Thanks for your advice, I really don't mind the way the small burls look, in fact I think it adds some character. I was just more concerned about the health of the tree/risk of the burls spreading to my other trees. If the risk of the disease spreading to my other trees is low I am not too worried. I will be careful with tool cleaning, Thanks!In animals, a tumor develops when a cell (or group of cells) loses the built-in controls that regulate its growth, often as a result of mutations. Plants can experience the same phenomenon, along with cancerous masses, but it tends to be brought on via infection. Fungi, bacteria, viruses, and insect infestation have all been tied to plant cancers. Oak trees, for example, often grow tumors that double as homes for larvae.The good news for plants is that even though they’re susceptible to cancer, they’re less vulnerable to its effects. For one thing, a vegetable tumor won’t metastasize. That’s because plant cells are typically locked in place by a matrix of rigid cell walls, so they can’t migrate. Even when a plant cell begins dividing uncontrollably, the tumor it creates remains stuck in one place usually with minor effects on the plant’s health—like a burl in a redwood tree.
I wouldn't get rid of it myself it not something that is contagious, I like the looks of it myself
Thanks for your input, I truly hope so.There is nothing wrong with your tree. That is a perfectly normal growth pattern with cork bark Chinese elms.