Maple Tree Decline from Dry Rot: Borer Damage and Fertilization Strategy

How Dry Rot Starts

Decay fungi enter through bark wounds. Maples have thin bark; borer insects create entry points. The fungi decay the dead heartwood, weakening the trunk over years.

Two-Pronged Approach

1. Fertilize: 10-10-10 at 1 lb per inch of trunk diameter, spread to dripline, water in. Repeat spring and summer.
2. Treat Borers: Spray Merit (imidacloprid) or similar into wounds and on trunk. Check local nursery.

Cavity Care

Do not fill with concrete. Expanding foam can seal out water. The living cambium is just under the bark; the dead center can rot slowly without killing the tree if the outer layers stay healthy.