Needle Cast, Rhabdocline

Douglas-fir needles show yellow spots developing to deep red-brown mottled areas by spring, with orange fungal structures visible on the underside; needles drop by June. Rhabdocline fungi favor cool, moist spring conditions. Avoid low-lying sites with poor drainage, space for air flow, and avoid east-side seed sources that are highly susceptible.

Avoid planting in low-lying areas with poor air drainage. Space plants for good air circulation. Remove infected material promptly and improve growing conditions to limit pathogen spread. Good sanitation, adequate spacing, and proper irrigation practices reduce disease pressure over time.