Question
Hey Tom, We have a group of Magnolia Trees behind our pool. Two of the three started to lose leaves about 3-4 months ago (we live in the Dallas-Fort Worth Area. The trees are about 4 years old and have been doing quite well up to this point). We called in an Arborist who believed the issue was salt run-off from the pool. We believe the issue is over watering, from some new plantings nearby. Either way what is the best approach and fertilizer to use to help bring back these trees?

Answer
Hi Steve,
Thanx for your question.  I agree with the arborist.  I think the chemicals from the pool stressed the tree.  Rainfall will leach the chemicals out of the soil.  Use a fertilizer like 10-20-10 which has the higher number (middle-Phosphorus-for flowering trees).  Jobes and Bachman are two brands that come to mind although I am not endorsing either, just giving ideas. Apply fertilizer in the fall and spring.  The bottom line is to keep the run-off from the pool from reaching the tree roots.  Remember that the roots extend out past the drip line of the trees (where the rain waters drip from the farthes branches.  Eventually, (it doesn't take long) the natural rainfall will leach the salts out of the soil.  I hope this helps.
Tom