Q: What is wrong with my magnolia tree? It is very large but some limbs are dying and the leaves are yellowing between the veins?

A: After exchanging some phone calls and looking at a few photos I didn’t feel any closer to determining what was wrong with the magnolia until I had branch specimens. My initial thought was something might be wrong at the root area.

We tested the soil pH and discovered it was alkaline near 7.3, but that didn’t completely explain why the tree was struggling. If the soil pH is too alkaline the root systems of plants cannot absorb some of the essential nutrients and it will often show up in the yellowing leaves. It is best not to add lime to Florida landscapes unless a soil analysis indicates it is needed.

Since 2-3 inches of organic mulch is all that trees or shrubs require, removal of the extra mulch was beneficial. Always keep mulch away from the trunk area of trees and shrubs. Avoid building “mulch volcanoes” as this can contribute to stem and root rot. Removal of competing lawn grass from the root area was also important.

However, part of the mystery was solved when I examined some of the magnolia limbs and discovered carpenter ants had bored into the vascular tissue of the limbs. Carpenter ants were also discovered at the base of the tree once the excess mulch was removed. One important thing to note is carpenter ants generally go into trees that are already in decline or stressed.

Will the tree recover? It might be worth trying, but all our efforts may not be able to bring the tree back to complete health. The dead limbs need to be removed immediately. If the root and lower trunk area indicated rot then it is time to think about taking the whole tree down.

0