Illinois Crop Update – July 21, 2023
*Edited July 24, 2023 to include report from R. Higgins.
Russ Higgins – Extension Commercial Ag Educator
Grundy County
Soil Conditions: Mildly Dry (soil is drier than normal, plant growth may have slowed)
Wheat harvest has mostly wrapped up in NE Illinois. This week, fungicide applications started in earnest, and I observed fields sprayed by plane, helicopter, ground rigs and a drone! Many growers simply include a fungicide application in their management plan; however, we still encourage scouting to determine disease pressure before committing to a fungicide application. Being aware of requirements and favorable conditions for certain diseases. Examples include northern corn leaf blight and tar spot; both require extended periods of leaf wetness (6 – 7 hours) for establishment. With recent rainfall many have noted early morning mist settling over some fields, facilitating the leaf wetness requirement. For those still considering an application, the Fungicide Efficacy Guides (from Land Grant Universities) have been updated for 2023 and can be accessed at this link.
Will the dry weather in June and resulting shorter corn plants have an effect on final yield? One of the things I have noted scouting some corn fields is the amount of light reaching the ground. In my experience during good growing seasons very little light reaches the ground at R1. As the picture demonstrates, that is not the case in all fields this year.
Figure 1: Early morning mist – Grundy County, July 18, 2023.
Figure 2: Mid-day light interception in corn – Grundy County, July 20, 2023.
Doug Gucker – Extension Local Food Systems and Small Farms Educator
Macon County
Soil Conditions: Mildly Dry (soil is drier than normal, plant growth may have slowed)
During my 40-mile crop survey across DeWitt, Macon and Piatt counties, I noticed several things. First, the very spotty nature of the recent rains with water standing in a field and a mile away it was powder dry. Second, it seems that residual weed control is not lasting long enough in some 30-inch row soybeans. I saw applicators in two fields spraying to control amaranth in 30-inch soybeans and other fields that had been sprayed in the past week. Third, the effects of the violent storms in late June that crossed the area are particularly evident in corn fields showing tattered leaves or elbowed stalks. Soybeans for the most part are in the R3 growth stage with early planted fields approaching the R4 stage. Corn field growth stages varying from R2 (blister) to R3 (milk).
Figure 3: Soybeans are in the R3 growth stage with this field almost in R4.
Figure 4: Most corn fields are in either the R2 or R3 growth stage.
Figure 5: Amaranth weed escapes showing up in some 30-inch row soybeans with post-emergent applications being made.
Talon Becker – Extension Commercial Agriculture Educator
Champaign County
Soil Conditions: Mildly Dry (soil is drier than normal, plant growth may have slowed)
This week, I visited fields in central Champaign County. With much of the recently forecasted rain missing the area, soils are starting to dry up again. Digging down in a few fields, there is still some moisture present a few inches below the surface, but that too is starting to dry. Plants do not looked stress at this point in time, but that could change quickly with a warm week ahead of us and minimal chances for rain in the current forecast. The vast majority of corn fields I visited had finished pollination and were generally at blister (R2) or milk (R3) stages. Soybeans were generally at beginning pod (R3) to full pod (R4). Weed control was variable, with most pressure coming from waterhemp, and a few morning glories here and there. From the road, many soybean fields still look rather clean, but waterhemp pushing through the canopy is also starting to become a more common sight in the area.
Figure 6: Waterhemp pushing through soybean canopy – Champaign County, July 21, 2023
Figure 7: Corn at milk stage (R3) – Champaign County, July 21, 2023