• leave and bud growth,
• leaf size,
• twig growth, and
• signs of crown dieback (the gradual death of the upper part of the tree).

Of course, mature trees respond well to responsible mulching, but require a wider mulch blanket, extending to the borders of their root systems. Ideally, the mulching area for a mature tree is two to three times the diameter of its branch spread. In central Florida, where wide radial tree shapes (spreading horizontally as opposed to vertically) are common, this may not be possible (imagine two to three times the spread of a mature live oak). In this case, a mulch blanket extending to the drip line is recommended.

Urban trees submit to conditions that challenge their nutritional balance, such as traffic congestion, higher temperatures, soil compaction, pollution and ozone. Before using any supplemental fertilizer, it is important to know what nutrients are needed and surrounding soil characteristics (such as Ph and organic matter content). Also make certain that when you use fertilizers and pesticides for other purposes, you may inadvertently be applying them to the wide-reaching root system of nearby mature trees.

Naturally, tree removal is a final resort, for trees that are dead, dying or irreparably dangerous, when a tree may present an obstruction or other risk.