By spring the needle spots are a yellowish brown to reddish brown. Sometimes spots coalesce to discolor the entire needle. The discolored needles are cast in the spring after spore discharge. Swiss Needlecast Foliage symptoms include yellowing and browning of needles in late fall of the first year or during spring and summer of second year. Symptoms are most severe on older needles on lower branches.
Diseased needles are often uniformly brown at the tips, but never mottled.
Needles infected by Swiss needlecast often turn brown at the tips in early spring. Trees with severe infection by P. gaumanni often have very few needles remaining prior to spring bud break. Spores Hyaline ascospores are released during wet weather and are wind disseminated. Needlecast 1-celled bone shaped 7x19 microns. Swiss Needlecast 2-celled spores 4x14 microns Ascospores of R. pseudotsugae are windblown and infect the young needles of opening buds.