Effects of Tillage, Cultivar, and Planting Date on Percentage of Soybean Leaves with Symptoms of Sudden Death Syndrome. J. A. Wrather, University of Missouri-Delta Center, P.O. Box 160, Portageville 63873 . S. R. Kendig, and S. C. Anand, University of Missouri-Delta Center, P.O. Box 160, Portageville 63873; and T. L. Niblack and G. S. Smith, University of Missouri-Columbia, 108 Waters Hall, Columbia 65211. Plant Dis. 79:560-562. Accepted for publication 16 March 1995. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/PD-79-0560.

A 4-year experiment, 1991 to 1994, was conducted in a field where sudden death syndrome (SDS) had previously been observed. The objective was to determine the effects of tillage, planting date, and soybean cultivar on the percentage of leaves with symptoms of SDS at R6 growth stage. The soybean cultivars Essex, Forrest, Hartwig, and Rhodes were each planted in 75-cm-wide rows in disk-till, ridge-till, and no-till plots. The planting dates were mid-May, mid-June, and late June to early July each year. Symptoms of SDS developed in 1991, 1992, and 1994, but in not 1993. There were significant year x cultivar (P = 0.0001) and tillage x planting date x cultivar (P = 0.05) interactions for the percentage of leaves with symptoms of SDS. Essex, Forrest, and Rhodes had a greater percentage of leaves with symptoms of SDS than did Hartwig in 1991 and 1994; differences among cultivars did not occur in 1992. The percentage of Essex, Forrest, and Rhodes leaves with symptoms of SDS was greater for no-till than for either disk-till or ridge-till in mid-May plantings. There were no significant correlations between the percentage of leaves with SDS and yield.

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