Needle cast are fungal pathogens that affect a variety of plants but usually are identified in coniferous tree species like pine, spruce, fir and larch. There are various lifecycles involved but all these diseases result in premature needle drop (casting off).
Most needle cast diseases do not pose a threat to tree survival and while needle loss does stress the affected trees they are usually considered aesthetic problems.
Most needle cast diseases are aesthetic problems that usually attack second year or older growth. However, one disease, Lophodermium seditiosum, can result in tree mortality because it attacks new season growth and severely reduces photosynthetic ability. This more severe disease is not common in our region. The best control measure for this disease is to keep your trees healthy and well-watered, and to rake up and dispose of infected needles.