Illinois Crop Update – August 22, 2025

Steve Brand– Commercial Agriculture Specialist

DeKalb County

Soil Condition: Near Normal

After a wet couple of weeks up north we are all but back to normal precipitation levels for the season. Most areas across northern IL saw anywhere from 1-4 inches of rain depending on how many storms hit over the past weekend and have primed plants to finish strong through ear and pod fill. Disease has become much more prevalent as the rain has opened up and temperatures have dropped from the 90s.

Corn is entering dent or R5 across the region with varying degrees of how far along kernels are, depending on planting date. Tar spot is usually the big fear, disease-wise, but this season early winds from the south brought up southern rust. Generally, not a concern for robbing yields this disease does look like it may lower yields slightly on fields that were not sprayed with fungicides this season. Since southern does not overwinter in the north, inoculum is not an issue for next season. Tar spot is beginning to move into the upper canopies, but it is not recommended to spray this late in the season due to lack of ROI from the sprays. Another issue I have seen in multiple fields has been some tip back on corn ears. Generally environmental conditions can cause poor pollination. The extreme heat waves and droughts in different regions across northern Illinois would be my guess to why we are seeing this across the region.

Soybeans continue to look great. With how tall they have grown later into the season I have seen some slight lodging in areas after the severe storms rolled through over the weekend. Disease continues to be a non-issue in most fields. I found white mold for the first time this season in some lodged beans, but I again expect the disease to be low based on the drought and high temperatures we had at soybean flowering. Overall beans look to be headed to some great yields.

 

 

 

Russ Higgins – Commercial Agriculture Educator

Grundy County

Soil Conditions: Near Normal

Precipitation, including fields receiving substantial rainfall totals this recent week in Northeast Illinois. Isolated corn fields showing significant disease pressure but also nearing maturity. In the R5 stage the corn kernel has “soft” and “hard” starch. The transition or hardening of the soft starch into the hard starch begins at the top of the kernel and progresses to the tip. The progress of this process is visible as the “milk line” of the kernel. Corn is approximately 55% moisture at the beginning of R5 and 30 – 35% moisture at the conclusion. Generally corn plants are expected to complete the R5 stage in about 30 days accumulating dry matter content. The soy crop is nearing the R6 stage, R6 or full seed plants have a green seed that fills the pod at 1 of the top 4 nodes on the main stem of the soy plant. Once reaching R6 new leaf growth ceases and lower leaves start to yellow and drop off. We are encouraging growers, especially with past history of the disease, to be wary of white mold in their soy fields.

For those attending the Farm Progress Show next week, visit Illinois Extension at the University of Illinois College of ACES tent on West Progress Avenue.

 

 

 

Reagan Tibbs  – Commercial Agriculture Educator

Logan County

Soil Condition: Near Normal

Rain showers earlier in the week brought a good amount of moisture to the area, giving some fields a much-needed boost. Much of the corn across Logan County has entered the R5 dent stage, with some fields right behind in the R4 dough stage. Much of the same can be said for soybeans, with most fields across the County in the R5 stage as well. The end of the growing season is getting closer, and some plants are starting to show signs of approaching their full maturity.

 

Doug Gucker – Local Food Systems and Small Farms Educator

Dewitt, Macon, and Piatt County

Soil Conditions: Mildly Dry (soil is drier than normal, plant growth may have slowed)

Soybeans in many fields are reaching the R6, Full Seed stage. Late-season insect and disease pests are beginning to show in some soybean fields. A few soybean fields are nearing R7, Beginning Maturity stage.
Corn is in the R5, Dent stage. Corn fields that are experiencing moderate drought are showing uneven crop maturity.

 

 

 

Talon Becker  – Commercial Agriculture Specialist

Champaign County

Soil Condition: Near Normal

Champaign County received some needed rains this past week, totaling about 1-1.5″ across the county. As I surveyed the southern half of the county on 8/20, surface soils in most fields were still slightly wet from the most recent storm the morning prior, with the southwest corner of the county being a bit drier than the rest of the survey area. Corn fields surveyed were generally in the late R4 “dough” to R5 “dent” growth stages. The severity of observed tip dieback ranged from minimal to 2+ inches across the survey area.

Full-season soybeans were generally somewhere in the R6 “full seed” growth stage, with just a few fields I saw starting to drop leaves and enter the R7 “beginning maturity” stage, at least in parts of the field. I came across a couple double-crop soybean fields during my survey, both of which were just entering the R3 “beginning pod” growth stage. One of these fields featured a placard from the IL STAR Program, which aims to connect farmers utilizing conservation practices on their land with end-users of the produced grain that are willing to pay premiums that support those farmers and practices.

 

 

 

Dane Hunter  – Commercial Agriculture Specialist

Marion County

Soil Condition: Moderately Dry (soil is dry, plants may be browning or stressed, water bodies are low)

Conditions are dry. We haven’t had significant precipitation since mid-July, and while there is still some subsoil moisture, our high clay content doesn’t ensure plant availability. After the heat of the last few weeks, corn has been looking a little stressed, and leaves are firing in areas of thin soil or ponding earlier in the season. Corn is starting to dent.
Most first crop soybeans are at R4-R5, depending on planting date. Late planted and double crop beans are still at R2-R3 and could benefit from late-season precipitation like we’ve had the last few years, as a result of inland hurricanes blowing up from the Gulf.

Figure 15: Ear of corn entering R5, kernels starting to dent. end of ear showing aborted early, likely due to stress during pollination.
Alt text: ear of corn entering R5, kernels starting to dent. end of ear showing aborted early