Regional Crop Update: June 15 - June 23, 2026

Another week with a similar pattern in rainfall with northwest and west-central Iowa getting lower amounts and heavier amounts in east-central and southeast Iowa. Both of these extremes are having an impact on crops. With corn getting into the mid-vegetative stages now and soybeans starting to reach the reproductive stages, ISU Extension and Outreach field agronomists share what they are hearing and seeing in their respective areas of the state.  

Josh Michel (Region 5)

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

“Wet weather and high winds last week continued to hinder post herbicide applications. Several rounds of rain showers came through the region and delivered anywhere from 0.50 inches along the Minnesota border, to around 1 inch in areas along Highway 20 from Independence to Dubuque. Severe weather and isolated heavy rainfall came through the Cedar Rapids area, with some locations reporting up to 3 inches of rainfall. Weed management continues to be a major concern as many weeds are rapidly growing and post applications have not been timely due to less-than-ideal weather and field conditions. In general, most of the corn is around V5–V7, while soybeans are at V3–V5. Small grains and forages continue to look good with all the recent rainfall. There have been some reports of lodged oats and leaning corn from the recent severe weather. Most of the corn should upright itself within several days. The majority of field calls over the past week continue to be centered around weed management, as well as herbicide drift and injury.”

Meaghan Anderson (Region 7)

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

“Central Iowa received pretty variable rainfall over the last 7-10 days, but everyone got something. Northern Story, Marshall, and Tama County were the big “winners” with totals topping 3 inches in some areas. Corn is in the mid V-stages and I’m beginning to get regular reports of disease finds – bacterial leaf streak, tar spot – all at low levels. Nitrogen questions have been prevalent in the last week as rainfall totals continue to add up and some corn looks yellow. I received one report of European corn borer in non-Bt corn this week, so farmers growing non-GMO/RR-only corn should monitor their fields. Soybeans are in the V5–R2 growth stage. Herbicide phytotoxicity is prevalent across the landscape as people finish up postemergence herbicide applications. Most phone calls recently have been about spray drift, weed control, nitrogen management questions, and pasture management.”

Rebecca Vittetoe (Region 8)

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

“Another wet week in this part of the state with rainfall totals ranging from 1.5 inches up to more than 5 inches in areas. The heavier amounts seemed to fall in parts Johnson, Keokuk, and Washington counties. There were a few days last week when fields were fit to get into and catch up on post spraying. Corn is mostly V8–V13 and soybeans are V5–R2. As a reminder, double check herbicide labels for growth stage restrictions. With the wet conditions, some corn and soybean fields—or areas in the fields—are looking yellow. We just haven’t had a chance to really dry out much. While tar spot has been reported in other parts of the Iowa, I haven’t found any in my area. However, I can find anthracnose leaf blight on lower leaves in corn fields, particularly in continuous corn fields. I’ve also seen some holcus spot in corn. On the insect side, Japanese beetles are present. The main questions this past week have been on the wet conditions, disease potential, weed management, and herbicide drift.” 

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 3+ inches of rain south of I-80, with heavier amounts locally. North of I-80, rain tapered off to about 0.5 inch near Highway 20. There is some low-land flooding and ponding.  Most corn fields are V10–V12 and look good. However, some fields are showing nitrogen deficiency symptoms. Soybeans are mostly V5–V7 and also look good. I have not seen any blossoms yet, but I know of some fields as far along as R2. Small grains and forages also are doing well. Japanese beetles are emerging. Calls last week mostly centered around weed management in soybeans.” 

 Logan McCrea (Region 11)

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

“Precipitation amounts over the past week range anywhere from 1 inch to 2.5 inches, keeping soils saturated for a while longer. Soils really could use 7-10 days to dry a bit and get some oxygen back in their system, as there are a fair number of yellowing areas within fields from excessive moisture. Corn stages range from V7–V12/V13, while soybean stages range from V4–V6 and flowers are becoming easier to find within fields lately. Following the hail on June 11, a fair number of soybeans were going in the ground before the rain this past weekend. One or two corn fields may have been replanted as well, but the vast majority of corn is being left as is. Weeds continue to grow and accumulate more and more size and are going to be considerably difficult to tackle when mother nature allows us to get back out into the fields. Insect wise, Japanese beetles are beginning to be found in fields as well, so they will be another item to keep an eye on. Pastures look good still as temperatures have stayed cool, and hay was getting put up last week in some of the areas that had avoided a bit of the precipitation. Calls over the last week mainly surrounded hail injury on corn and soybeans, but also some weed ID and management questions.”