Common Cedar Tree Diseases: Rust, Phytophthora, and Root Rot

Overview

Cedars are low‑maintenance evergreens but host several damaging diseases. Early recognition preserves tree health.

Cedar‑Apple Rust

Fungus alternates between cedar and apple/crabapple. On cedar: woody galls on twigs. Causes brown foliage, distortion, secondary infections. Remove galls by hand (gloves); spray fungicide to break cycle.

Phytophthora Root Disease

First reported Seattle 1923. Symptoms: water‑soaked appearance, dark stained wood, pale foliage, drying inner bark. Beetles attack weakened trees. Requires pesticide treatment or removal to prevent spread.

Root Rot (General)

Wilting, browning leaves despite adequate water. Sometimes salvageable by removing affected roots, improving drainage, and nitrogen fertilization. Usually fatal; remove tree to protect neighbors.

Prevention

• Plant in well‑drained sites.
• Avoid overhead irrigation.
• Space for airflow.
• Monitor regularly for early signs.