This past week saw hail, substantial rain, and missed opportunities for needed precipitation in varying fields across the northeast region of Illinois. Corn has reached R3 or the milk stage in the field I have been scouting this summer. At this stage the kernel no longer adds new cells to the kernel endosperm but fills the existing cells with liquid starch. If punctured the liquid or “milk” will spray or shoot out of the kernel. Foliar disease pressure in this field continues to be low, I have noted very sporadic purplish lesions in leaf midribs and on corn stalks. This is symptomatic of the fungal disease Physoderma brown spot. Especially on lighter soils or areas where significant nitrogen loss occurred, likely due in part to extreme rainfall, considerable remobilization of carbohydrates is taking place as corn plants cannibalize lower leaves to meet their nutritional needs of ear development. Soy has reached R4 or full pod stage, the beginning of a critical stress response period for the soy plant. New flower growth slows and plants lose their ability to remake new flowers and pods. Similar to the corn crop, disease and insect pressure currently are low in the 2026 soy fields I have visited.

Crops are looking good. Soybean fields are not showing any signs of disease symptoms in the upper soybean canopy. Corn is advancing to the dough stage in early-planted fields.The majority of central and eastern portions of Illinois have had below normal rainfall for the first 29 days of July, as evidenced by the brown grass in pastures, lawns, and roadsides.

Corn and soybeans are progressing well in northern Vermilion County, as full-season crops are entering key grain fill stages. Impacts from wet weather early in the season can still be seen in low-lying fields, with uneven growth stage and canopy where the crop survived. Conditions have been a bit dryer in the region over the past several weeks, and surface soils are starting to crack. That said, crops do not appear to be experiencing much stress at this point, as they are likely able to access moisture deeper in the soil profile.

Most full-season soybean fields were somewhere in the pod development stages (R3-R4), and the few double-crop soybean fields I found were in the V2-V3 range. Disease and insect pressure still appeared to be low in most soybeans, but weeds were a different story in a handful of fields. Corn generally ranged from R1 (silking) to R3 (milk). I found a couple fields with some mild aphid pressure, and foliar symptoms of nitrogen deficiency could be found in the lower canopy in those areas affected by the early-season moisture and subsequent soil conditions. Foliar disease symptoms can also be found in these areas where plants are stressed, but healthy corn still looks relatively clean of foliar diseases.

Hot and mostly dry conditions continue across the area, with daytime highs in the 90s and soils beginning to crack from limited moisture. Fields are considered mildly dry, which is not uncommon for this region that often misses rainfall events. Ground rigs and airplanes have been busy with fungicide and insecticide applications, while fields with significant weed escapes are receiving additional post treatments. Soybeans are generally at the R1-R3 growth stages. Areas that received heavy early-season rains have faced greater weed control challenges throughout the season.

Crops are generally looking good. The exceptions are fields that suffered earlier issues of waterlogged soils or storm damage. Amaranth weed control has been a problem for non-GMO soybean producers relying on Group 14 herbicides, with insufficient early-season herbicide control of these plants. Dr. Aaron Hager’s research shows improved amaranth control in non-GMO soybeans when metribuzin is applied at appropriate rates either PPI or at planting. Soybean fields vary from the R1 to R4 growth stages.
No-till double-crop soybeans are growing very well, reaching the V3 stage.
Corn fields vary from almost VT to R3 stage. Nitrogen deficiency is apparent in fields where there were waterlogged soils. Corn leaf diseases are beginning to appear – Gray Leaf Spot. Physoderma Brown Spot can be seen in a few isolated fields in the low areas where water stood earlier in the season.

Timely rainfall across our region brought much-needed relief, helping ease the extreme heat last week and providing more favorable conditions for both the crop and fieldwork. While the cooler temperatures are welcome, they may also create an environment that allows corn and soybeans diseases observed earlier this summer to become more active again. The prolonged stretch of hot halted disease progression over the past few weeks, but we’ll continue to monitor fields closely.

Overall, the crop remains in good condition as corn transitions from pollination into grain fill and soybeans move into pod fill. Continued rainfall over the next few weeks will be critical to help maximize yield potential and carry the crop through the remainder of the growing season. Fungicide remains in full swing this week, with acres being treated by drone, helicopter, airplane, and ground sprayers. Growers work to protect crop health during these key reproductive stages.