See:
Spruce (Picea spp.) - Tip Blight
Cedar (Cedrus spp.) - Needle Blight
Cause Sirococcus conigenus, a fungal disease found more often in nurseries and forests than in the landscape. Spores are spread by splashing water and by infected seeds. The fungus infects several pine species, blue and sitka spruces, and western hemlock.
Symptoms Needles on new shoots may turn brown and drop, and infected twigs die back to the main branch. If the shoot was actively growing when it was killed it may have a crook-shape bend. A small purple lesion with a resin drop may be found at the infection site (near needle bases on new shoots). Small black fungal structures (pycnidia) can be found on the infected twig about a year after the initial infection. May be confused with frost or herbicide damage.
Cultural control
- Avoid overhead watering, both to reduce humidity and to reduce spread of disease by splashing water.
- Destroy any seedling trees that show signs of infection.
- Do not plant susceptible trees in shady areas; low light favors disease development.
- Prune and destroy infected branches where practical.
- Space plantings to provide good air circulation.
Chemical control Use at two-week intervals starting when new shoots are breaking bud and expanding.
- Armada 50 WDG at 3 to 9 oz/100 gal water. Do not use a silicone-based surfactant. Not for nursery or greenhouse use. Group 3 + 11 fungicide. 12-hr reentry.
- Bravo Weather Stik at 2 to 3.5 pints/A. Group M5 fungicide. 12-hr reentry.
- Concert at 69 fl oz/100 gal water. Landscape use only. Group 3 + M5 fungicide. 12-hr reentry.
- Echo 720 at 2 to 3.5 pints/A. Group M5 fungicide. 12-hr reentry.
- Heritage at 1 to 4 oz/100 gal water plus a non-silicone-based wetter sticker. Registered for conifers including Christmas trees. Group 11 fungicide. 4-hr reentry.
- Mural at 4 to 7 oz/100 gal water. Registered for ornamentals grown in nursery, greenhouse and landscapes. Group 7 + 11 fungicide. 12-hr reentry.
- ProCon-Z at 16 oz/100 gal water. Registered for use in field nurseries and landscapes. Group 3 fungicide. 24-hr reentry.
- Spectro 90 WDG at 1 to 2 lb/100 gal water. Registered for conifers grown in nursery, greenhouse or landscape. Group 1 + M5 fungicide. 12-hr reentry.
Reference Sinclair, W.A. and Lyon, H.H. 2005. Diseases of Trees and Shrubs. Second Edition. Ithaca, NY: Cornell University Press.