The effect of fungicide seed protectants, seeding rates, and reduced rates of herbicides on no-till soybean

A field study was conducted to determine if fungicide seed protectants, reduced rates of a complete preemergence or a complete postemergence herbicide program, and soybean seeding rates affect weed control and yield in a no-till system. Asgrow 3237, Pioneer 9273, and Pioneer 9342 soybean cultivars were planted into corn stubble at Urbana, Illinois in 1995 and 1996. Fungicide seed protectants increased soybean population density and reduced time to canopy closure in 1995, but had no effect in 1996. As seeding rates increased from 34.6 to 54.3 seeds m ^-2, yields increased, and time to row canopy closure was decreased. In general, adequate weed control and soybean yields were maintained using reduced rates (≥0.5X) of herbicides. In 1996, the purple seed stain fungus, Cercospora kikuchii, was isolated more often from Pioneer 9273 seed and Asgrow 3237 seed harvested from the no-herbicide, weedy control plots compared to plots treated with herbicides.