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Etiology of Parsley Damping-off and Influence of Temperature on Disease Development. D. E. Hershman, Former Research Assistant, Department of Plant Pathology, New Jersey Agricultural Experiment Station, Rutgers University, New Brunswick 08903. E. H. Varney, Professor, and S. A. Johnston, Associate Extension Specialist, Department of Plant Pathology, New Jersey Agricultural Experiment Station, Rutgers University, New Brunswick 08903. Plant Dis. 70:927-930. Accepted for publication 23 April 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-927.

Damping-off of seedlings resulted in extensive stand reductions of parsley in southern New Jersey during the 19811982 growing seasons. The fungi most frequently isolated from field-grown seedlings with symptoms of postemergence damping-off were Fusarium oxysporum, F. solani, Pythium irregulare, P. ultimum, and Rhizoctonia solani (AG-4, AG-1, and AG-2, type 2). In pathogenicity tests, most isolates of P. irregulare and P. ultimum were highly pathogenic and caused extensive preemergence and postemergence damping-off. Similarly, most isolates of R. solani AG-4 and AG-2, type 2, were highly pathogenic. Isolates of AG-2, however, varied considerably in pathogenicity. No other fungi tested for pathogenicity incited disease in parsley. In sand bed studies, a combination of P. irregulare and P. ultimum isolates was highly pathogenic at 15, 23, and 30 C. R. solani, however, was much less pathogenic at 15 C than at either 23 or 30 C. A similar response was obtained in experiments in environmental chambers.