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.

Southern Illinois experienced planting delays this spring due to excessive rainfall, which pushed field activities into late May and early June. Despite these challenges, soybeans are currently at the R2 (full bloom) growth stage, and the corn that was planted has also reached reproductive stages. One field I scouted showed significant defoliation caused by insect pressure from bean leaf beetle, Dectes stem borer, and striped blister beetle, all of which can continue to impact soybean growth and development if not properly managed. At the R2 stage, the defoliation threshold for bean leaf beetle is 15–20%, and for blister beetle, it is 15%. At these levels, an insecticide application is warranted to prevent economic yield loss.

It has finally stopped raining. Even though we were supposed to have a cool down, it has continued to be very hot and humid. The fungicide on corn appears to be holding fungal diseases below the ear. I did see some Southern rust on the end rows of corn, but not bad as you go into the field. There are obvious disease differences on different hybrids. Corn is almost at full dent. Soybean disease symptoms of SDS are starting to show. Red crown rot has not been a major issue in Montgomery Co., but this year, this disease has unfortunately made its debut and is here to stay. Soybeans are at R4 growth stage.

Despite the seasonally warm temperatures during the last week, many crops across Logan County benefited from a rain shower early in the week. Most of the county saw 1 to 2 inches of rain, which will undoubtedly help crop growth. Many corn fields are moving into the R5 “dent” stage, with not many lagging behind the leaders. Much the same can be said for soybeans, with most fields in the R5 seed stage.

Soil moisture conditions across the three counties vary from wet to moderate drought. Rainfall has been quite variable across this area.

Soybeans planted in April are in the R5 (full pod) stage. The April-planted corn is in the R4 or R5 stage. Crops look good even in the dry areas at this time.

Weed control has been very good. I have noticed that conventionally farmed soybean fields with weed issues typically only have a problem with one weed group—either the Amaranthus family or velvetleaf (Abutilon theophrasti). Grassy weeds have not been an issue across the area in conventionally farmed fields.

This week, Dr. Giovani Preza Fontes, assistant professor and agronomy extension specialist at the University of Illinois, visited the Grundy-Kendall County area and met with area producers, where he shared expectations for both state and local yields. Farmers were provided with recent weather data and were encouraged to take kernel and population counts to determine yield estimates in their own fields.

The pattern of variable rainfall and pop-up isolated thunderstorms discussed was demonstrated that day, with rainfall ranging from 0 to 2-plus inches within a 40-mile radius. Most corn is at the R5 stage, and the likelihood of a return on investment from a fungicide treatment (or additional treatment) at this stage is unlikely. That said, scouting corn that did not receive a fungicide treatment in some fields is like taking an introductory course in plant pathology. Symptoms of tar spot, northern corn leaf blight, gray leaf spot, and southern rust can all be found.

Recent environmental conditions have been especially favorable for the development and spread of southern rust. All leaf diseases are reducing photosynthetic leaf tissue that would aid in grain fill.