As of May 18, 2025, USDA’s crop progress report estimated 34% of corn acres planted in Ohio, and 22% of corn emerged. Corn planting progress was behind the 5-year average (48%), but corn emergence was slightly ahead (20%). On the same report, 40% of soybean acres were planted and 24% of soybeans emerged. Soybean planting and emergence progress were ahead of the 5-year average (39% planting, 14% emerged).
Weather, pests, and diseases can affect seedling vigor, plant growth, stand establishment, plant population, and crop yield. This year’s early planting dates have been affected by a combination of cold air and soil temperatures, precipitation, and recent storm events (including hail) in some parts of the state, which may lead to reduced stands. Some stress factors can include imbibitional chilling, soil crusting, standing water, frost, slugs, and disease.
If reduced stands are a concern, a potential option to consider is to replant fields. However, replanting does not always translate into better yields. Here is a list of aspects to look at if you consider replanting:
Step 1. Wait… Plant stands should be assessed after ‘stable’ and ‘better’ conditions are achieved to allow the chance for seeds to germinate/emerge (e.g., warmer temperatures, better soil conditions). Often, hasty decisions are not the best.
- For corn, past work has shown that 50% emergence can be expected following the accumulation of 100-150 soil GDDs (base of 50°F) from the time of planting. This can be achieved in about 5-7 days under adequate temperatures and soil conditions.
- For soybean, assess the stand at the VC growth stage. Visual stand assessment at the VE growth stage often underestimates the total number of plants that will emerge.
Step 2. Estimate the number of plants per acre from several areas within the field by conducting stand counts. Field variability exists, and collecting stand counts from several representative areas is important (Figure 1).
Figure 1. In-field plant emergence variability in corn. Left and right plants with more growth and development relative to the plant in the center. Source: Osler Ortez.
- For corn, after estimating the number of plants per acre, for reference, you can use Table 1 to locate the expected yield of the plant stand depending on the planting date. Then, locate the expected replant yield by reading across from the expected replanting date to the stand that would be replanted. The difference between these numbers is the percentage yield change (increase or decrease) expected from a replanting decision.
Table 1. Replant Chart Developed Under High-Yielding Conditions (adapted from the University of Illinois - Nafziger, 1995-1996).
|
|
Plants per acre at harvest |
|||||
|
Planting Date |
10,000 |
15,000 |
20,000 |
25,000 |
30,000 |
35,000 |
|
% of optimum yield |
||||||
|
April 10 |
62 |
76 |
83 |
92 |
94 |
93 |
|
April 20 |
67 |
81 |
91 |
97 |
99 |
97 |
|
April 30 |
68 |
82 |
92 |
98 |
100 |
98 |
|
May 9 |
65 |
79 |
89 |
95 |
97 |
96 |
|
May 19 |
59 |
73 |
84 |
89 |
91 |
89 |
|
May 29 |
49 |
62 |
73 |
79 |
81 |
79 |
- For soybean, if the plant population is relatively uniform, replant is recommended if the stand is less than 50,000 plants per acre. If the plant population is non-uniform, farmers may want to consider replanting at <75,000 plants per acre. Although the stand will look poor, soybean plants can compensate for low plant populations by increasing the number of branches (Figure 2). In our research, going from 100,000 to 50,000 plants per acre resulted in only a 9 to 14% reduction in yield.
Figure 2. Soybean plants seeded at 100,000, 140,000, and 180,000 plants per acre. Source: Will Hamman.
Step 3. Check the weather forecast. How soon can you get back to the field to replant?
- For corn, early planting dates with lower stands can still produce good yields. From past research, a stand of 20,000-25,000 plants per acre planted on April 20 can still yield 91-97% of the optimum yield. Corn yield loss resulting from delayed planting can be about 1.75 bushels per acre per day.
- For soybean, the date of planting has more effect on soybean grain yield than any other production practice. Yield loss resulting from delayed planting can range from 0.25 to 1.0 bushel per acre per day.
Replanting at later dates, past the recommended window (late April or early May), may result in lower yields compared to having lower plant populations planted earlier in the year. Seed cost and labor should be considered. When low plant populations exist, a common question is whether to replant fields or not.
Another factor is crop insurance. For those who carry Multi-Peril Crop Insurance (MPCI) in the form of Revenue Protection (RP) or Yield Protection (YP), we encourage you to discuss replant provisions with your agent if plant population is a concern. Per crop insurance policies, the insured must file a replant claim and speak to an adjuster before taking any replant action. The standard 2025 replant coverage per acre for corn is 8 bushels x $4.70 (Projected Price) = $37.60/acre. On the other hand, the standard 2025 replant coverage per acre for soybeans is 3 bushels x $10.54 (Projected Price) = $31.62/acre. Additionally, a minimum of 20 acres or 20% of the acres per unit must qualify for replant before the standard policy provides coverage. If feasible, utilizing crop insurance is one of the many tools to manage/mitigate risk in farming operations.
Replant recommendations for corn and soybean are an active area of research. In 2025, we started a new project aimed at revising replant decisions for corn and soybean. The project is funded by USDA-NIFA-AFRI under the Critical Agriculture Research and Extension (CARE) program, with the main goal of identifying soybean and corn replant thresholds based on plant populations and planting dates for three distinct growing regions in Ohio. Stay tuned for more updates and results on the new project.