When piled against the trunk, mulch cuts off necessary air circulation, causing inner bark (phloem ... diseased areas on the Yoshino cherry tree. Black knot, a disfiguring tumor-like fungus ...

The bark on young trees is smooth, but may be warty or feature some flaking. In old trees, the bark features prominent, light gray vertical flakes. Black willows, which grow 50 to 70 feet tall, prefer ...