I have an avocado tree that I have grown from seed (outdoors in a container) and lately it has been developing brown spots on the leaves, and I have noticed some spots on the branches of the tree also. This plant is very special to me. I planted 3 seeds close together and braided the plants as they grew. It is approximately 4' tall now and I would hate to lose it. I live in Houston, Texas and it gets only the morning sun and I water only when the soil feels dry and use Miracle Gro when I water. What am I doing wrong?