Leyland Cypress Top-Down Browning: Root Issues and Site Evaluation

Leyland cypress browning from the top down in Maryland typically indicates root system failure rather than foliar disease. When roots can't supply enough water to the crown, the highest foliage dies first. Causes include poor drainage, compacted soil, girdling roots, or root rot pathogens (Phytophthora).

The pattern spreading to adjacent trees suggests a site-wide issue—shared soil conditions or root graft transmission. Flat land with possible clay subsoil often creates perched water tables that rot roots over time.

A tree care company's visual inspection should include soil probing for drainage, root collar excavation to check for girdling roots, and possibly lab testing for Phytophthora. Treatment depends on diagnosis: drainage improvement, root collar exposure, or fungicide drenches.

Don't assume it's a foliar disease treatable with sprays. The real problem is underground.