Disease Note

First Report of Erwinia carotovora var. carotovora Stem Canker and Wilt of Zucchini Squash. R. M. Sonoda, University of Florida Institute of Food and Agricultural Sciences, Agricultural Research Center, Ft. Pierce 33454-0248. R. G. Rohde, University of Florida Institute of Food and Agricultural Sciences, Agricultural Research Center, Ft. Pierce 33454-0248. Plant Dis. 69:613. Accepted for publication 20 February 1985. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/PD-69-613a.

Stem cankers and wilted plants of zucchini squash (Cucurbita pepo var. melopepo (L.) Alef.) were observed in several plantings on the same farm in Delray Beach, Florida, during 1983–1984. In a 2-ha planting surveyed in November 1983, 80% of the plants had stem cankers, some so severe the plants wilted and died. Stem cankers were usually observed just before the first harvest. Infection occurred at wounds resulting from separation of petiole from stem. Erwinia carotovora var. carotovora (Jones) Dye (Ecc) was consistently isolated from lesions with bacterial ooze. The isolates caused soft rot of potato, had negative phosphatase test reactions, were resistant to 15 μg/ml of erythromycin, and reacted similarly to a known Ecc in other biochemical tests. Koch’s postulates were confirmed. Seedlings of 30 zucchini squash cultivars obtained from several commercial seed companies were killed when wound-inoculated at the first true leaf stage with two isolates of Ecc from squash.