Last year I had 2 dwarf Granny Smith apple trees planted. One was doing well, but the other looked like it was dying. The person planting them said the sick one could be under stress and to water and feed it more. This I have been doing. Now it has a white fuzzy stuff on the trunk and branches that looks like mealy bugs. I've attached a picture. What could this be and how should it be treated? The tree still shows very poor grow, but the other tree near it is doing great.