Conifers of many kinds can be affected by fungal infections during cool wet weather or if the plants are in too much shade. One of the most common diseases is Phomopsis Tip Blight. This plant disease is caused by the fungus Phomopsis juniperovora. The pathogen attacks the newest growth causing a tip blight (branches dying at the tip) or dieback of whole branches.

Symptoms appear during the growing season. Branch tips yellow and eventually turn a brown rusty color. If you look closely at the dead tissue you will see tiny black specks on the leaf tissue. This disease is most destructive during cool wet weather or if overhead irrigation is overused. Conifers in shade are susceptible as well.

There isn't much you can do besides trying to keep plants healthy through proper planting, fertility and watering, pruning out blighted branches and applying fungicide applications of general landscape fungicides according to labelled instructions.