The pine needle cast fungus, Lophodermella concolor, caused severe discoloration and subsequent defoliation of lodgepole pine on over 4,000 acres and light defoliation on over 4,500 acres of lodgepole pine in the lower Clark Fork River drainage in 1975. Some trees had lost the last 3 years' growth of needles, undoubtedly due to L. concolor infection in those years. Mortality related to defoliation was not found. Damage occurred over a wide range of habitat types and was most commonly found in pole size stands heavily stocked with lodgepole pine.