Crop Update

May has been a cold and wet and many farmers are struggling to get crops planted. Some for the first time. Others are already replanting. Although a week old, May 18th USDA's crop progress report is probably fairly accurate with the recent rains. Estimates are that only 34% of corn acres are planted in Ohio, with 22% of corn emerged. Emerged acres are probably higher by now. Corn planting progress was behind the 5-year average (48%), but corn emergence was slightly ahead (20%) as of May 18th. For soybeans, 40% of soybean acre were planted and 24% of soybeans emerged. On corn, some farmers got a few acres planted in late April when the air temperatures for a short period of time were warmer. but soil temps were cool. That corn either emerged, rotted or the soil got hard and struggled to emerge. Corn needs to come up within 3 days of each other for optimal yield. Cold wet weather causes many mineral deficiencies since the microbes in the soil are not warmed up and repopulating. Yellow corn may be due to nitrogen and or sulfur deficiency but also iron and magnesium deficiency. Purple corn is phosphorus deficiency and is seen around the base of emerging corn stalks and on the leaves. Corn potassium deficiency shows yellowing and even browning of leaves along the outer edges of leaves. Symptoms start on the leaf tip and move towards the leaf base. Signs include stunted growth, weak stalks, lodging, and poor root development. Early on, some sun and warmer weather help plants and microbes grow better and hopefully the crop improves.

For corn replant decisions, check out Ohio State University replant decisions. First check your fields in several locations to see what is the average stand estimate. According to Nafzinger’s 1995 Illinois research, at 30K to 35K final stand at harvest, corn planted towards the end of this week has a yield potential of 80% up to 90%. Corn planted late April with 20-25K population can still yield 90-97% of its full potential yield. Corn yield loss resulting from delayed planting can be about 1.75 bushels per acre per day according to However, some years, with good rains and good weather especially at pollination, farmers can get full yield. However, if the corn struggles and rains are scarce, late May and June planted corn can struggle with dry weather.

For most farms, getting a new corn crop planted first should be the priority. If you have extra help and another planter, replant corn. Often farmers spot in wet areas and where corn has come up unevenly or has major gaps. Replanted corn may cause problems with nitrogen side dress and also with harvesting.

On soybeans, many farmers now plant soybeans at the same time as corn, even first sometimes. Just like corn, soybean yield losses from delayed planting range from 0.25-1.0 bushel per acre per day. Soybeans are a little more forgiving on yield based on soybean population. Soybeans bloom throughout the growing season, and they have the ability to branch out and bush out to compensate. However, the stand needs to be consistent, which seldom happens.

For soybeans, replant is recommended at less than 50,000 (50K) plants per acre if the stand is uniform. For many farmers in Northwest Ohio, beans are often drilled at 150K to 200K/acre. For non-uniform soybeans, consider replanting at <75K plants per acre. Ohio State University research shows that reduced soybean populations of 100K going down to 50K plants per acre resulted in only a 9 to 14% reduction in soybean yield.

“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.” Source: Dr. Oslo Ortez, Dr. Laura Lindsey, and Eric Richer, Ohio State University, CORN Newsletter.