Early season soybean replant decisions
The final decision on whether to replant should also include the costs incurred from a replanted or existing stand. Some factors to consider include costs of replanting (i.e., seed, labor and fuel) and crop insurance. Other management decisions may be made to ensure yield potential of either replanted or existing stands.
Pesiticides. Depending on the timing and type of product applied, herbicide residual could prevent soybean replanting. However, an existing stand will likely require additional post-emergence herbicide application(s) due to the delayed or lack of canopy closure. Read herbicide labels to determine any possible replant considerations from herbicide applications already made.
Injured soybean has a higher risk of disease infection due to slowed growth and bruising. Depending on the type and severity of injury, there may be increased risk potential for late-season lodging, Phomopsis seed decay and brown spot or other foliar diseases. Disease prevalence is highly dependent on stage of growth at the time of injury and weather conditions during the remainder of the growing season. However, keeping an existing, reduced stand would lower the risk of white mold occurrence.
Replanted soybean does not generally benefit from insecticidal and fungicidal seed treatments due to warmer soils that provide quick emergence and growth. However, fungicidal seed treatments may still be beneficial because some pathogens prefer warmer and drier soil conditions for infection. Fungicide seed treatments should be used in field areas that are prone to seedling diseases. Replanting later in the season may reduce the risk of sudden death syndrome and could also reduce the risk of white mold because of delayed canopy closure.
Maturity selection, seeding rates and row spacing. Many of the cultural recommendations that are made for late-planted soybean can be followed for replanting of soybean. Selecting seed for replanting is largely based on the seed available. Seed quality should be considered in addition to yield stability, herbicide traits, soybean cyst nematode resistance and other variety characteristics that are normally considered. If possible select varieties that have bushy foliage characteristics and 0.5 to 1.0 maturity groups lower than normal due to later date of planting.
Soybean planted in late May and June should be planted at a seeding rate of 135,000 to 160,000 seeds per acre (or 10 to 15 percent higher than normal practices) with a row spacing of 15 inches or less. A higher seeding rate combined with narrower row spacing accelerates the time to canopy close. If a 15-inch planter or drill is not available, a 30- or 20-inch planter can be used by double planting parallel, perpendicular or at an angle to the first pass using a half seeding rate for each pass.
Step 5: Making the Decision
After gathering information about the injured crop and potentially replanting soybean, make your replant decision based on the best economic outcome of the two choices. Simply put, will the costs and yield potential of the existing stand have greater revenue than replanting?