Problem with new pear tree and new cherry trees

[The Happy Walnut]

Hello,

I planted a new pear tree in my backyard about a month ago, and I think it is dying. It never flowered and now it seems to have black spots on most of the leaves now and they're drooping.

As for my two new cherry trees, I also planted them about a month ago, and they were doing fine. Each one produced about six cherries. However, I noticed this past weekend that some of the leaves on both trees have turned yellow and are falling off. And the leaves aren't as perky as they used to be.

This is my first time planting fruit trees and I'm not quite aure what is wrong with them. Any suggestions?