By Robert Battel
How do soybean seed treatments perform on late-planted soybeans?
The purpose of this study was to determine if soybean seed treated with an insecticide plus fungicides, CruiserMaxx plus Vibrance, had an effect on soybean emergence and yield. This study was conducted on two sites in Michigan, one near Avoca in St. Clair County and one near Port Sanilac in Sanilac County. The Avoca site was planted May 24 and the Port Sanilac site was planted May 31.
Michigan State University Extension’s Thumb Ag Research and Education personnel planted soybeans in 75-foot long by 15-foot wide plots. Plots were planted perpendicular to the field tile. Plots were established in a randomized complete block design. The treatments at all sites were replicated four times. At both sites, the soybeans were planted in 30-inch rows with a target planting rate of 130,000 seeds per acre.
The variety used in this study was NK S20-16 Brand and all seed planted in the trials, treated and untreated, came from the same seed lot. Results of both seed emergence and soybean yield are presented in the tables below.
Seed treatment effect on soybean emergence |
|---|
| St. Clair | Sanilac | Average |
|---|
Plants/A | Plants/A | Plant/A |
|---|
Treated | 110,000 | 119,000 | 114,500 |
Untreated | 115,000 | 122,500 | 118,750 |
Seed treatment effect on soybean yield |
|---|
| St. Clair | Sanilac | Average |
|---|
Yield (bu/A) | Yield (bu/A) | Yield (bu/A) |
|---|
Treated | 46.0 | 54.4 | 50.2 |
Untreated | 45.4 | 54.5 | 50.0 |
CV (%) | 8.0 | 5.0 | — |
LSD (bu/A) | NS | NS | NS |
Emergence scores were taken about one month after planting. Even though statistics were not run on the emergence results, the treatment appears to have had no effect on soybean emergence at the two locations. The differences in yield between treated and untreated seed at the two locations were also not statistically significant.
As noted in the introduction, these soybeans were planted within normal planting times, but later in the season after soils had warmed. Insecticide and fungicide seed treatments are expected to be more beneficial when soybeans are planted in cooler, wetter soils. Cool soils delay germination and emergence, allowing more time for insects and plant pathogens to attack the seed and seedlings and wet soils favor development of soybean diseases such as pythium, phytophthora and phomopsis.
The Michigan Soybean Promotion Committee provided funding, as well as seed to make this study possible.