shelf fungus? maybe? without a pic, I couldn't tell that from oyster mushrooms...

but you can just strip them off (wear gloves- few of them are toxic, but I at least am kind of allergic to all molds and fungi) and then treat the area with a fungicide...

but it often means that the wood underneath is already dead- which rarely hurts a stubborn tree like a willow- most of the old ones I've met are at least partly hollow, but it's something to keep an eye on.

i just planted a willow trree so it is still young but i have some problems: One, the leaves are turning yellow. Is that from too little water? I dont live near any lakes....and Two, there are little orange spots on all the leaves. I have no idea what that could be. Could you help me please?

these trees need TONS of water especially if you in your 1-2 year of transplanting them.

I had planted a willow and 2 weeks later it died due to laque of water. Also try adding a transplantor to it every 2 weeks.