Regional Crop Update: June 24 to July 2, 2019

July 2, 2019 9:45 PM
Blog Post

The past week finally brought some heat but it also brought some storms across the state leaving areas seeing wind damage and/or hail damage. In addition to some of the storm damage, thistle caterpillars, Japanese beetles, and weed management issues seemed to be some of the main concerns across the state that Iowa State University Extension and Outreach field agronomists have been hearing and seeing. Read on for more information about what’s happening in specific regions across the state.

Northwest Iowa

Joel DeJong (Region 1): “NW Iowa is really greening up, even along the Minnesota Border. You can see corn from V3 to V11 in the region – quite a spread. I know it will likely be August before some of those later fields will tassel this year. A lot of herbicides were applied this past week. Thistle caterpillar numbers dropped, and so far I have not found gall midge larvae, but expect to soon based on reports from surrounding areas. Heavy rain fell in parts of Lyon and Sioux County last week – with some locations getting over 4 inches of rain in the storm that passed. All of the expected damage from intense rains have been reported, along with some hail damage.”

Paul Kassel (Region 2): “The recent warm temperatures helped speed crop development in my area. Unfortunately, that warm weather brought some hail damage to parts of Clay and Palo Alto counties. The swath of damage in Clay county was about seven miles wide and 20 miles long. The hail damage hit an area where the corn and soybean crops were planted in early May and were some of the best looking crops in the area. Farmers and applicators are finishing corn post-emerge herbicide applications on the June planted corn and beginning applications on the soybean crop.”

Very limited corn recovery four days after the hail storm near Royal, IA in Clay County. Photo courtesy of Paul Kassel.

North Central Iowa

Angie Rieck-Hinz (Region 3): “During the week of June 24 to June 30, I had a dozen phone calls, emails, or texts about thistle caterpillars eating soybean leaves.  In nearly all cases the larvae were finishing their life cycles, so eating was ending and treatment was not warranted. I also did some field calls on herbicide injury, drift complaints, and answered several phone calls about if additional nitrogen was needed. Corn and soybeans range in size depending upon planting date. Corn ranges from V9 to V11 for early planted corn (mid to late April) to V3 for later planted corn (first week of June) Beans range in size from V2 to V5. I have not seen any blooming soybeans yet, but I would anticipate there are some out there. Farmers are trying to wrap up post-emerge application in soybeans before the rain that is predicted for everyday this this week happens. Rainfall during the week of June 24 to June 30 ranged from 0.33 inches at Webster City to 2.00 inches at Clarion. From April 1 to June 30, Clarion has had 17.54 inches of rain and Mason City has had 12.85 inches of rain.” 

Northeast Iowa

Terry Basol (Region 4): “The last couple of weeks in NE Iowa have provided good conditions for field operations to occur. Most producers have been able to complete sidedress nitrogen applications on their corn acres, as well as their planned post-emerge herbicide applications. Corn varies in growth stage from V4 to V5 through V8 and row closure. The first post-emerge herbicide applications on soybeans have begun and they range in growth stage from about V2 (late planted) to beginning bloom (R1). The week of June 17 provided the driest conditions where only 0.16 inches of precipitation was received at the NE Iowa Research and Demonstration near Nashua, according to the Iowa Mesonet. Last week (from June 23 to June 29), the farm received 1.7 inches of rain, with the heaviest rainfall occurring on June 27 (0.42 inches) and June 28 (0.9 inches). According to the Iowa Mesonet (see chart below), we are about 100 Growing Degree Days (GDDs) behind the average for this time of year in the growing season. As you can see though, the warmer temperatures have certainly helped in the past 7 to 10 days."

Growing degree day accumulation in 2019 compared to climatology for Nashua, IA. Source: Iowa Mesonet

Central Iowa

Meaghan Anderson (Region 7): “Corn is really starting to look nice across central Iowa and some soybeans are closing the rows, but we could really use a good rainfall across the area. Farmers are just finishing up soybean herbicide applications and late applications may be of concern for the corn next year, particularly with late fomesafen applications. Painted lady butterflies are all over the place as the thistle caterpillars pupated into their adult form after munching on soybean leaves in the last several weeks.  Most phone calls have been about herbicide applications, as well as continued calls about thistle caterpillar feeding and the arrival of Japanese beetles. It’s important to remember defoliation thresholds (30% on vegetative soybeans and 20% on reproductive soybeans) and that these insects have a habit of congregating, particularly along field edges.”

East Central, Southeast, and South Central:

Rebecca Vittetoe (Region 8): “Some storms rolled through this part of the state causing wind and hail damage in areas. Rainfall totals ranged from a less than 0.5 to 2 inches across my area. Corn ranges from V11 to V13 for April planted corn down to V3 to V5 for June planted corn. Soybeans range R2 down to about V1. Post herbicide applications have been the primary focus this past week. Questions this past week have centered around herbicide drift, herbicide applications, nutrient deficiencies, and insect feeding (thistle caterpillars and Japanese beetles).”   

Virgil Schmitt (Region 9): “Rainfall last week was from less than 0.25 inch to between 1.0 and 1.5 inches. Days for field work ranged from zero to four. April planted corn is mostly V11 to V12, mid-May planted corn is mostly V9 to V10, and June planted corn is mostly V5. Post herbicide applications are wrapping-up in corn. Soybeans are from R2 down to VC. Inquiries about herbicide use, herbicide injury, and cover crops dominated calls last week.”

Rainfall totals across the state for the past seven days as of July 1. Source:

Josh Michel (Region 11): “Much of southern Iowa received anywhere from 0.5 to 2 inches of rain last week. Some field operations including some much-needed post herbicide applications were able to get completed within the past week. April planted corn is V9 to V10 while June planted corn is around V3. Earlier planted soybeans are at R1, while June planted soybeans are at V1 to V2. Bean leaf beetles, Japanese beetles and thistle caterpillars have continued to caused some concerns with defoliation in soybeans. Common questions this past week have been on nitrogen management, late season weed management, summer forages, and prevented planting options.”

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



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...