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Resistance to Corynebacterium michiganense Measured in Six Lycopersicon Accessions. B. D. Thyr, Pathologist, Plant Science Research Division, ARS, USDA, Cheyenne Horticultural Field Station, Cheyenne, Wyoming 82001; Phytopathology 61:972-974. Accepted for publication 15 March 1971. DOI: 10.1094/Phyto-61-972.

Resistance to bacterial canker of tomato (Corynebacterium michiganense) was measured in four accessions of Lycopersicon esculentum, one of L. pimpinellifolium, and one of L. hirsutum. The measure of resistance was based on canker length, percentage of the stem with internal vascular discoloration, and by the number of pathogen cells per gram of stem tissue (fresh weight). Canker length correlated statistically with percentage internal discoloration, but not sufficiently to justify its use as an independent measure of resistance. Percentage internal discoloration and cells per gram of fresh tissue had an obvious positive correlation. Data tend to support the hypothesis that resistance is at least partially a matter of bacterial inhibition.