S2White pine blister rust (Cronartium ribicola, Fischer) is a virulent and potentially serious disease of eastern white pine (Pinus strobus, L.) Control of this introduced rust has been carried on since about 1910 in the eastern United States. Today, after more than 50 years of control effort, the occurrence of blister rust in this region is gratifyingly infrequent. Because of effective and continuing control programs, blister rust has been brought under control, and is not now a serious threat to pine management in most areas of the East. Yet, control must continue if blister rust is to remain under control in the future.S3.