Regional Crop Update: July 20 - 28, 2026

The “cooler” temperatures were welcomed last week. Rainfall was spotty across the state, and unfortunately, the western part of the state, which has been drier, missed out on most of the rain. Corn pollination has wrapped up or is wrapping up, and soybeans are starting to fill pods. Overall, disease and insect pressure remain low across the state. Read on for more specifics on what ISU Extension field agronomists are hearing and seeing in fields around the state.

Leah Ten Napel (Region 1)

Cherokee, Ida, Lyon, Monona, O'Brien, Osceola, Plymouth, Sioux, Woodbury counties 

“Crops in the northwest corner of the state continue to show strong yield potential as corn moves from pollination into early grain fill and soybeans advance through flowering into pod development. Precipitation throughout the month of July has been light and highly variable, so some fields are beginning to show signs of stress on lighter soils. Scouting fields at this point in the growing season is still very important. Farmers should evaluate ears for successful pollination and monitor insect and disease pests. Levels of both have been low but could cause issues or yield loss in the future if left undetected or untreated. With much of the crop entering grain fill, weather during the next several weeks, particularly heat and moisture, will play a major role in determining final yields.” 

Josh Michel (Region 5)

Allamakee, Buchanan, Clayton, Delaware, Dubuque, Fayette, Jones, Linn, Winneshiek counties 

“Severe thunderstorms came through the region early last week, delivering heavy rainfall and strong winds to some areas. While most of the region received anywhere from 0.50 to 1.5 inches of rainfall, some isolated areas in Jones and Linn counties received up to 2 inches of precipitation. In general, most of the corn is around VT to R2, while soybeans are around R2 to R4. Disease management continues to be a concern while disease pressure remains low. The third crop of alfalfa is well underway across most of the region. The majority of recent field calls have centered around herbicide drift and injury, as well as scouting for crop diseases.” 

Meaghan Anderson (Region 7)

Boone, Dallas, Jasper, Madison, Marshall, Polk, Story, Tama, Warren counties 

“Much of central Iowa received more than 0.5" rainfall in the last week, with a few areas hit with much heavier totals, high winds, and hail. Corn is in the R1-R3 range in central Iowa and soybeans are mostly in the R3 (beginning pod) growth stage. I've received a handful of reports of pollination issues in corn. Insect and disease pressure reports are still low in both crops overall. With the find of southern rust in several Iowa counties in the last week, that has dominated my phone calls. I've been encouraging farmers to monitor their own fields and know which hybrids are more susceptible before making any decisions based on low pressure found in other counties.”

Rebecca Vittetoe (Region 8)

Iowa, Jefferson, Keokuk, Poweshiek, Washington, Johnson counties 

“The cooler temperatures last week were much welcomed, along with some rainfall that came on Monday last week. Totals ranged from a trace to over 1.5 inches. Areas in Johnson County received the heavier rainfall amounts. There were some stronger winds that came with the rain. Corn is mostly R2 to R3, and soybeans are mostly R3. Overall, insect and disease pressure remain low in both crops. However, with southern rust being found in eastern Iowa last week, I did get a lot of questions about that. So far, where southern rust has been found, pressure has been low. Gray leaf spot and bacterial leaf streak are still the most common diseases I have seen. Continue to scout fields. Questions this past week were mainly on what’s being seen for diseases and foliar fungicide decisions.”

 Virgil Schmitt (Region 9)

Cedar, Clinton, Des Moines, Henry, Jackson, Lee, Louisa, Muscatine, Scott counties

“During the last week, the counties I cover have generally received from 0.1 inch of rain to over 3 inches of rain, with the heaviest amounts generally around a line from Davenport running northwest toward Independence. Most corn fields are R3 to R4 and generally look good except stress is showing up on coarser textured soils. Little disease is present. Most soybeans are R3 and also look good, except stress is showing up on coarser textured soils. Again, little disease is present. Small grains and forages are also doing well. Calls last week mostly corn and soybean diseases and fungicide application decisions, especially with southern rust of corn being identified locally.”

Aaron Saeugling (Region 10)

 Adair, Adams, Cass, Clarke, Decatur, East Pottawattamie, Fremont, Mills, Montgomery, Page, Ringgold, Taylor, Union, West Pottawattamie counties  

“Isolated thunderstorms were welcomed in portions of western and southwestern Iowa this last week; however, most locations missed out on the rain. Western Iowa continues to be dry, and drought conditions are showing after the past week, with heat indexes over 100 degrees. Check areas that had heavy fog and a strong morning dew over the past week for disease development. Most planned fungicide applications have been applied to corn. I would be looking for gray leaf spot in the coming weeks. The majority of the other corn diseases will struggle with the excessive heat despite dew and foggy conditions. The corn crop has been hurt by the recent excessive heat in drought areas, and crop progress is moving along rapidly. A warm August will continue to speed this corn crop along. August is a critical time for maximizing soybean yields. Factors that all contribute to maximizing yield include soil moisture and weed control, as well as insect and disease pressure. While Mother Nature is responsible for August weather, continue to scout and make key management decisions when necessary. Currently, disease incidence is low along with limited insect pressure.”

Logan McCrea (Region 11)

Appanoose, Davis, Lucas, Mahaska, Marion, Monroe, Van Buren, Wapello, Wayne counties 

“Crops are continuing to progress across south-central Iowa, though some widespread precipitation would be very welcome. Areas received some precipitation with the weather system early last week, but overall, the majority of my area has received 2-4 inches of precipitation below average for the past 30 days. Corn ranges from R2 to R3, with disease pressure still fairly low. Soybeans are R2 to R3 and have tolerated the heat so far with low disease pressure as well. Hay cutting was going on over the weekend. Calls over the past week have mainly surrounded fungicide decisions and disease ID.”