What causes "Florida Pine Decline" or "Golden Pine Syndrome"?

Answer: Experts agree that the problem is caused by the use of high pH irrigation water containing large amounts of free calcium. Calcium has an antagonistic reaction within plants towards iron, manganese, and zinc, preventing those elements from helping produce chlorophyll. While none of those elements are present in the chlorophyll molecule, they are absolutely essential for the production of this energy producing element. Without chlorophyll plants must live off stored energy reserves, which accounts for the slow but steady decline of affected trees. The plants simply cannot produce needed food to sustain themselves and gradually decline and die or are killed by insects or disease attracted to their weakened state. Emerald Tree can effectively supply the needed sulfur, iron, zinc, and manganese to enable the trees to begin to produce chlorophyll and replace lost energy reserves. Color will begin to darken very rapidly and should reach normal within six months.

Trees and Turf does this all the time and has saved golf-courses hundreds of thousands of dollars treating trees, rather than replacing them.