It’s another hot week upon us as a heat dome settles over the Midwest. July so far has brought 3.5 to 5 inches of rain, depending on the area, excluding Will County, which remains in a somewhat severe drought. Northwest Illinois is on pace with historical averages and enjoying a great growing season. South of Chicago and some suburban counties are drier than normal and continue to be in either a D1 or D2 drought. Corn planted on April 25 is likely around 1,500–1,600 growing degree units for the season.

Corn is mostly tasseled across the region, ranging from R1 to R2 (blister stage) and looking very healthy. With recent rains, disease has finally arrived across northern Illinois. I confirmed tar spot in DeKalb, Kane, McHenry, and Lake counties this week, with strong suspicions it is also present in DuPage and nearby counties. All plants I scouted had one or two lesions on the leaf below the ear leaf. At this point in the season, most fungicides have already been applied and should protect the crop through harvest. Scouting will help determine if additional sprays are needed, though anything after R3 is generally not recommended. Gray leaf spot has also been working its way up corn plants.

Soybeans are progressing well. Disease pressure is low, and they are moving into R4, with 3/4-inch pods. While we’re still seeing some stunting in northern Illinois from early drought and delayed emergence, overall soybean health looks good. Not much else to report, as pods are setting and filling.