Contrary to what you might have read on social media or heard at the coffee shop, it’s true –  southern Illinois has received an extreme amount of rain this spring, and many farmers have not been able to plant yet in 2025. I know this firsthand because the rain has had an impact on our own family farm just south of Illinois Route 16.

Credit – IL State Climatologist

If you still have both corn and soybeans to plant past mid-May, it is time to focus on corn. Soybeans are photoperiod sensitive, meaning they can adjust their development due to late planting. Soybeans are more apt to yield under stress when compared to corn.

In northern and western Illinois, where dry conditions have caused crusting and poor germination, seed may be safer in the bag than being in the ground. Drought stress has the greatest impact on yield during germination, just as much as it does during reproductive seed development. Early-season soybean stress may cause leaves to be smaller or limit vegetative growth; therefore, more energy and efforts may be given to root development. Ultimately, nitrogen fixation can be severely limited or completely halted by even moderate drought stress.

Graph taken from: Illinois Corn Management 2025

All is not lost yet. The planting date is not the only management decision that can lead to greater yield. Other management factors, along with Mother Nature, determine yield potential during the rest of the growing season. Here are some late planting tips or watchouts:

• No matter how late you plant, don’t “mud it in.”
• There are concerns about nitrogen loss if anhydrous or another nitrogen source was applied earlier in the spring. Those who used N-serve with their anhydrous may have an advantage over those that did not. While temperatures have been cool, I have no doubt that some of this nitrate has been lost, depending on soil conditions, in southern Illinois. Keep an eye on corn to see if supplemental nitrogen is needed. Those that implement cover crops can reduce nitrogen losses by 25% to 30%.
• Be sure to double-check all the labels of the herbicides that have been applied to a field before switching from corn to soybeans.
• We normally don’t need to change or go down in soybean maturity until mid-June in the Midwest. There is only a three-to-five-day difference between a maturity group spread of .5 to 1.0. If the same variety was planted 40 to 60 days apart, the latter planted would reach maturity 5 to 10 days later depending on light, heat, moisture, and nutrients.
• In a later growing season, fewer nodes may develop on the main stem, with less days to flower, which could decrease yield potential. As we approach mid-May, if you can plant, start increasing your “normal” soybean planting population (< 140,000 seeds/A) by 3 to 5% until June because of plant stature. If soybeans are still not planted by June, it is recommended to start to increase seeding rates by 10%. Increasing soybean populations will not necessarily always guarantee a higher yield, but they can help to attain a greater number of nodes for trifoliate leaves to capture sunlight during a later growing season characterized by shorter daylight hours.
• Increasing soybean populations may improve plant height as well as produce pods higher off the ground, reducing harvest loss and lower branch breakage.
• Narrow row spacing can help you get on average, a 5% to 10% yield advantage because of the potential for quick canopy or row closure which can lead to increased sunlight capture, shading of weeds, and reduced soil evaporation.
• Seed treatment is usually not a necessity with later planting but still may be needed if Phytophthora root rot is a threat. Refer to this article I wrote, “You Think Your Soy Has the Blight: Now What?”
• Fields that are not planted yet may be greening up now with summer annuals like waterhemp because our fall or spring burndown did not happen, or the spring burndown or tillage occurred earlier this spring. Focus on the new weeds coming because they could haunt you the rest of the season. Another herbicide burndown with higher rates of residuals may be needed depending on weed, label, and plant back restrictions before tillage or planting. Late season scouting for weeds will be critical.
• Be careful and read herbicide labels when making later post or rescue applications to avoid the risk of carry-over into the next cover crop or even crop.
• Disease susceptibility will vary depending on soybean variety but increasing soybean population and decreasing row spacing can create a more favorable environment in certain weather scenarios for white mold, charcoal rot, stem cankers, and possibly some leaf diseases.
• You may avoid some of the soybean insect pests by planting later. However, be on the watch for soybean aphid and later-season insects such as stink bug and grasshopper, which may not be controlled with an insecticide application at the R3 growth stage.