The earlier heat and lack of rain over the last 4 to 5 weeks brought an earlier senescence for both corn and soybeans. Some areas received a few tenths with the last storm that came through with the cold front, but it was too little, too late. Corn is just about at black layer, with some testing at 19.5 to 24% moisture. Many in the surrounding counties are getting ready to start harvest. The 3.5 maturity soybeans are just starting to turn R7, but the 4.0s are mostly green or at R6.

Cooler temperatures have arrived this fall (late summer, really) as we move through the waiting period of the growing season for corn and soybeans. Temperature averages in the 70s and low 80s have brought much relief after a very hot stretch across northern Illinois. Nearly every corner of Illinois north of I-80 is at normal rain and water levels, while downstate areas are beginning to enter into a slight drought, and plants continue to work through ear and pod fill. I have noticed diseases starting to really ramp up with temperatures dropping and heavy dews every morning.

Corn is still green and starting to fire as it reaches maturity. Most fields I visited were full dent, with the milk line in the ear around 50%—maybe a little further along in some places (west of DeKalb was scouted this week). With the cooler temperatures and daily dews, tar spot and ear mold in particular have taken off in corn. Every field I visited had lesions well into the upper canopy, with lower leaves turning brown, necrotic, and dying. The upper third of plants above the ear are still green, so ear fill is still occurring even as the bottom dies out. Ears are starting to see small amounts of mold on the ear tips as well. Black layer is most likely 10–14 days away, based on the milk line and cooler temperatures.

Soybeans are still mostly green, with select fields either planted early or of an earlier variety starting to turn and enter senescence. For as disease-free as we were early in the season, SDS has flared up across many fields and is starting to take off in hot pockets. This year is a very important year to scout your fields if you see SDS symptoms. Red crown rot is a new disease seen in the area that has the exact same foliar symptoms. The key characteristic to look for is a bright red color on the soybean stem just above the soil layer, and in some cases, red spore balls called perithecia. If you find what you think could be red crown rot, please contact your local extension office so we can work with you to get that sample tested for identification.

Other than that, we are moving along and marching toward harvest. Northwest Illinois and Joliet are a bit ahead of the DeKalb area in terms of maturity, and harvest will be right around the corner!

The storms that moved through the area in the evening of 9/3 did bring some needed rain, but rainfall totals appeared to be variable across Douglas County based on field soil conditions during my survey. This is backed up by the difference in registered rainfall totals between the Illinois State Water Survey monitoring stations in Bondville and Champaign, which recorded about 0.4″ and 1″ of rain, respectively, despite the stations being less than 10 miles from each other. In Douglas County, it appeared much of that rain missed the southwest part of the county.

Despite the dry conditions, corn and soybean crops are still looking good overall. Corn fields were generally in the early to mid-R5 (“dent”) stage. Tip fill was generally good, although ear size did vary a decent amount from field to field. Early-maturity soybeans are starting to hit R7 (“beginning maturity”) in areas of those fields, but there are still plenty of later-maturity soybean fields in the R6 (“full seed”) stage with a full green canopy. It seems harvest is still at least a couple of weeks out for most in Douglas County.

The past two weeks have seen late-season leaf diseases appear in area fields: tar spot, common rust, southern rust, gray leaf spot, and others. A few farmers have taken out end rows in corn fields. In moderate drought areas, corn fields have fired up to the ear in the drier parts of the fields. Corn fields are in the dent stage (R5), and a few fields are in the mature stage (R6).

Soybean fields are turning yellow, reaching the R7 (beginning maturity) stage, with early-maturity soybean fields at or nearly at the R8 (full maturity) stage.

To put it simply, it’s a race to the finish in corn. Tar spot and southern rust are really taking over the plant as we start September. The cool temps, coupled with fungicide residuals wearing off, are the perfect recipe for disease. In beans, you’re just starting to see some early maturities turn. Over the last couple of weeks, I have started to see sudden death and white mold, with sudden death seeming more prevalent. The rain in mid-August really made me more optimistic about the bean crop, but if we could catch another rain in the next 10 days, that would be ideal.

It feels very fall-like with low humidity and temperatures in the low 80s. The crop is proceeding well, and some corn and soybean harvest will begin next week, mainly March corn and late group 2 soybeans.

Conditions remain dry. We haven’t had significant rainfall since mid-July, and while some subsoil moisture is present, the area’s high clay content limits plant availability. After several weeks of heat, corn is showing stress, with leaves firing in areas of thin soil or earlier-season ponding. Corn is beginning to dent.

Most first-crop soybeans are in the R4 to R5 stages, depending on planting date. Later-planted and double-crop beans are still in R2 to R3 and could benefit from late-season rainfall, similar to the inland hurricanes from the Gulf that have boosted yields in recent years.

After a wet couple of weeks in Northern Illinois, precipitation levels are nearly back to normal for the season. Most areas received 1 to 4 inches of rain over the past weekend, depending on storm tracks, which has primed plants to finish strong through ear and pod fill. Disease has become more prevalent as rainfall increased and temperatures dropped from the 90s.

Corn across the region is entering the dent, or R5, stage, with kernel development varying by planting date. Tar spot is usually the primary concern, but early southern winds this season brought in southern rust. While southern rust generally does not cause major yield loss, it may slightly reduce yields in fields that were not treated with fungicide. Because the disease does not overwinter in northern climates, it is not expected to be an issue next season. Tar spot is moving into upper canopies, but spraying this late is not recommended due to limited return on investment. Another issue observed in multiple fields is tip-back on corn ears, likely caused by poor pollination during extreme heat and drought earlier in the season.

Soybeans continue to look strong. With their height later into the season, some fields experienced slight lodging after severe storms over the weekend. Disease pressure remains low overall. White mold was found for the first time this season in some lodged beans, but incidence is expected to remain low due to drought and high temperatures during flowering. Overall, soybean yield potential looks very good.

Rain showers earlier this week brought much-needed moisture to the area, giving some fields a boost. Most of the corn in Logan County has entered the R5, or dent, stage, with some fields still in R4, or dough. Soybeans are showing similar progress, with most fields in the R5 stage. The growing season is nearing its end, and some plants are beginning to show signs of full maturity.

Champaign County received much-needed rain this past week, totaling about 1 to 1.5 inches. During a survey of the southern half of the county on Aug. 20, surface soils in most fields were still slightly wet from the previous morning’s storm, with the southwest corner a bit drier than the rest of the area. Corn fields surveyed were generally in the late R4, or dough, to R5, or dent, growth stages. The severity of tip dieback ranged from minimal to more than 2 inches across the area.

Full-season soybeans were generally in the R6, or full seed, stage, with a few fields beginning to drop leaves and enter R7, or beginning maturity, at least in parts of the field. I also came across a couple of double-crop soybean fields, both just entering the R3, or beginning pod, stage. One of these fields featured a placard from the Illinois STAR Program, which connects farmers using conservation practices with end-users willing to pay premiums that support those practices.