What's this tree crust?

My Hawthorn tree hedge has a disease that creates swollen, crusty areas on some branches. I think it's cedar apple rust and plan to treat with organic antifungal. In the meantime, I have cut out the rotten spots, pruning back the hedge significantly. The trees were planted bare-root five years ago and are generally healthy. Please let me know if you have any idea whether this is cedar apple rust, or another disease, and how to treat. Thanks!
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