Posted: 04/01/2013 at 00:53
I agree, those are bracket fungi of some kind and will not affect any surrounding plants. Personally, I enjoy seeing fungi growing like that and find them fascinating. Apart from wood-boring beetle larvae, fungi are the primary way wood is naturally broken down and returned to the soil. The bracket fungi will eventually make the wood become very weak, so if any of the dead branches are above head height, I'd recommend you cut them off now in case they fall on someone. As LeadFarmer said though, it is always risky leaving dead tree stumps in the ground as they can become a base for a Honey Fungus infection, although I'm 100% certain that's not what you are seeing at this point.