Establishment of Alternaria Leaf Blight on Carrots in Controlled Environments. J. O. Strandberg, Professor and Plant Pathologist, University of Florida, Institute of Food and Agricultural Sciences, Central Florida Research and Education Center, Sanford 32771. . Plant Dis. 72:522-526. Accepted for publication 21 January 1988. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/PD-72-0522.

Carrot plants in the 4- to 6-leaf stage were sprayed with conidia of Alternaria dauci. Incubation at 16–28 C in 100% relative humidity with wetted leaves for 24 hr was required for infection. Temperatures above 12 C during night hours along with wetted leaves were necessary for disease development. Responses of plants to disease development were evaluated with a damage index key that estimated the percent of leaf area damaged. Intermittent misting of plants during night hours made disease development in a greenhouse possible. Surfactants improved the efficiency of collection of conidia produced in culture and their application to plants.

Keyword(s): Daucus carota, inoculation, leaf wetness.