Database Research Summaries2018 Optimizing Row Spacing and Plant Populations for Management of Sclerotinia in Soybeans
Research Focus
The focus of this project is to develop rigorous, yield-maximizing row spacing and plant population recommendations for irrigated producers who suffer losses to Sclerotinia regularly and for dry land producers who observe losses to Sclerotinia sporadically.
Objectives
- Quantify the impact of row spacing on Sclerotinia disease levels, soybean yield, and soybean quality when seeding rate is held constant.
- Quantify the impact of low, intermediate, and high seeding rates (representing the full range of commonly employed seeding rates in North Dakota) on Sclerotinia disease levels, soybean yield, and soybean quality.
- Evaluate how the timing of Sclerotinia disease development influences the impact of row spacing and plant population on soybean performance and Sclerotinia disease levels.
- Evaluate whether soybean architecture type (upright vs. bush-type) influences the impact of row spacing and plant population on soybean performance under Sclerotinia pressure.
Results
- Field studies were established at the NDSU Carrington, Langdon, and Williston Research Extension Centers and at the NDSU Robert Titus Research Farm in Oakes. Fourteen soybean varieties representing a mix of upright and bushy types were evaluated in four-row spacing’s (7, 14, 21, and 28 inches or 7.5, 15, 22.5, and 30 inches) at each of three seeding rates (132,000; 165,000; and 198,000 pure live seeds/ac).
- Wide row spacing minimized Sclerotinia incidence but often did not optimize soybean yield. When Sclerotinia incidence was less than 50% in soybeans seeded to intermediate (21 or 22.5-inch) row spacing, yields were maximized with the intermediate row spacing. When Sclerotinia incidence in soybeans seeded to 21- or 22.5-inch row spacing was below 40%, the increased contamination of the grain with sclerotia (resting structures of the Sclerotinia fungus) associated with the narrower row spacing was never sufficient to result in a reduction in soybean market grade.
- Increasing the seeding rate from 132,000 to 198,000 pure live seeds/ac contributed to a modest increase in Sclerotinia disease pressure but also a modest increase in soybean yield.
- The results suggest that if Sclerotinia incidence is not expected to exceed 40 to 50 percent, seeding soybeans to 14 to 22.5 inches is likely to maximize soybean yield under white mold pressure without reductions in soybean market grade.
Importance
This research will develop rigorous, yield maximizing row spacing and plant population recommendations for irrigated soybean producers who suffer losses to Sclerotinia regularly and for dryland producers who observe losses to Sclerotinia sporadically.
For more information about this research project, please visit the National Soybean Checkoff Research Database.
Funded in part by the soybean checkoff.
