Illinois Crop Update – August 1, 2025
Emily Hansen – Commercial Agriculture Educator
LaSalle County
Soil Conditions: Mildly Wet (soil is wetter than normal, local vegetation is healthy)
The heat and humidity has finally broken today after what feels like a very miserable few weeks. Over the past week rainfall in LaSalle, Bureau, Marshall, and Putnam counties has been sporadic, with some areas seeing nearly 6 inches and others seeing less than an inch. Crops in areas that received less rainfall are still looking a little heat stressed. Overall, though, most crops are looking healthy, but the increased rainfall has finally brought disease to my four-county unit. Tar spot has now been officially reported in all but Putnam County, though I suspect the disease is also present there as well. Most growers have finished applying fungicide, but crops are progressing to the point where it is no longer recommended. Corn has reached R3 (milk) and soy R5 (beginning seed). Double-cropped soybean is at V2/3. Pest pressure is low overall – rootworm, bean leaf beetle, and Japanese beetle have been observed in soy fields but no significant damage has been reported. One soy field scouted this week showed signs of sudden death syndrome. The damage was isolated to a fairly small area of one field (see images below).
Russ Higgins – Commercial Agriculture Educator
Grundy County
Soil Conditions: Near Normal
And just like that, conversations on drought have ended (for now) in Northeast Illinois. Cumulative precipitation exceeded four inches in areas last week. While the rain is welcomed, earlier planted corn that pollinated during the dry stretch resulted in kernel abortion. More favorable growing conditions should enhance grain fill and benefit longer maturity and later planted corn. Dr. Boris Camiletti posted a Red Crown Rot Progressing in Illinois Bulletin article on July 28th. The disease has been confirmed as far north as Livingston and Kankakee Counties. Growers in northeast Illinois are encouraged to be aware of SDS-like foliar symptoms in soybean and are encouraged to submit samples to the plant clinic for confirmation. Illinois Extension and the Kendall-Grundy Farm Bureau are hosting a 2025 Crop Development Update meeting on August 12th at 11250 N Church Road, Minooka. At the 1:30 pm meeting Dr. Giovani Preza-Fontes, University of Illinois Agronomy Extension Specialist, will share expectations for a growing season that has been filled with temperature and precipitation extremes. In addition, Steve Brand, Northern Illinois Extension specialist will share insights into plant diseases found across northern Illinois. The meeting is open to the public.
Talon Becker – Commercial Agriculture Specialist
Vermilion County
Soil Conditions: Near Normal
Frequent rains over the past week have maintained adequate soil moisture levels in northern Vermilion County. As I conducted my survey in the morning of 7/31, light rains were falling once again. Despite the relatively wet conditions for this time of year, disease pressure was still low in the corn and soybean fields visited. In corn, the more common site was the tell-tale “inverted V” chlorosis/necrosis patterns showing up in the lower canopy in areas of fields where nitrogen is limiting and the plant is needing to remobilize that nitrogen to put towards grain fill. Most corn fields surveyed were generally in the R3 “milk” stage, with some still in late R2 “blister” stage. Soybeans were generally in the R3 “beginning pod” to R4 “full pod” stages, although a couple fields surveyed were nearing R5 “beginning seed”.
