Phomopsis Canker of Russian-Olive in Southeastern Michigan. H. M. Maffei, Graduate Student, Forest Resources Program, School of Natural Resources, University of Michigan, Ann Arbor 48109. H. L. Morton, Professor, Forest Resources Program, School of Natural Resources, University of Michigan, Ann Arbor 48109. Plant Dis. 67:964-965. Accepted for publication 28 February 1983. Copyright 1983 American Phytopathological Society. DOI: 10.1094/PD-67-964.

Phomopsis elaeagni caused 52 of 53 cankers found on a sample of 100 Russian-olives located throughout southeastern Michigan. Fifteen randomly chosen isolates all caused typical disease symptoms and were subsequently reisolated. Host colonization rates varied among the isolates in a field experiment, and isolates varied similarly when retested in the greenhouse. Seedlings were least susceptible to an aggressive isolate when inoculated at budbreak. P. elaeagni extended less than 15 cm below the canker in 23 of 24 infected branches.