Diplodia Tip Blight in Norway Spruce Plantations

Symptoms

Brown, curled new growth (candles) that are woody and don’t break easily, with black fruiting bodies under needle sheaths, indicate Diplodia tip blight (not insect borers).

Control

1. Maintain vigor: water during drought, fertilize, control insects.
2. Prune infected tips in dry weather; sterilize tools.
3. Apply protective fungicides (Bordeaux mix, thiophanate-methyl) at bud break and repeat as new growth expands.

Timing is critical—sprays only work during the infection period in spring.