Magnolia Trunk Cavity: Fill or Leave?

13-year-old magnolia has trunk hole with 2–3 ft standing water. Owner asks to drain, fill, or leave.

Modern Arboriculture: Leave It

• Filling creates differential expansion/contraction → new cracks.
• Strength comes from new wound wood, not fill.
• Drilling drain holes breaks decay barrier.

Options

• Best: Cover opening with screen/tin + plaster to exclude animals/rain, allow wound wood to roll.
• Acceptable: Suck water, dry, fill with expanding foam (if small).
• Also fine: Do nothing—tree compartmentalizes.

Boost Health

Fertilize 10-10-10 at 1 lb/inch trunk diameter annually.