C.O.R.N. Newsletter: 2026-27

Season 4, Episode 10 of Battle for the Belt is now available: https://youtu.be/Cb8ptOhLPwk

In Episode 10, we hear from Dr. Kelley Tilmon, a field crop entomologist with Ohio State University. Kelley discusses the late-season insect pests to watch for in corn and soybeans, including key scouting considerations and management thresholds.

As the growing season progresses, most insect management concerns in corn have passed, but a few late-season pests may still warrant attention. In soybean, the primary late-season concerns are defoliating insects, stink bugs, and bean leaf beetles (Figure 1).These pests can be particularly important in soybean fields that remain green while surrounding crops and vegetation begin to dry down. These greener fields can attract insects looking for a source of fresh foliage. Stink bugs and bean leaf beetles can also feed directly on developing soybean seeds within pods (Figure 2), making scouting important during this time of year. A sweep net is a useful tool for monitoring these pests and determining whether populations have reached treatment thresholds. For insect identification, scouting information, and current treatment thresholds, consult the Michigan State University and Ohio State University Pest Management Guide for Field Crops Insects: https://aginsects.osu.edu/sites/aginsects/files/imce/IPM%20Guide%20FULL%20-%20OSU%20%28002%29.pdf  as well as the short extension guides available through the Ohio State University Agronomic Crops Insects website: https://aginsects.osu.edu/.

Crop Update

Soybeans across the state continue to progress well, with all April- and May-planted soybeans reaching the R5 growth stage, while June-planted soybeans are only slightly behind. Recent rainfall across the state may help maintain soybean yield potential, as most soybeans are well into their reproductive stages when water demand is high. Approximately 60% of the water needed to meet soybean water use occurs between the R3 and R6 growth stages. With many fields currently in or approaching this period, adequate soil moisture will be important for supporting continued pod and seed development and protecting yield potential.

Corn is also moving along well. At the Western location, early April-planted corn has reached R5, or the dent growth stage (Figure 3). This dent that forms is a result of decreasing moisture content and increasing starch content within the kernels. Environmental stressors that may occur during the R5 growth stage can have the potential to reduce carbohydrates provided by the plant, ultimately limiting kernel weight and overall yield. Late April- and May-planted corn at this location has reached the R4, or dough, growth stage. The June 3 planting date has recently entered the reproductive stages at R1, while the June 24 planting date remains in the vegetative stages at V14 (Table 1).

Table 1. Precipitation, soil temperature, average air temperature, cumulative growing degree days (GDDs), and stage at the Western Agricultural Research Station, the Northwest Agricultural Research Station, and Wooster Campus. Weather data retrieved from: https://weather.cfaes.osu.edu/

Keep following ‘Battle for the Belt 2.0’ this growing season to learn more and get further updates! You can find the full video playlist of Battle for the Belt on the Ohio State Agronomy YouTube channel. 

Climate Summary

Recall August 2025 was the driest August on record for Ohio. The same cannot be said for August 2026, as it is shaping up to perhaps become the wettest August on record. In last week’s article, we mentioned the stormy week that lie ahead with 3-6 inches anticipated across southern Ohio. Although locally heavier amounts were possible, some locations received much more than expected. Figure 1 shows rainfall totals and percent of normal rainfall for August 10 – 16, 2026. Most areas from west central through central and southeast Ohio received 3-6 inches of rain. Particularly hard hit though were Fairfiled, Morgan, Muskingum, and Perry counties where officially more than 11 inches fell in New Lexington, with unofficial measurements as high as 15 inches. Two major rounds of rain brought catastrophic flooding to Crooksville and Roseville where businessnes and homes were flooded multiple times, even washing away donated items that were dropped off after the first bout of flooding. Portions of west central Ohio (e.g., Darke, Logan, Miami, and Preble counties) picked up 6-8 inches last week as well. Agriclutural impacts include flooded corn, soybean, and hay fields with varying degrees of damage, wind damage to barns and other structures, and livestock fatalities.

Figure 1) left) Total (inches) and right) percent normal precipitation for the period August 10-16, 2026. Figures courtesy of the Midwestern Regional Climate Center (https://mrcc.purdue.edu/).

As if flooding rain was not enough, multiple rounds of severe weather were felt across the Buckeye state. At least three tornadoes have been confirmed (south Columbus, Fletcher, and St. Paris) with the National Weather Service conducting damage surveys in other areas (Adams, Brown, Madison counties). Overall, temperatures were a bit warmer than average except in the areas with the persisten rainfall. For more monthly and quarterly updates, please visit the State Climate Office of Ohio or sign up for email updates at https://go.osu.edu/oh-climate-summaries. 

Weather Forecast & Outlook

Our persistent weather pattern will break down a little this week though precipitation is still in the forecast. High pressure on Tuesday August 18 will bring a welcome drier pattern and comfortable temperatures in the upper 70s to low 80s. A weak system could bring a round of showers through Ohio on Wednesday, lingering across southern Ohio into Thursday before Friday brings less humid conditions. Scattered showers and storms are possible over the weekend, but widespread activity is not expected. High temperatures in the upper 70s to low 80s are forecast all week. The National Weather Service precipitation forecast shows 0.25-0.5 inches of rain across the state over the next 7 days, though locally heavier amounts are possible where stronger storms occur (Figure 2).

The 8–14-day outlook from the Climate Prediction Center for the period of August 24 - 30, 2026, and the 16-Day Rainfall Outlook from NOAA/NWS/Ohio River Forecast Center show temperatures are leaning toward above average with near normal precipitation (Figure 3). Climatology for this period indicates a normal high-temperature range of 81-85°F, a low-temperature range of 60-64°F, and weekly total precipitation of 0.5-0.7 inches.