For many Labor Day weekend is considered the unofficial end of summer. For the ag community in Northeast Illinois the end of summer is the Sandwich Fair, held annually the week following Labor Day. Yesterday I had the opportunity to judge commercial corn entries at the Horticulture and Crops barn at the fair, Using the size and kernel number of ears as an indicator, it has been a good growing season. In the field, both corn and soy are nearing maturity, in most fields I observed it appears corn is winning the race. Most in this region will likely start the 2026 harvest in corn before soy. As farmers prepare for the harvest this is an ideal time to check corn fields for any standability issues. This can be accomplished by walking the field or by use of a drone. With this knowledge, field harvest order can be adjusted accordingly. With the variability we have seen within fields this year it will be important to check combine settings often during crop harvest.

Harvest has begun in northern Champaign County, albeit on very limited acreage, primarily seed corn fields at this point. Another week of dry weather along with high temps in the 90s have dried up any standing water that remained in fields in that part of the county and has moved the corn crop, in particular, much closer to harvest. Most corn fields I visited still have not quite hit full physiological maturity (R6), but with the milk line all but disappeared on most ears, they don’t have far to go. Ear size and grain fill was once again variable. Foliar diseases in corn are “helping” to turn fields from green to brown quickly at this time of year, and I’ve seen a bit more lodging in corn fields as the weeks progress. In fields surveyed with lodging issues, the main culprit appeared to be Diplodia stalk rot. But other stalk and crown rots could be contributing to this issue as well. I’ll reiterate my message from last week encouraging the use of recent drone or satellite imagery to asses lodging severity in fields to aid in harvest decision making. Soybeans are also progressing towards maturity, but many fields remain with plenty of green in the canopy, still somewhere between full seed (R6) and beginning maturity (R7) growth stages.

Entering September an intense shift in weather as a “heat dome” became established in Northeast Illinois. While fields near the Wisconsin state line received precipitation, most areas did not. The ninety degrees plus days provided ample Growing Degree Days (GDDs) for crops finishing grain fill. On lighter soils the temperatures are causing a water deficit reflected by the wilting/yellowing plants. As mentioned in previous reports, there is very good corn, and not as good, depending on where you collect samples. This week I collected from fields that should be very high yielding.

Few things are left to surprise me in this growing season, but a sunflower field in Kendall County did just that! Not sure when the field was planted or harvest plans for the crop, but an interesting rotation option. Several winter wheat fields that had been harvested earlier in the season are now supporting a robust weed population. Farmers should consider mowing, tillage or a chemical option to prevent these weeds from adding to the weed seed bank. For those considering a third or fourth cutting of alfalfa, an often asked question is when? Adequate time is needed for regrowth of alfalfa to replenish root carbohydrates to increase overwintering ability of the perennial crop. Our general answer has been four to six weeks before a killing frost for the hay crop. Newer recommendations encourage farmers to look at GDD’s, with a minimum of 500 GDD’s between last cutting and a killing frost.

Early-maturity soybean fields are turning yellow and shedding leaves as they approach the R8 (Full Maturity) stage. Most soybean fields are just beginning to show a little yellow.
Corn harvest has just started, with a few farmers taking out end rows and taking advantage of local elevators offering reduced drying charges for corn at moisture levels under 30%. Corn root and lower stalk samples from fields with lodging issues were submitted to the U of I Plant Clinic and were diagnosed with both Rhizoctonia crown and stem rot and Pythium crown and/or root rot. Corn ears are varying quite a bit in size within fields.

After a week of some welcomed dryer weather, and perhaps less welcome heat, the crop in southern Vermilion County is progressing quickly towards maturity.

Most soybean fields in that part of the county were somewhere in the full seed (R6) growth stage, with a couple fields starting to drop leaves and close in on beginning maturity (R7). Some pockets with disease issues could be found and are relatively easy to spot at this point in the season, as they tend to be a bit stunted and yellowing/dropping leaves faster than surrounding areas. But for the most part, most fields are relatively clean of disease as they near maturity.

Most corn fields are somewhere in the dent (R5) stage. I did not find any kernels at black layer in the fields I surveyed, but there were at least a couple fields that were very close. As these fields senesce, more foliar disease can be seen in the canopy as well. Even if it won’t impact this year’s management decisions, now is a good time to scout your fields to determine how well your disease management plan worked this year. Over time, these observations can help you determine which diseases may be more prevalent in certain fields as well as help you determine the influence of genetic resistance in your chosen hybrids to different diseases. Another reason to scout now is to asses the levels of stalk rot and lodging in your fields. I found a couple fields during my survey with some localized lodging due to crown and stalk rots. The use of drones or recent satellite imagery, if you have access, may help to assess extent and severity of lodging and help with prioritization of harvest activities.

Harvest season is coming in HOT! Literally… as temperatures are reaching 100°F in many areas of central Illinois this week.

It seems that September 1 hit and soybean fields started turning, as many full-season beans in these counties are hitting R7 (beginning maturity) or pushing R8 (full maturity). A few farmers have begun dipping their toes in corn harvest, as I saw a few guys stripping off end rows. This high heat will accelerate crop dry down, especially since early-planted crops were already pushing maturity in many areas of Sangamon, Christian and Montgomery counties. Fall is definitely whispering to us and I expect harvest to be in full swing within the next couple weeks.

Earlier-planted soybean fields are beginning to turn color, signaling the Beginning Maturity (R7) stage. Other soybean fields are mostly in the Full Seed, R6 stage, and no longer blooming.
Earlier-planted corn fields are looking ugly with areas of the fields showing severe N-deficiency symptoms and dead plants, which is indicative of a root or stalk disease issue. Corn crown rot is suspected to be the cause in some of the fields. I currently have several corn plant roots and lower stalks being analyzed at the U of I Plant Clinic in the hope of determining the cause or causes. Local farmers are preparing for a challenging beginning to their corn harvest in the area.

Black layer is near for some corn fields in the Northeast region. Utilizing the U2U Decision Support Tool – Corn GDD suggests a 108-day Hybrid planted April 25th in Grundy County will reach black layer between September 1st and the 6th. In corn fields scouted, especially those that did not receive a fungicide application, foliar leaf diseases continue to hasten leaf area necrosis and yellowing of plants. This is going to be a challenging year for accurate corn yield prediction from the perspective of in-field variation. Growers are encouraged to sample multiple locations within the field, accounting for pollination differences in ears to more accurately assess predicted yield. Some soy fields are starting to show very limited disease symptoms including Sudden Death Syndrome. This fungal pathogen can survive the winter in both corn and soy residue. Infection takes place early in the growing season, enhanced by cool and wet soil conditions. The visible symptoms we see are the result of a toxin produced by the disease that is translocated to upper canopy leaves. There are several other diseases including Red Crown Rot and Brown Stem Rot that exhibit similar leaf symptoms.

Both corn and soybean fields are maturing well and looking promising… or they suffered from recent heavy rains/winds and are visibly struggling. While flooded fields have mostly drained over the past week, you can still see the evidence of high waters in bean fields where plants were drowning and are now painted in a layer of soil, or in corn fields showing N deficiencies and early dry down. Some areas that needed the precipitation have soaked it up and appear dry again. The precipitation received this month, coupled with the more mild temperatures, will really help the soybeans as they finish off grain fill. As the saying goes: Beans are made in August.

One insect I’ve seen a lot of lately is thistle caterpillar. Thistle caterpillar, the larval stage of the painted lady butterfly, will build a very distinctive web in soybean leaves and cause defoliation. Threshold levels for control have not been met in fields I’ve scouted, but one double crop field I visited had notable pressure. Per Iowa State University Extension, these caterpillars are a migratory pest, coming north from the southern United States and Mexico, and likely do not overwinter in our climatic region.

I visited Ford County this week, and like Champaign County, flooded conditions have returned to areas affected earlier this growing season. The flooding seemed to be a bit worse in the southern part of the county and improved as I traveled north, which is consistent with precipitation estimates from MRCC and rain gauge data from ISWS and CoCoRaHs from the past couple of weeks. To some extent, the flooded areas are already absent of a crop due to early-season flooding. But in a number of fields I stopped at, the current flooding extended into previously healthy crop. That crop is now either dead or has signs of stress, disease, and early senescence, leading to incomplete grain fill, low seed weights, and potential grain quality issues.

In fields or areas not affected by the flooding, soybeans are at or near full seed (R6). Soybean canopies, for the most part, were still relatively clean of disease, but a minority of fields do have some disease symptoms starting to show in patches. Disease symptoms were a bit more prevalent in corn fields visited, primarily gray leaf spot and northern corn leaf blight, but severity was still relatively low, overall. Corn was generally somewhere in the dent (R5) growth stage, getting close to black layer in a handful of fields.