Harvest has begun, and very dry conditions are moving back in. Fire risk is becoming an issue as harvest picks up speed. Late-planted corn is in real trouble, and all crops are ripening fast.

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.

Onward! Corn and soybeans both are marching toward season’s end. Fields in my area are really starting to have that “late-season” look this week. Much cooler temperatures arrived on 9/3, and daytime highs in the mid-60s really made it feel like fall. Walking through corn, I’ve noticed a significant uptick in foliar disease across the board. Some fields are showing quite a bit of GLS, and others NCLB, on and above the ear. Most notable to me, however, was the amount of late tar spot I’ve seen. Natural leaf firing from the bottom is a normal part of filling out the ear, but there’s a difference between that and earlier-than-normal leaf death from the culmination of tar spot plus two to three other leaf diseases. I’ve been in some fields that really need to be watched closely as harvest approaches, and I hope they don’t get a significant wind event. Stalks in the worst fields are already weak and prone to breaking just by crossing rows. Most ears look good and are well into dent stage, with milk lines ranging from ¼ to ¾. I expect black layer to be a couple of weeks away yet in most fields.

Soybeans are mostly into the full seed stage, and you can see the leaves beginning to yellow. Early-maturity fields are into leaf drop now, and some are probably 50–60% dropped. Pockets of Sudden Death Syndrome are beginning to show up a little more, but it does not appear to be as widespread as in some years. I have not seen any red crown rot in my area. Cooler overnight temperatures have led to some very heavy dews in the mornings. Lingering moisture on green leaves, plus a blue sky and sunshine, has caused a fair amount of sunscald on the bean leaves, but at this point I would not expect that to have any significant impact on the plant.

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.

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 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.