January 12, 2012

A seed treatment trial was conducted at four locations in Nebraska in 2011 to determine its effect on stand, disease control, and yield. The sites, part of the Soybean Management Field Days, were near Bancroft (northeast Nebraska), Clay Center (south central), Cortland (southeast), and Elba (central).

Researchers found that seed treatments did not cause any yield differences at any of the sites. There were differences in stand counts at Clay Center and Elba in the spring, and at Clay Center in the fall; however these differences did not influence yield.

How the Trial was Conducted

The study included 10 treatments and an untreated control.

• Plot size: 4 rows wide by 17 feet long.
• Planting: 140,000 seeds/ac at a depth of 2.5 inches to promote disease development. Syngenta NK S25-T8 soybean seed was used for all sites.
• Weed control: Warrant (acetochlor) and Round up (glyphosate).
• Treatments were arranged in a randomized complete block design and were replicated four times at each site.

Seed treatments were applied using a slurry sufficient for 2 lb of seed for each treatment. Uniform coverage to the seed was accomplished in a resealable plastic bag. Stand counts were taken twice in the spring and once in the fall prior to harvest. Plant populations were determined by counting plants between two flags placed 10 ft apart in the center two rows of each plot. The stand count flags remained in place for the entire season so that the same area was counted at each stand count assessment. Stand count data was converted into plants per acre. Prior to harvest, the ends of each plot were cut to minimize edge effects on yield. All yields were adjusted to 13% moisture. Additional site details are given in the table headers below.

Findings

Weather conditions from planting until mid-June were cool and wet across much of the state. These conditions combined with deep seed placement resulted in slow and uneven emergence. In some cases soybeans were still emerging 21 to 35 days after planting (DAP).

Seed treatments did not cause any yield differences at any of the sites. There were differences in stand counts at Clay Center and Elba in the spring.. In the fall, Clay Center had differences in stand counts but none of the treatments were different from the untreated control. These differences did not influence yield.

Loren Giesler
Extension Plant Pathologist, Lincoln
Travis Gustafson
Technologist, Department of Agronomy and Horticulture