Phytophthora Root Rot in Cedar: Diagnosis and Expert Referral

Phytophthora Species Root Rot: A Serious Cedar Pathogen

Phytophthora root rot affects many conifers, including cedars. The disease thrives in poorly drained soils and can kill trees of all ages.

Key Resources

• USDA Forest Service guide: Phytophthora root rot in cedars
• Trees forum expert Jim Hyland (former Forestry Service) for site-specific advice

Management Considerations

• Improve drainage—Phytophthora requires saturated soils
• Avoid replanting susceptible species in infected sites
• Fungicide treatments (phosphonates) may suppress but rarely eradicate
• Source healthy, disease-free nursery stock
• Remove and destroy severely infected trees

Professional Assessment Needed

With multiple trees affected and a "yard of weak trees" history, a certified arborist or plant pathologist should evaluate the site. Soil testing and root excavation may be necessary for definitive diagnosis and management planning.