Efficacy of Fungicides Against Persistence of Alternaria dauci on Carrot Seed. J. O. Strandberg, University of Florida, Institute of Food and Agricultural Sciences, Agricultural Research and Education Center, Sanford 32771. Plant Dis. 68:39-42. Accepted for publication 20 July 1983. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-39.

Fungicide soaks or seed dressings did not completely eradicate Alternaria dauci from a naturally infested lot of carrot (Daucus carota) seed. Some treatments appeared effective when small numbers (100) of treated seeds were assayed. A. dauci could not be found on treated seeds tested by a simulated seed-germination blotter method or seedling assay. Larger seed samples tested in field isolation plots or in a controlled-environment seedling assay showed that A. dauci was not eradicated from all seeds. The most effective fungicides, thiram and iprodione, applied as a 24-hr soak, allowed A. dauci to persist on 0.4 and 0.01% of the treated seeds, respectively. The effectiveness of the iprodione soak was dependent on fungicide concentration, temperature, and treatment duration.

Keyword(s): seedborne fungi.