I have received a few reports of corn leaf aphid. This insect should be scouted prior to tasseling, during late vegetative stages; if you have colonies of aphids formed on around 50% of plants at this time, you should consider an insecticide. Beneficial insects and fungal pathogens usually do a number on this pest, and it takes extremely large populations to impact yield.

We received some much-needed (if sporadic) rainfall in the last week that has crops looking much better than in previous weeks. Areas of Bureau County reported over 5 inches on Friday night, though that storm system petered out by the time it reached LaSalle County. LaSalle County did receive about 2 inches of rainfall on Wednesday night. Thankfully, temperatures have also cooled off a little bit for the time being, and there is more rain in the forecast for this weekend and early next week.

Overall, crops are looking healthy. Wheat in LaSalle County was harvested the first week of July. Most corn is now reaching VT/R1. Most soy is entering reproductive stages, with many fields at R3. I have not seen any serious disease or pest concerns in the fields I have scouted, but tar spot has now been reported in LaSalle, Bureau, and Marshall counties, so growers should continue to scout fields and be on the lookout for this disease. Corn is reaching the growth stages where it could benefit from a fungicide application, and I have seen both ground and aerial sprayers at work in the past week.

The rains have finally arrived in northern IL, with a handful of widespread storm events and more starting this weekend and pushing into next week. Most areas have reverted to D0 or D1 drought status, and crops are doing well. Will County is the only area still in a D2 drought. With the rain and cooler temperatures in the forecast, disease may finally start to creep into our corn and soybean plots. This late in the season generally won’t have a large impact on yields, but scouting is still recommended through ear fill in corn, as well as scouting for white mold and frogeye in soybeans.

Corn is tasseling across the I-80 corridor. The DeKalb area was around 80% of fields at VT/R1, with the stragglers around V12/13 and spiking. Corn blotch leafminer is showing up in the lower leaves of multiple fields I scouted between DeKalb and Crystal Lake. This is also the kind of weather tar spot thrives in — wet, with intermittent rains and cooler temperatures overall. I would not be surprised if it is already in fields in northern IL or develops quickly with the upcoming forecast. Scouting is your best measure to know if it’s in your fields, as always. Corn overall is healthy, and I have not seen any fields with wind or hail damage despite the severe weather we have been seeing.

Soybeans are pushing quickly through growth stages. Most bean fields I scouted are in R3 and nearing R4 very quickly, if they aren’t already there. Disease pressure is low currently, with small amounts of Japanese beetle damage, but nothing that will lead to economic loss. I will be scouting heavily for white mold, SDS, frogeye, and other fungal diseases in the coming weeks if the water has turned on and stays on.

Spotty storms this week have dumped 1″–3″ of rain across Marion County after our longest stretch without precipitation since March. Our soils didn’t get dry exactly, but this moisture will help see the crop through the heat. This rain also helped even out some stands of double-crop soybeans in spots where the seed didn’t quite make it through the straw down into the soil and had yet to germinate. Most double-crop soybean fields I’ve seen are at V2 and looking good. First-crop soybeans are R1–R2 unless they were planted or replanted late. There were still planters rolling the first week of July, and those are more on pace with the double crops.

Corn in the area is still in vegetative growth stages, but you can feel the tassel forming down in the whorl, so VT is on the horizon.

For a more upbeat report, I would encourage you to read my coworker Steve Brand’s report. Last week, in the area Steve covers in Northern Illinois, many fields received between 3 and 5 inches of rainfall. In areas including Kendall, Grundy, and Will, the rainfall totals measured in tenths. As many corn fields are at or nearing VT and R1 (tassel and silk stage), an expected result of the moisture stress is kernel abortion. Moisture stress at this time can interfere with pollen shed and silking synchronization. In addition, high temperatures coupled with low humidity can desiccate exposed silks.

Can farmers evaluate the pollination process? After successful pollination and fertilization of the ovules, the silk will detach from the developing kernel. Evaluating pollination success can be done with the ear “shake test.” Carefully unwrap the husk and gently shake the ear; the silks from the fertilized future kernels will readily drop off.

As long as we have kernels and green tissue for photosynthesis, we can remain hopeful for the corn crop. Our soy crop, while visibly shorter this year in the dry fields, can recover more readily if forecast moisture alleviates growing conditions in this area.

Depending on location, we have received between 1.5 and 4 inches of rain in the last week. It had previously been very dry in some areas, while others were lucky enough to get some pop-up showers. We now have the conditions for diseases to start showing up in corn or soybeans, but this will also depend on their disease susceptibility or disease scores. A few Northern corn leaf blight lesions were present in corn, but I was more concerned with the spread of gray leaf spot from the lower leaves. Japanese beetle infestations have ramped up, especially in later-planted soybeans. If farmers have decided to make fungicide/insecticide applications, they will start on corn this week as it has reached the VT growth stage. Early-planted soybeans have canopied and will soon reach the R3 growth stage. If warranted, they will also receive fungicide/insecticide applications at R3.

In Franklin County this week, I found a couple of soybean fields in full flowering (R2), despite being shin-knee high. Beans in this area vaulted straight into flowering at only V5–V6, since days have started shortening after the solstice. Most double-crop beans are in the ground and at VE–VC.

On the corn side, I have seen one field tasseling — it must have been an atypical field that got planted in April. Most corn fields are still vegetative (V9–V10), with no sign of tassels yet.

The growing season is entering a key phase, during which many fields and plants are transitioning into the reproductive stage of growth. Nearly all of the corn fields in the area have entered the R1 phase, with some likely further along. There are still some fields in the later V-stages, but they won’t be behind the rest for too long. Much the same story can be said of soybeans, with some more mature fields in the R1–R2 phase, while others are in the later V-stages. Rainfall has also been variable across the area over the last week. Some parts of the county received around an inch of rain, while others received a half-inch or less.

Now is the time to begin monitoring corn rootworm beetles — both to evaluate the performance of traits/insecticides used this year and to gauge the need for control next year. We will again be distributing yellow sticky traps to anyone interested in participating in our regional corn rootworm adult monitoring network in 2025 (for more information about the network and to see reports from previous years, visit www.rootwormipm.org).

If you are interested in participating and would like me to send you traps and/or the sampling protocol, please send me an email (nseiter@illinois.edu) with the following information:

• Your name and shipping address
• The number of corn and soybean fields you plan to monitor

Currently, the corn and soybean crops are looking good. Some corn in the drier areas has fired on the lower leaves.

Soybeans vary from V5 to R3 (beginning pod), and corn varies from V10 to R2 (blister), with most of the corn crop in the R1 stage. Weed control is generally looking good; however, the amaranths are beginning to poke above the soybean canopy in some soybean fields.

Rainfall over the past 14 days has been over 150% of normal in southern Macon and Piatt counties, and less than 25% of normal through the balance of the three-county area.