Crown and Root Rot
Phytophthora spp. (P
2 host plants
Last updated
This profile contains verified disease data from extension databases. Regional field notes and expert review are in progress.
Crown and root rot causes decay of roots and basal tissues leading to plant death. You see wilting and decline despite adequate moisture in soil. The fungus favors poorly drained soils and waterlogging. Improve soil drainage, avoid overwatering, and use well-draining media.
Root rots thrive in waterlogged soil, so drainage is your most important intervention. Avoid overwatering and ensure the planting site drains well. Remove severely affected plants to prevent spread to neighbors through root contact or contaminated soil. When replanting, choose resistant species or improve soil structure before putting anything back in the ground.
Quick Reference
Management
Most active during warm, wet periods in spring and early summer when soil is saturated or chronically moist. P. cinnamomi activity peaks at 65-85°F; P. cactorum more active at cooler temps (50-70°F). In the Puget Sound region, typically April-June and during wet fall conditions (September-November). # Source: PNW Plant Disease Management Handbook
Poor soil drainage; overwatering; heavy clay soils; warm soil temperatures (65-85°F optimal for P. cinnamomi); contaminated nursery stock; recycled irrigation water; root wounds. # Source: PNW Plant Disease Management Handbook - Crown and Root Rot
Cultural Controls
- Plant only disease-free, certified nursery stock. Inspect and discard any incoming plants with root rot, cankers, or discolored vascular tissue.
- Improve soil drainage by planting on raised beds or slopes. Amend heavy soils with compost or bark mulch to increase aeration.
- Plant at the same depth as the original nursery pot; do not plant too deeply, which promotes root collar infections.
- Avoid excessive irrigation and waterlogging. Water carefully at the soil line and avoid wetting the crown.
- Remove and destroy infected plants along with surrounding soil. Do not compost diseased material.
- Improve air circulation with proper plant spacing. Allow time for soil to dry between waterings.