Regional Crop Update: July 1 - July 9, 2024

July 9, 2024 11:58 AM
Blog Post

Hail and wind damage to crops, corn rootworm, nutrient deficiencies, herbicide injury/drift, and  waterhemp surviving post herbicide applications were common issues or questions reported by Iowa State University Extension and Outreach field agronomists over the last week. Read on for more specifics about what’s happening in fields across the state.  

Northwest Iowa

Gentry Sorenson (Region 2) “We received anywhere from 1 inch to 2.5 inches of rain across the region.  Spencer has received over 25 inches of rainfall since April 10.  The recent rainfall from July 1 to July 9 left fields very wet. There was not a lot of field work completed in recent days but those that missed the rain or received lighter amounts were able to spray post emergence herbicide on corn and soybeans. Before the rain last week many were working on herbicide applications to corn and soybeans along with side dressing N to corn. Early planted corn is just starting to tassel, other fields are very close to tasseling.  Some replant corn and late planted corn have a few days before we see tasseling.  Soybeans are at R1. IDC is present in some soybean fields. With the rainfall it has been difficult to complete post emergence spraying in some soybean fields.  Field calls and phone calls have been related to concerns on rainfall and drift complaints.”

North Central Iowa

Angie Rieck-Hinz (Region 3): “A hail storm went through multiple counties on the evening of July 6. Damages range from barely tattered corn and soybean leaves, to complete defoliation of beans and corn broken off at 15-20 inches in height. To add insult to injury, some of that same area received upwards of 6 inches of rain the next day, July 7, leaving many acres with standing (flowing) water. Two resources, Hail on Soybean in Iowa and Hail on Corn in Iowa address potential yield losses and management for the remainder of the growing season. Corn ranges from late vegetative stages to R1 and beans are mostly R2.  So far, there is very little disease or insect pressure. I have seen Japanese beetles feeding on soybeans, but at very low pressure. I saw my first western corn rootworm beetle on July 9."

hail soybeans
Injured soybeans from the hail storm on July 6, 2024.  South of Hardy, Iowa. Photos: Angie Rieck-Hinz, ISU.

hailed corn

Injured corn from hail storm on July 6, 2024. Located along D20, 2 miles north of the Stonega Elevator. Injury includes defoliation and huge splits and bruises on stalks.  Photos: Angie Rieck-Hinz, ISU.

Northeast Iowa

Terry Basol (Region 4): “Field operations were challenged last week due to precipitation events throughout the week. The early planted corn fields have begun tasseling, whereas the rest of the corn in the area ranges from V5 to V12, depending on planting date. Soybeans range anywhere from V4 to R2 (plants have at least one open flower at one of the two uppermost nodes on the main stem with a fully developed trifoliolate leaf node). First pos-emerge herbicide applications for soybeans continue but have been frustrating for growers to complete due to the rainy weather. Oats continue to look really good, and according to the USDA-NASS Crop Progress Report for July 8, 68 and 49% of the oat crop is turning in NC and NE Iowa respectively. Second cutting hay is underway in the area with about 30% completed. Recent wet weather has made it challenging for growers needing a 3-4 day window of dry conditions to get it put up for long-term storage. According to the Iowa Mesonet, the NE Iowa Research and Demonstration Farm here at Nashua received 3.23 inches of rain the week of July, with 2.28 inches being received on Tuesday, July.

Josh Michel (Region 5): “Persistent rain showers came through NE Iowa last week and over the holiday weekend delivering up to 3.5 inches in isolated areas. Over the past 30 days, most of NE Iowa has now received anywhere from 2 to 4 inches above our normal expected precipitation amounts. In-between showers, producers have been trying to finish up any remaining nitrogen side-dressing treatments, post herbicide applications, and continue harvesting the second crop of alfalfa. Due to the surplus of moisture and warm temperatures, crops continue to grow very rapidly. While the first tassels of the season can be spotted in some early-planted corn fields, I’d expect most fields to begin to tassel within the next couple weeks. Strong winds from some severe storms have caused lodging in isolated areas. I expect most of this corn to recover well enough to not cause any harvest issues. While some wet spots continue to be seen in fields, generally most of the corn looks good throughout the region. Most of the soybean fields have now reached R1-R2. Because of this, producers should remember to check post-herbicide labels to avoid damaging any flowers. Weed escapes continue to be a major concern as some post herbicide applications may have been too late to control rapidly growing waterhemp.  Japanese beetles have also started showing up in most fields. Thankfully damage has been minimal so far. Oats have turned in most fields, and I’d expect harvest to begin within the next couple weeks. There has been some wind damage in isolated areas, but overall, most fields continue to look really good. Forages continue to benefit from the surplus of rain, but many producers are anxiously waiting for a weather window to finish up the second crop of alfalfa to help alleviate increasing potato leafhopper feeding. Other field calls last week centered around mid-season N management for corn, forage and small grain management, weed escapes and control, and several calls regarding possible herbicide drift and injury.”

potato leafhopper damage
"Hopper burn" in an aflalfa field in NE Iowa due to potato leaf hopper feeding. Photo by Josh Michel. 

Central Iowa

Meaghan Anderson (Region 7): “Central Iowa received anywhere from 1 inch to more than 6 inches of rainfall in the last week. Madison and Warren counties received the most significant rainfall in the last week, with parts of Marshall, Tama, Polk, Jasper, and Dallas counties not too far behind. Much of central Iowa has been inundated with over 20 inches of rainfall in the last 90 days. Corn is mostly in the very late vegetative stages, up to R1 in some fields. Many tasseling fields are unevenly developing tassels, a remnant reminder of our tough start to the growing season. Soybean are mostly in the early reproductive stages, with many fields at R1 (beginning flower) or R2 (full flower). While herbicide applications have mostly stopped in both crops, many are still asking what’s going on with the weeds. Survivors are noticeable in fields, especially along field edges and wherever heavy pressure exists. Disease pressure is overall very low (for now), but corn rootworm activity has been noticeable in central Iowa corn fields. Most phone calls recently have been about fungicide decisions, weed pressure, and nutrient deficiencies (sulfur in corn, IDC in soybean).”

Southwest Iowa

Aaron Saeugling (Region 10): “Wild weather continues to plague SW Iowa. Last week we had isolated hail in western Pottawattamie County and strong winds and heavy rainfall. With those storms came hail damage and corn breakage. Most corn in the area is tasseling or will be in the next week. Outside of weather damaged areas corn looks good. I expect foliar fungicide applications to begin this week. Soybeans are really growing now with added heat this past week and the current forecast. Still have a few weed control challenges with large waterhemp. Insect pressure is low, but we can find soybean gall midge and Japanese beetle in fields. Most soybeans are flowering and canopies have closed on narrow row soybean fields.” 

East Central, Southeast, and South-Central Iowa

Rebecca Vittetoe (Region 8): “Across EC Iowa over the last week most area received 1.5 – 2.5 inches of rain, with isolated areas receiving higher amounts. Wind did come with some of that rain. Corn ranges from the late vegetative stages up to VT/R1, and the majority of the soybeans are R1 to R2. “Why isn’t my waterhemp dying?” has been a common question I’ve received over the last week. In some cases, it may still be on its way out (just not brown and crispy), but there are some that look like they have survived the post herbicide application and were only 2-4 inches big. On the insect side of things, now is a great time to evaluate corn roots for rootworm feeding. Japanese beetles are also present. Disease pressure has been low in both corn and soybeans. In corn, I’ve seen or had reports of common rust, bacterial leaf streak in corn, and tar spot. In soybeans I’ve just seen bacterial disease issues, but again nothing major. While scouting fields do keep an eye out for two newer pests – soybean gall midge and a newer weed Asian copperleaf which at a quick glance can look similar to waterhemp. Questions or inquires over the last week have been on fungicide decisions, weeds not dying, corn rootworm, potassium deficiency, herbicide drift/injury, and wildlife damage in crops.”

K deficiency
Corn field with potassium deficiency showing up as noted by the yellowing along the leaf margins. Photo by Rebecca Vittetoe. 

Virgil Schmitt (Region 9): “Rainfall during the last week in the counties I cover was from less than 0.5 to about 3 inches, with the smallest amounts in southeastern Lee County, 1-2.5 inches amounts in the preponderance of the area, and the heaviest amounts in northeastern Jackson County. Central Lee County received strong winds and hail over the weekend. Most corn is about V14-R1 and looks good. Most soybeans are at R2 and also look good. Oats are turning and continue to look good. All crops appear to have few disease or insect issues except potato leafhoppers are above threshold in many alfalfa fields. Winged grasshoppers can now be observed, and katydids have begun to “sing.” Contacts last week mostly involved herbicide drift, in-season N applications to corn, fungicides for both corn and soybean, Japanese beetles on both corn and soybean, and potassium deficiency in corn. I also worked with an individual who had a total bee kill as a result of the neighbor not looking at FieldWatch and spraying the adjacent soybean field with a fungicide / insecticide mix. The cost of bee replacement and lost honey production is estimated to be in excess of $5,000.00.”


Check out the map below to find your local ISU Extension field agronomist and find their contact information here!

field agronomist region map



Rebecca Vittetoe Field Agronomist in EC Iowa

Rebecca Vittetoe is an extension field agronomist in east central Iowa. Educational programs are available for farmers, agribusiness, pesticide applicators, and certified crop advisors.

Areas of expertise include agronomy, field crop production and management of corn, soybeans, and...