MSU Extension

Soybean planting has been delayed by the frequent and heavy rain events occurring this spring, so many soybean fields will be planted in June. Producers need to implement specific management practices to maximize the yield potential of late-planted soybeans. These practices are summarized below.

Planting date

Plant as early as soil conditions permit. Yield losses due to delayed planting increase from 0.4 bushel per acre per day on June 1 to 1.0 bushel per acre per day on July 1. Also, remember that soybean maturity is delayed by one day for every three days that planting is delayed, increasing your risk of frost or freeze injury in the fall.

Soybean variety maturity

Planting the correct maturity group is critical to maximizing soybean yields when planting in June. Most university trials have shown that adapted full-season varieties will yield better than earlier maturing varieties when planted in June as they produce a larger crop canopy before beginning to flower. However, planting full-season varieties too late in the season increases the potential for frost or freeze damage to occur in the fall. Planting early-maturing varieties too soon will result in lower yield potential and short plants. The lowest pods on these short plants will be below the sickle bar on the grain table and left in the field at harvest. Consider planting earlier varieties after June 20. However, avoid planting varieties that are more than 0.7 of a maturity group earlier than adapted full-season varieties for your area when planting late.

Row spacing and planting population

When planting in June, plant in narrow rows of 15 inches or less and increase planting populations. The combination of narrow rows and higher populations will help the crop canopy cover the soil sooner and capture more of the available sunlight. These conditions produce higher yields by reducing evaporation and increasing photosynthesis. When planting with a drill, increase planting populations to 200,000 to 225,000 seeds per acre when planting during the first half of June, and to 225,000 to 250,000 seeds per acre when planting in late June. Higher plant populations will help compensate for the shorter plants and fewer nodes per plant that are common in late-planted soybeans.

Seed treatments

Fungicide and insecticide seed treatments are less beneficial with late planting as the soil will be warm and germination and emergence should occur rapidly (six to seven days). If you are planting into a field with a history of Phytophthora root rot, and the variety does not possess specific race resistance, treat the seed with Mefanoxam at 0.64 fl oz per cwt.

Planting depth

Plant into uniform moisture if possible, but don’t plant over 1.5 inches deep or less than 1 inch deep with a drill. Depth control is less precise and consistent when planting with a drill and you don’t want to risk leaving beans on the surface or placing them too deep.

Soybean aphid management

Aphids deposited into soybean fields in the vegetative stages during mid-season flights will reproduce more rapidly and reach economic thresholds two weeks sooner than aphids deposited into fields in the early reproductive stages. Scout less mature fields often and thoroughly. Late-planted soybeans are also more susceptible to injury from aphid feeding as they will have less leaf area and root growth than soybeans planted earlier in the season.

Harvest and storage

If late-planted soybeans are damaged by frost in the fall, some of the beans will be green and immature at harvest. To avoid or reduce elevator discounts, screen out the small beans, dry the rest to 12 percent and store them in aerated bins for at least four to six weeks. The green color will fade after this amount of time.

Crop insurance decisions

Producers that have purchased federal crop insurance have prevented planting coverage. Contact your insurance agent to find out the “final planting date” and the “late planting period” for soybeans in your county or counties. The late planting period is the 25 days following the final planting date. Make sure you understand the rules and ramifications of the following options. These are explained further in a USDA-RMA Program Announcement Prevented Planting Examples-Soybeans.

Take the prevented planting payment after the final planting date has passed and do not plant another crop for the year. Plant soybeans after the final planting date, but before the end of the late planting period. The production guarantee or amount of insurance will be reduced by 1 percent for each day that planting is delayed past the final planting date. Take the reduced prevented planting payment on soybeans and plant another crop any time after the late planting period for soybeans has passed.

This article was produced by the SMaRT project (Soybean Management and Research Technology). The SMaRT project was developed to help Michigan producers increase soybean yields and farm profitability. Funding for the SMaRT project is provided by MSU Extension and the Michigan Soybean Checkoff program.