White spruce are somewhat susceptible. Norway spruce are relatively resistant. Rhizosphaera Space trees and provide good weed control to insure free air circulation around the tree. Some locations have an additional infection period in September and October. Needle Rust Year-old needles are cast after turning rust colored in the spring.
Blue spruce is very susceptible.
Black, Engelmann, red, Sitka, and white spruces are also susceptible. This rust does not require an alternate host. Chrysomyxa weirii Notify the Bureau of Plant Industry immediately to obtain a positive diagnosis Destroy infected trees.