This question might be better on tree site but here goes. At my work we have to make sure there are no suckers growing on trees and some of the trees get these dime size wart like growths covered in buds. If you just snip off the sucker growth they still make more buds. So what I have had success with is snipping off the wart like growth. I'm not sure what these growths are and think they might possibly grow into burls. I tried to look up what causes them but not much is known. I'm kind of concerned if it's a disease I might spread it to other trees. As we don't have any kind of sterilization policy at work. Maybe I should just go and spend a dollar on some alcohol wet wipes to clean my pruners with. Mainly we deal with commercial clients who spend zero dollars maintaining trees. I see so many trees with problems. I tell my ops manager whenever I see something but nothing ever gets done.