/1/20) -

What is this on my young Washington Hawthorn? It was covered in ants. I was able to get rid of the ants, but I think they caused a burl, possibly. At least I am hoping that's what it is.

Answer from Dr. Mike Kuhns, USU Extension Forester and Professor (sent 8/3/20) -

Codi,

I think that your hawthorn likely has a fungal disease called cedar-hawthorn rust. This is similar to cedar-apple rust, which is more common. Diseases like these have two hosts, in your case a juniper or “cedar” and a hawthorn.  The fungus takes on a certain look and form in one host versus the other host. It attacks one species with a kind of spore produced by a certain fruiting body. Those spores can only attack the alternate host. Once they do this they produce a different spore from a different fruiting body that infests the original host. You can spray with fungicides if it gets too bad for you.