Whilst some galls are produced by insects laying eggs in plant tissues and the resulting larvae causing abnormal growths, Crown Gall is caused by a bacterial infection. There is no cure, so it is a good idea to catch it whilst small and chop the growth out.
26/08/21. Suspicious looking, slug-eaten fungus at the base of a sycamore tree trunk! is it Beef Steak fungus? It’s so very red. The pessimist in me says that the tree is on it’s way out