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The Bulletin

Illinois Crops Update 8/12/2022

Chelsea Harbach

Department of Crop Sciences
University of Illinois

August 12, 2022
Recommended citation format: Harbach, C.. "Illinois Crops Update 8/12/2022." Department of Crop Sciences, University of Illinois, August 12, 2022. Permalink

Each week, I put out a request to crops educators and specialists from the University of Illinois to compile an update to share with the entire state. We hope you find this information useful. If you have any questions or suggestions about the format or any feedback in general about these updates, please email me (

Trent Ford, Illinois State Climatologist, Illinois State Water Survey

Following a cold front that moved through mid-week, we saw a drop in both temperatures and humidity. Several spots in northern and central Illinois reached into the low to mid 50s on Thursday morning and Friday morning, including 51 degrees in Dwight and 53 in Macomb. This follows a July that was about half a degree warmer than normal statewide. Northwest Illinois saw quite a bit of rain this past week with totals ranging from 3 to 6 inches in Jo Daviess, Stephenson, and Carroll Counties. However, this week continued a relatively dry period for parts of western and central Illinois. Parts of Hancock, Henderson, Warren, and McDonough Counties in western Illinois have been 3 to 4 inches drier than normal since June 1st, and the US Drought Monitor expanded moderate drought in that part of the state this week. Meanwhile, the drier weather was welcome in parts of south-central Illinois that have been 5 to 8 inches wetter than normal since July 1st. In fact, last month was the 2nd wettest July on record in Edwards, Richland, Wayne, Madison, and St. Clair Counties.

Looking ahead: there will be a brief warm up this weekend with highs in the mid to upper 80s, followed by a prolonged period of cooler than normal weather. Expect highs next week in the low 80s and even upper 70s as far south as Carbondale. At the same time, most of the state is forecasted to pick up less than a quarter of an inch of rain the next 7 days. The outlook for the third week of August is similar, with below normal temperatures likely through the 21st, while above normal precipitation is favored as we move closer to the end of the month.

Talon Becker, Commercial Ag Extension Educator, Southern IL

The rains that have come over the past couple weeks have been a mixed bag for farmers in the south-central IL region. Farmers whose fields were on the dry side have seen their soil moisture recover to closer to optimal levels, while farmers in the counties between I-70 and I-64, in most cases, have received more rain than they would have liked. Waterlogged soils in these areas may provide a favorable environment for certain diseases, particularly soil-borne soybean pathogens, to take hold and cause some yield loss.

Phillip Alberti, Commercial Ag Extension Educator, Northern IL

The impacts from the storms this past weekend are still evident across parts of Stephenson and Jo Daviess county where accumulations exceeded a whopping 9+ inches in some areas over the two-day period. Research shows that the impacts of flooding are dependent on crop growth stage, current and future weather, the amount of time the plants are submerged, and the amount of residue remaining on the plants. While damage is often minimal if flooding is short-term (under 48 hours), corn (R3-R4) and soybeans (R4-R5) are still underwater in some areas. Flooding for more than 4 days greatly reduces the chances of survival. In areas of long-term ponding, lingering impacts including potential lodging and ear mold development should be evaluated when you are able to do so safely. Moderate, dry conditions over the next week should help to mitigate some of these impacts, but unfortunately, assessment of the true impact of these storms will not be possible until after the water recedes.

Chelsea Harbach, Commercial Ag Extension Educator, Northwest IL

I spent the last week up in my home county of JoDaviess County, so my observations come from the far NW corner of Illinois this week. Apologies in advance that this will be pretty similar to Phillip’s update. But we were shocked to receive up to 13 inches of rain in some parts of Stephenson and JoDaviess Counties this past Sunday/Monday (just in time to let planes finish flying on fungicides at the end of the week prior). These applications will be quite timely, as the likelihood of disease development with these rain events and moderate temperatures goes up. I received a couple more reports of tar spot incidence in the past week, one in Fulton County and one in Hamilton County. Furthermore, Southern rust on corn is starting to move up into the southern tip of Illinois. It’s unlikely that the appearance of southern rust this late in the season will have any serious or detrimental effects on corn yields. Regardless, if you see tar spot or southern rust when scouting, please take pictures and submit reports to agpestmonitor or cornIPMPipe so we can keep the map for Illinois as up-to-date and accurate as possible. Decisions on foliar fungal disease management for the rest of the season may be headache-inducing, especially if you applied fungicides more than two weeks ago when there was little to no disease developing yet. Make decisions wisely using economic thresholds for disease incidence to avoid an unnecessary spray and help prevent fungicide resistance development.

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