Consistent rain throughout Knox County has resulted in planting delays. According to the National Agricultural Statistics Service (NASS) 34% of the corn and 40% of the soybeans have been planted in Ohio, through May 18th . In Knox County our corn numbers are higher than that. For the month of May (through 5/20) we have recorded 7.71 inches of rain at our weather station near Centerburg. As usual, some parts of the county have received more rain and other areas, not as much.
Some of the corn that has been planted may not survive the cool, wet conditions and therefore may need to be replanted. Replant decisions in corn should be based on strong evidence that the returns to replanting will not only cover replant costs but also net enough to make it worth the effort. The following information may help to determine if replanting is justified:
Original target plant population/intended plant stand. What was your intended plant stand, what is the stand count in the “good” areas of the field.
Plant stand after damage. To estimate after‑damage plant population per acre, count the number of viable plants in a length of row that equals 1/1000 of an acre and multiply by 1000, for 30 inch rows that would be 17’4″. Make several counts in different rows in different parts of the field to get a true representation of the field.
Uniformity of plant stand after damage. If uneven emergence is row to row, that is, most rows are emerged but some are not, replanting will likely not increase yield. If the delay in emergence is less than two weeks between the early and late emerging plants, replanting may increase yields, but by only 5% or less. Replanting would likely not be economical. Yet if one-half or more of the plants in the stand emerge three weeks later than the initial plant emergence, replanting may increase yields by about 10%.
Economics – Calculate expected yield from the existing stand and estimated yield from replant. The table below shows the effect of planting date and plant population on final grain yield. Grain yields for varying dates and populations are expressed as a percentage of the yield obtained at the optimum planting date and population.
For example: Let’s assume that a field planted on April 20 at a seeding rate sufficient to attain a harvest population of 30,000 plants per acre. On May 28 you determined the stand was reduced to 15,000 plants per acre as a result of saturated soil conditions and ponding. According to the table above, the expected yield for the existing stand (15,000 plants/ac.) would be 81 percent of the optimum. If the corn crop was planted the next day on May 29, and produced a full stand of 30,000 plants per acre, the expected yield would also be 81 percent of the optimum. The difference expected from re-planting is 0 (81 – 81) , which would not justify replanting costs. The cost of replanting a field is often the deciding factor. Costs include tillage, seed, fuel (for tillage and planting), additional pesticides, labor, etc. .
Can you get by with replanting certain areas of the field? This adds several more considerations in addition to those above. Replanting into existing stands (interseeding) usually creates competition problems with larger plants competing with smaller planes for all needed inputs throughout the rest of the growing season. Often the smaller plants will turn into weeds. The best option is usually to destroy the existing stand and start over.
With the continued rains this week it may also be time to consider a Prevented Plant conversation with your crop insurance agent and FSA.
The U.S. Department of Agriculture (USDA) today announced several Conservation Reserve Program (CRP) enrollment opportunities for agricultural producers and landowners. USDA’s Farm Service Agency (FSA) is accepting offers for both the General and Continuous CRP beginning today through June 6, 2025.
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