Root and Crown Rot

Root and crown rot from Phytophthora cinnamomi attacks at soil level and spreads into roots and lower stems, causing sudden wilting, yellowing foliage, and plant collapse even though the canopy may look healthy. Affected roots and crown tissue become soft and discolored. The disease progresses rapidly in waterlogged soil and warm conditions, killing plants over weeks to months. You may notice the problem appearing in localized areas of the landscape where water collects or drainage is poor.

This soil-borne pathogen thrives in wet, poorly drained conditions common in Western Washington gardens after heavy rain. Excellent drainage is non-negotiable: ensure containers sit on gravel (4 inches or deeper) rather than directly on the ground, raise beds at least 15 inches, and break up compacted soil in planting areas. Avoid reusing pots or soil from previous crops without sterilization. Plant only certified disease-free nursery stock, and select resistant cultivars when available. Once established in a site, the pathogen is difficult to eliminate, so the priority is preventing it through cultural practices.