Infection and Colonization of Inflorescences and Mericarps of Carrot by Alternaria dauci. J. O. Strandberg, Professor and Plant Pathologist, University of Florida, Agricultural Research and Education Center, Sanford 32771. Plant Dis. 67:1351-1353. Accepted for publication 16 June 1983. Copyright 1983 American Phytopathological Society. DOI: 10.1094/PD-67-1351.

A 0.25-ha field of carrots (Daucus carota) infested with Alternaria dauci was managed as an experimental seed production field. Extensive leaf blight in the field caused by A. dauci enhanced the probability of attack of flowers and fruit. Components of the carrot inflorescence were examined at intervals for infection by A. dauci; all were susceptible. Fruits (mericarps) were vulnerable to infection from early development to maturity. Mericarps infected early in their development contained seed structures completely colonized by the fungus. Tissues and spiny prickles of the vallecular ridges of fully developed mericarps were the most common sites of infection, colonization, and sporulation by A. dauci. The fungus was confined to the outer surface and tissues of dried pericarps and did not penetrate the seed coat and endosperm.