Effect of fungicide seed treatment and seed quality on soybean stand and yield in Arkansas

The efficiency of ten fungicide seed treatments was determined on high and low quality seed lots of the soybean cultivar Pioneer 94M90 at three locations in Arkansas, planted in April, May and June. The treatments included five selective fungicides and five broad-spectrum fungicides (some included insecticides). Significant increases in stand occurred across location and planting dates with the broad-spectrum seed treatments. Metalaxyl (Allegiance) was the least effective seed treatment of the selective fungicides indicating a limited role of Pythium spp. in seedling diseases. Low quality seed reduced stands. However, Stilletto (carboxin-thiram-metalaxyl) significantly improved the stand and yield of low quality seeds. Yields generally reflected stand within a planting date. Yields significantly declined with delays in planting. Seed treatments showed better stand improvement in the May and June than in the April planting dates.