A favorable week for crop growth in the northeast region of Illinois. Corn is pollinating, despite predicted 90 degrees plus highs this week, most fields have adequate moisture and should not suffer despite elevated temperatures at this critical stage for the corn crop. I enjoy my early morning coffee looking across several corn and soy fields. This past week I noted most mornings start with a mist or fog. The mist does not come directly from the corn and soy crops, even though both put water vapor in the air through the process of transpiration. The morning mist is the result of the cooling of the moist air. As the air cools overnight, it reaches its “dew point” and can no longer hold water as a gas, causing water vapor in the air to turn into liquid droplets. Of significance to those scouting for crop diseases, the morning mist extends periods of leaf wetness, a favorable requirement to several fungal leaf diseases. This week, with the appearance of brace roots in the corn crop, the question of underground root expansion was raised. There are many limiting factors to root growth, too much or limited moisture, soil compaction or other natural barriers. However, the general suggestion is that root expansion in the corn crop continues through pollination. At this point the crop redirects energy toward grain fill. By this time with favorable soil structure, it is not uncommon for corn roots to extend to six feet in depth. Our soy plants tend to generate roots further into the vegetative stages, to R5 and R6, beginning and full seed.
The corn crop is R1 with kernel fertilization underway. Soy is between R2, full flower and R3, or beginning pod. Despite favorable conditions for leaf diseases, I have yet to see an outbreak of tar spot on corn or soy leaf disease in fields I have scouted. Growers are encouraged to remain diligent with both field visits and local reports.

This week farmland in the northeast region received additional precipitation and winds over the July 4th weekend. Rainfall totals reported ranged from 1+ inches to isolated fields that received 9+ inches. When sharing an update, the challenge is whether to report on the part of the field that has been unaffected (or even enhanced) by the rainfall, or the parts of the field that have been killed or damaged by ponding or saturated soils. Depending upon where you look, there are outstanding portions of fields, but if you evaluate the field as a whole and note the unevenness and drowned out areas the field overall rating diminishes. Soybean are at R2 or full flower, at this stage the plants begin a period of rapid dry matter and nutrient accumulation. This week shorter season or earlier planted corn hybrids have reached R1 or pollination and scouting for foliar leaf diseases has intensified. This job will soon be less pleasant when pollen shed increases. In fields scouted, I have yet to find symptoms of Tar Spot. I have noted black specks on corn leaves, but the Tar Spot stromata (lesions) cannot be brushed off. What I have found are either wind deposited dirt or possibly insect frass or excrement. If you can wipe off the black spot on a leaf it is not Tar Spot. Follow our weekly reports for updates on Gray Leaf Spot, Tar Spot, Southern Rust and other diseases found in both corn and soy across the state.

In a recent report, I stated that warmer weather would benefit the 2026 crop, perhaps in the future I should qualify my term of “warmer weather”. A week of 90 degree plus days in Northeastern Illinois has allowed farmers and agribusiness the opportunity to play catch-up applying post herbicides. Last week, you could not travel a rural road without meeting a sprayer. Most fields have weed populations that have easily exceeded weed size management recommendations and most have drowned out areas that will likely germinate later season weeds. Fields this year are unlikely to have “perfect” weed control. Growers are encouraged to evaluate post herbicide applications and start scouting for leaf diseases in corn. Tar spot symptoms have been reported in the state, and one tool that can be utilized to see if a crop disease has been reported in your area is visiting the Crop Lookout Website. Crop Lookout is a real-time, interactive map that highlights emerging field crop issues across the United States and Canada. Updated throughout the growing season by university Extension specialists and research partners, the tool visualizes reports of diseases, pests, and other agronomic challenges as they develop. Northern Corn Leaf Blight or Goss’s wilt have been found in Grundy County as the crop is near the Tassel stage.

Another week with precipitation, in many areas ground sprayers have been unable to operate since June 7th. Many fields that are inherently poorly drained are ponded and both corn and soy are suffering. Farmers are facing the challenge of post applications of herbicide for corn and soy, and in some cases nitrogen for the corn crop. Warmer and dryer weather is desperately needed for the crops in the area. Most soy in the area not stressed by saturated soil has reached R2 (full flower), corn has reached V11. Waterhemp has reached 18 to 24 inches in untreated fields. Area alfalfa fields are flowering and Japanese Beetle have emerged in Northeast Illinois.

When I left Illinois for a brief vacation the first week of June, the Northeast Region was dealing with impending drought concerns (note wrapped corn from June 4th). Twelve days and 5+ inches of precipitation for many acres, an entirely new set of concerns for the 2026 crop. New concerns relate to saturated soils, erosion and crop damage caused by moving surface water and wind, and the lack of opportunity to apply post herbicides while weeds are in the optimum treatment window. Even when standing water dissipates, a saturated soil very quickly limits oxygen availability to a growing crop. An oversimplified way of describing the effects of a saturated soil is that the lack of soil oxygen available to the roots can reduce or stop plant functions. This can include transpiration, nutrient uptake, and water uptake. Extended saturated soil can cause visible stunting and even plant death, resulting in varying degrees of reduced final yield. In addition to struggling crops, persistent precipitation has prevented many post-herbicide applications from taking place. A few weeds, especially waterhemp, easily have exceeded the recommended maximum weed size for control of most herbicide. Soy on well drained soils are starting to enter their reproductive stage (flowering). We are near halfway through the growing season and have experienced the environmental conditions of excessively cool, hot, dry, and wet; What’s next?

A dry week in the Northeast region, corn picked up one additional leaf (V6) and soy pushed out another trifoliate (now V2) in the fields that I am observing on a weekly basis. Hay harvest, nitrogen sidedressing, and post herbicide applications are all taking place. With the comparatively quick onset of dry conditions and stress on both crops and weeds, farmers are encouraged to evaluate post herbicide applications at least a week after application. Environmental stress, including drought, can slow active growth and herbicide solution absorption in plants, decreasing herbicide effectiveness on targeted weeds.

A warm and mostly dry week for growing crops (and weeds). Several mid to high eighty-degree days pushed corn from V3 last week to V5. At V5, all of the embryonic leaves and ears have been initiated in the corn plant, and its growing point (meristem) will soon be above ground. The warm weather also pushed the soy crop, last week a no-till soy field at VE has reached nearly V1 with the first set of trifoliates unfurling. I would be remiss if I did not share that the great growing weather also benefitted weeds as well. Several species, especially waterhemp are matching the crops quickened growth. In this region, most planting has finished and farmers are taking advantage of the rain free forecast to harvest the first hay cutting.
Over the years I have made numerous trips from Grundy County to the University of Illinois campus. My most frequent route includes a stretch of Route 47 straight south to Interstate 74. Yesterday I made the trip and wanted to share my windshield observations. I noted several agronomy practices that seem to be picking up in frequency, they include sidedressing corn with liquid nitrogen, no-tilling soy into a standing cereal rye cover crop, and a growing number of winter wheat acres in rotation. It will be interesting to follow these fields and practices as the growing season progresses.

Another good week for field work in the region. Substantial progress was made in both corn and soy planting. Several eighty degree days helped spur growth in planted crops; however, I noted no-till soy fields, especially soy planted into heavy corn residue, were lagging in emergence and development, likely due to cooler soils. It is generally suggested with soybeans that cotyledons provide the needs of the plant during emergence to almost V1 (first trifoliate) stage. After V1, the photosynthesis of the vegetative plant will sustain itself. Early planted corn in the region has reached V4. Underground, the seminal root system has been joined by the nodal root system. The nodal root system of the corn plant is initiated at VE and becomes the major supplier of nutrients and water to the plant by V6.

Scouting fields at emergence and early vegetative stages is helpful in evaluating planter (and operator) performance by observing uniformity of plant stands, spacing and overall emergence. Additional notes can be taken on early season diseases, compaction or poorly drained areas in a field, and early season performance of soil-applied herbicides.

Soft red winter wheat has reached anthesis or flowering. For those considering a fungicide application to control Head Scab, this is a recommended window of application. In forage crops, alfalfa has started to flower, an indicator for harvest consideration (depending upon your goal of quality or quantity) when a favorable weather window permits.

A favorable week for field work in the region. Many corn and soy fields were planted and operations continue in the area. Earlier planted corn appears to be emerging with a slight advantage to soy. This week we will be starting the aphid suction collection trap in Morris, part of the Suction Trap Network that will be monitored through October. This trapping program is led by Dr. Doris Lagos-Kutz, Illinois Natural History Survey-Prairie Research Institute. The program generates data on aphids and other beneficial and pest insects across multiple states. (https://suctiontrapnetwork.org/)
While corn and soy crops are waiting for consistently warm weather to expedite growth, several weed species have flowered or grown rapidly in untreated or unworked fields. They include the yellow flowered winter annual Butterweed, and the early emerging summer annual Giant Ragweed.

I’m looking forward to another growing season and crop reporting in Northeast Illinois. April and May precipitation has slowed planting progress compared with other regions of Illinois. I’m estimating almost as much seed is still in the bag as is in the ground. On suitable days for planting, reports received suggest local farmers actively planted both soybeans and corn. The practice of planting soybeans ahead of corn acres has been adopted by many. Whether corn or soybeans, I was impressed by the acreage planted in a limited time frame. Despite planting date, low accumulations of GDDs have slowed crop emergence.

With limited emerged crops, we will highlight insect pests found in alfalfa. While sweeping alfalfa, we netted alfalfa weevil larvae, aphids and bean leaf beetles. We will continue to monitor leaf feeding in the alfalfa crop to determine whether a management threshold is reached.