The past three days featured almost unbearable 90 degree plus days, compounding extreme dry or drought conditions for the 2024 crop. It ended with a 1 inch plus rainfall for some in the Northeast on Tuesday night. Prior to the precipitation, both corn and soy were demonstrating heat stress. One of the oddities found while scouting our now mostly R6 (full seed) soy was Thistle Caterpillar. The Lepidoptera adult is also known as the Painted Lady Butterfly. Thistle caterpillars are not known to overwinter in Illinois but migrate north annually from the southern US and Mexico. The caterpillars form webs by tying leaves together with silk creating a protected area for them to feed. Almost always considered a sporadic pest, it rarely causes enough defoliation to warrant treatment.
Today, Dr. Boris Camiletti, Plant pathologist with the University of Illinois shared his observations on the 2024 growing season from a plant disease standpoint to a gathering of Northeastern Illinois farmers. Diseased crop samples brought to the meeting were identified as Tar Spot, Northern Corn Leaf Blight, Gray Leaf Spot, Southern Rust and White Mold. In addition, ear rots Fusarium and Penicillium were found. Dr. Camilletti encouraged growers to continue scouting practices to aid in management decisions, make use of the Illinois Plant Clinic, and be on the watch for Red Crown Rot in soy that it is progressing its way north in the state.

Well, corn sweat is the buzzword of the week and it’s been hot and humid. We’re seeing some tar spot and other disease pressure popping up in fields. There’s a mix of weed pressure across the county with mild insect presence. Corn is R3-R5 depending on planting date and soybeans are R3/R4 again pending planting date. Overall, crops are looking good.

The corn and soybean crop across Ford county is progressing well, with most fields reaching the later stages of grain fill. The drawn out planting season is still apparent, with a range of crop maturity observed across the county. Some bean fields are beginning to drop leaves (late R6) while others are still filling pods (R5). Of corn fields surveyed, most were in the early to mid dent (R5) stage, but I found a few fields still in dough (R4). Soybeans fields visited showed minimal signs of disease. This was also true for most corn fields, although a couple fields I visited in the northern part of the county were showing signs of tar spot (confirmed by the Plant Clinic), among other foliar diseases. Soil moisture conditions in fields surveyed were good, with the crop showing little to no moisture stress despite base temps in the 90s during my survey.

Diseases should continue to be monitored for progression. The temperatures next week will most likely slow tar spot advancement. Note weed escapes to determine if adjustments need to be made for 2025. The hope for next week is maturing crops and not premature death.

We really could use a rain for the later planted soybeans as well as some corn. Despite the dryness, some tar spot and southern rust has started to show up on late-planted corn. European corn borer was also found in late planted corn (R3). Overall, soybeans are progressing well, but have unfortunately found red crown rot as well as SDS. Frogeye leafspot is just starting to show up.

Crop conditions continue to look good around Logan, Menard, and Sangamon counties. While there has not been much rain in the last week, cooler temperatures have ensured plants are not under heat stress as we approach maturity. There have not been any significant reports of any diseases across the area, though some isolated cases may be present. Many local producers have also completed their third hay cutting for the year. With the cooler temperatures and rain over the last couple of weeks, many fields are already starting to grow back nicely and could see a fourth cutting.

It’s a good time to scout for fall armyworms in grass hay, pasture, alfalfa, etc; a quick survey of my colleagues in the states to our south indicated it is a big year for this insect (though they were unanimous that it was not as bad as in 2021, the last time we saw widespread damage in Illinois).

Recent precipitation and current cool conditions are favorable for both corn and soy crop grain fill. The extended forecast is dry and warmer, which could expedite the grain fill window. For crops on some lighter soils in the Northeast, recent rains appear to have arrived late. Corn in sandy and soils with poor water holding capacity senesced quickly over the recent week. In field areas that flooded or have decreased plant populations due to environmental conditions, I’m finding grass weeds happily filling the void. One species in particular, Fall panicum, seems to be having an exceptional year. This summer annual can reach seven feet in height and is recognized by appearing to be growing in a zig-zag pattern caused by growth bending at the nodes. The seedhead is easily identifiable, resulting in a wide spreading panicle when mature.
For those in Grundy County and surrounding areas, Illinois Extension and the Kendall-Grundy Farm Bureau are partnering to host University of Illinois plant pathologist Dr. Boris Camiletti on Wednesday, August 28th at 1:30 pm at the Kendall-Grundy Farm Bureau building. Dr. Camiletti will lead a discussion on his research projects and share experiences in his first Illinois growing season. Producers, landowners and agronomists are encouraged to bring plant samples the afternoon of the meeting for discussion or identification purposes. Anyone is welcome to attend, the Kendall-Grundy Farm Bureau building is located at 4000 N. Division street in Morris, Illinois.

Cool temperatures lately should help grain fill. Moisture in CIL has been plentiful. Disease is starting to show especially what appears to be SDS in soybeans. I have seen several diseases in corn, but so far nothing of major concern. Tar Spot could be one to watch as it can rapidly evolve. I have heard of some 2nd fungicides being applied to the later planted corn to help it finish. The low areas of fields are starting to show up again, likely due to leached N or compaction and thus lacking root development.

Following the storms that came through the areas late last week, soils have plenty of moisture in the northern Vermilion County area. There was standing water visible in some small ponds in headlands, but these were few and far between. Crop health looked good, overall, but corn fields are starting to show some areas with late-season nitrogen stress with variable ear size and tip fill. Signs of what appears to be Physoderma stalk rot (visual identification only) were also present in a number of corn fields (https://cropprotectionnetwork.org/encyclopedia/physoderma-stalk-rot-of-corn). In fields surveyed, corn was at late R4 (dough) to early R5 (dent). Soybeans generally ranged from R4 (full pod) to R5 (beginning seed), with a few fields edging closer to R6 (full seed). Weed control was variable. Most corn fields I walked into were relatively clean, but soybean fields showed a range of weed control efficacy.