Since SDS was first reported in Iowa in 1994, soybean growers and agronomists who have experience with this disease have observed that it seems more severe in early planted soybean. Surveys completed by participants of extension winter meetings in Iowa also indicated that fields showing severe defoliation in the fall are likely to have been planted before May. Last year's warm spring and early planting may have contributed to the high prevalence of SDS in the 2002 growing season. Rarely, there are cases of severe SDS in fields planted after May 15. Research in Missouri confirms that the disease is more severe in fields planted in early spring.
Iowa State University
Yang, X. B. and Navi, Shrishail S., "New insights on early planting and SDS" (2003). Integrated Crop Management News. 1679.
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