There are two Douglas-fir trees visible behind the speaker. The tree on the right is partially defoliated by Rhabdocline needle cast, while that on the left retains most of its needles. In plantings of trees raised from seed, differences between some individuals probably reflect real genetic characters. B.C.D. Needle Rust of Spruce and Pine. These may be white, orange or yellow.
Rusts are the subject of an entire section of their own.
D. Pine needle rust caused by Coleosporium. Foliage Symptoms which may resemble Needle Blight. When needles on a few branches turn brown while foliage on the rest of the tree seems normal, a branch canker should be suspected. E. Cytospora Branch Canker of Spruce. F. Seridium Blight of Cypress.