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Ecology and Epidemiology

Influence of Temperature, Lesion Water Potential, and Cyclic Wet-Dry Periods on Sporulation of Cercospora arachidicola on Peanut. S. C. Alderman, Research associate, Department of Plant Pathology, North Carolina State University, Raleigh 27695-7616; M. K. Beute, Professor, Department of Plant Pathology, North Carolina State University, Raleigh 27695-7616. Phytopathology 77:960-963. Accepted for publication 22 December 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/Phyto-77-960.

Sporulation (conidia per millimeter of lesion area) of Cercospora arachidicola on peanut (Arachis hypogaea) leaflets incubated under 100% RH was greatest at 24 and 28 C, intermediate at 20 C, and least at 16 or 32 C. Sporulation decreased as the water potential of lesions decreased from 0.05 through 6.0 MPa. In cyclic wet/dry regimes of 24/0, 20/4, 16/8, 12/12, 8/16, 4/20, or 0/24 hr, in which the wet period was at saturation and dry period was at 75% RH, sporulation increased with increased wet period. Under well-watered conditions for plants, dawn or midday water potentials of lesions were significantly lower than adjacent healthy tissue. Diffusive resistance was higher and transpiration was lower for leaves with lesions than for those without lesions.

Additional keywords: Cercospora leaf spot, early leaf spot.