Hi, i have two little avocado trees. The first is almost completely dead, all leaves were coming off over a few months. I repotted it, the roots look almost completely rotten. It's that short because I pruned it before it lost all it's leaves. The second looks ok, but i don't want to risk it losing it too. Any ideas what i can do? I have a layer of vermiculite in the bottom of the pots to provide better drainage, the soil is a mixture of commercial potting soil and vermiculite. I spray a lot and water seldomly.