Overview
Needlecast diseases are caused by several fungal pathogens that infect conifer needles, causing discoloration and premature needle drop. Rhizosphaera and Stigmina are the most common needlecast diseases affecting spruce in Colorado.
Signs & Symptoms
- Purple or brown discoloration of older needles
- Premature needle drop, usually retaining current year's growth
- Thinning appearance, especially on lower branches
- Black fungal fruiting bodies visible on needles
- Progressive defoliation over several years
Treatment
Fungicide applications in spring can protect new growth. Multiple years of treatment are often necessary. Improving air circulation, avoiding overhead watering, and maintaining tree health are important management practices.