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Disease Note Leaf Spot of Marigold Caused by Seed Contaminated with Pseudomonas syringae pv. tagetis in North Carolina. D. L. Strider, Department of Plant Pathology, North Carolina State University, Raleigh 27695-761 6. Plant Dis. 68:1016. Accepted for publication 17 August 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-1016d. Bacterial leaf spot of marigold (Tagetes erecra L.). incited by Pseudornonassyringae pv, targetis, Young, Dye. & Wilkie, was severe on cultivars Lemondrop. Petite Spray, and Petite Yellow in greenhouses in North Carolina during 1983 and 1984. Koch's postulates were successfully completed. Less than 1% of Lemondrop seedlings from a lot of naturally infested seed showed initial symptoms on cotyledons, but spread from these seedlings was rapid, and the lot yielded only 21.5% marketable bedding plants. A 30-min seed soak in 0.5% sodium hypochlorite did not reduce germinability of Lemondrop, Petite Spry. or Petite Yellow. Sufficient naturally infested Lemondrop seed for efficacy studies were unavailable. For marigold to remain a popular bedding plant seedsmen must recognize the pathogen's destructive potential and rogue seed fields to produce pathogen-free seed. |