White pine blister rust is widespread and abundant on sugar pine in northwest California. In the central Sierra Nevada, it tends to occur in "pockets" in canyons and stream basins. Records of infection near the southerly limit of the disease were scrutinized. Data from 14 areas were studied statistically. Eight physiographic factors were computed for each rust center. Canyon physiography and intensity of rust were markedly correlated. A records approach to prediction of future rust incidence in the central Sierra Nevada could be useful in planning control work.