Plum rusty blotch, a graft-transmissible disease of Japanese-type plums, has been observed on several commercial varieties throughout the plum-growing areas of California. During 1960 trees showing symptoms of plum rusty blotch were found in Fresno, Kern, Madera, Merced, Placer, Riverside, San Bernardino, San Joaquin, Santa Clara, Santa Cruz, Solano, Stanislaus Sutter, Tulare, and Yuba counties. The disease has been noted on the varieties Elephant Heart, Howard's Miracle, Kelsey, Laroda, Late Santa Rosa, Redroy, and Santa Rosa. The transmitting agent is not known.

The above report is based on cooperative investigations of Crops Research Division, Agricultural Research Service, USDA, and University of California Experiment Station, Riverside, and is part of Research Project No. 1002.