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Disease Note

Damping-off of Portulaca Caused by Helminthosporium (Bipolaris) portulacae in North Carolina. D. L. Strider, North Carolina State University, Raleigh 27695-7616. Plant Disease 68:826, 1984. Tran Thi Le Chi, North Carolina State University, Raleigh 27695-7616. Plant Dis. 68:826. Accepted for publication 11 June 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-826c.

Helminthosporium (Bipolaris) poriulacae Rader was isolated from dead and dying portulaca (rose-moss, Poriulaca grandiflora Hook) seedlings. Seeds soaked in 0.5% sodium hypochlorite for 10 min before planting remained healthy, suggesting external seed contamination of the pathogen. inoculation of sodium hypochlorite-disinfested seed or of seedlings with a spore suspension (5 X 10' spores/ml) of H. (Bipolaris) portulacae resulted in about 90%damping-off. Near 100%damping-off occurred when the common weed purslane (P. oleracea L.) was seeded into soil infested with H. (Bipolaris) portulacae, suggesting a possible biological control of purslane. The pathogen has previously been reported to cause leaf spot of purslane, but this is the first report of the pathogen causing disease of the bedding plant portulaca.
Reference: Rader, W. E. Mycologia 40:342, 1948