Darby Danzl
Regional Technical Agronomist
darby.danzl@ilsoy.org

Darby Danzl
Regional Technical Agronomist
darby.danzl@ilsoy.org

Darby Danzl UPDATES

Region 5 | August 8, 2025 | Shelby/Macon/McLean

Darby Danzl
darby.danzl@ilsoy.org

Caption: Foliar and root symptoms of red crown rot in Shelby/Macon County.
Caption: Grasshopper feeding on a corn leaf in McLean County.
SYNOPSIS

The beans are TALL as they enter the mid-R stages of growth. All fields I scouted this week were between R3 and R5 (beginning pod to beginning seed), depending on planting date. Corn is currently around the R3 to R4 (milk to dough) stage.

Stephanie and I saw some red crown rot in soybean fields around the Shelby/Macon County area, specifically in fields where she found it two years ago. The disease shows very visible symptoms, including yellowing and browning between the leaf veins (interveinal necrosis) as well as reddish discoloration at the base of the plant near the root. When you look at the root of a soybean plant infected with red crown rot, you’ll often notice white fungal growth (mycelia). Warm soil temperatures (77–86°F) are ideal for this fungus to thrive, so the recent warm days have likely contributed to its presence.

WHICH OF THE FOLLOWING BEST DESCRIBES CURRENT CONDITIONS IN THIS COUNTY?
Mildly Dry (soil is drier than normal, plant growth may have slowed)
IF CONDITIONS ARE ON THE DRY END, WHICH OF THE FOLLOWING US DROUGHT MONITOR CATEGORIES BEST FIT CURRENT CONDITIONS
Near Normal (Dnada)
WEATHER

High 80s low 90s this week and looks like next week as well.

PRECIPITATION

We’re starting to get a little dry, as it’s been a while since we had a good rain. It’s not too concerning for soil moisture levels just yet, though.

SOYBEAN GROWTH STAGE

R3-R5, Double crop beans in McLean county are at V4.

CORN GROWTH STAGE

R3-R4

INSECTS

I set up sticky traps last Wednesday to monitor for corn rootworm beetles in a cornfield in McLean County, but I didn’t see any on the traps when I replaced them this Wednesday. I did see some grasshopper feeding near one of the traps.

DISEASES

Red crown rot has appeared in some fields in Shelby and McLean counties. I’m still seeing some southern rust, along with corn leaf miner and Goss’s wilt, but mostly as isolated cases within the field.