Regional Crop Update: June 10 - June 18, 2024

June 19, 2024 5:36 AM
Blog Post

Areas in Iowa remained on the drier side last week while other areas received some heavier rain and even some isolated large hail in areas. Herbicide injury, Asian copperleaf, tar spot, nitrogen management, and weeds surviving herbicide applications were some of the hot topics or issues Iowa State University Extension and Outreach field agronomists saw over the last week. Read on for more specifics.

Northwest Iowa

Leah Ten Napel (Region 1): “Northwest Iowa has been facing challenges with weather this past week with large amounts of rainfall and large hail in some areas. The area affected by hail seems to be small, but the damage was substantial. Damaging storms are forcing growers to evaluate the need for replant or extra management for the rest of the growing season. Additional hail resources can be found here. Most corn is at the V3-V8 stage. Soybean stages are ranging V1-V4. Fields are looking good as canopies start to close. Post applications of chemical are happening, although strong winds are making that difficult." 

Hail damage on corn from a system that moved through NW Iowa on June 12, 2024. Photo by Leah Ten Napel. 

Gentry Sorenson (Region 2) “Rainfall occurred over region 2 from the 16-18th.  Rainfall is forecasted across the area for the next several days.  Field work before the recent rainfall consisted of finishing soybean planting, replanting of corn and soybeans due to past wet field conditions, post emergence herbicide applications to corn and soybeans, and finishing up forage harvest.  Corn growth stages ranges from V1-V7, with corn averaging around V4-V6.  Soybean growth stage ranges from VE-V3, stand evaluation, replanting and “thickening up” of soybean stands was observed.  Phone calls and field calls were regarding herbicide drift, planting, and stand evaluations. 

Northeast Iowa

Terry Basol (Region 4): “We had a relatively dry week last week, which allowed farmers to continue field operations. Corn ranges from about V2 – V7, with some at V8 for the earliest planted fields. Soybeans range from just planted to V3. All of the corn and soybeans have now been planted for the area, including the replanting’s that have needed to be done due to ponding issues and saturated soils. Field operations have comprised of post emerge herbicide applications in corn and soybeans, along with nitrogen applications in corn, both planned and supplemental due to excessive moisture. First cutting hay is completed with good tonnage and hay quality. Oats continue to look good in the area, with over half of the acres now headed out. I have seen some herbicide carryover due to last year’s drought conditions and the long half-life of some active ingredients (despite this spring’s rainfall). Pictured below is a field with HPPD (Group 27) carryover to soybeans. Common symptoms of HPPD injury include bleaching or chlorosis of the leaves resulting in necrosis later, malformation or crinkling of leaves, and stunted growth. For more information on herbicide carryover to soybeans, check out this ICM article titled “Identifying Common Herbicide Symptoms in Soybean”.  Regarding precipitation received in the area, according to the Iowa Mesonet, the NE Iowa Research and Demonstration Farm here at Nashua received 2.48 inch of rain the week of June 3 and 0.08 inch of rain the week of June 10, for a total of 2.56 inches in the last two weeks."

HPPD injury on soybeans
Bleaching or chlorosis, stunted growth, and malformed leaves are syptoms of HPPD injury in soybeans. Photo by Terry Basol.  

Josh Michel (Region 5): “Farmers were able to take advantage of a few dry days last week to focus on finishing up the first crop of alfalfa, continue post herbicide and begin side dressing applications. Most of the region did receive some rainfall, but it was generally around 0.25 to .50 inch. Some isolated areas did receive up to 1 inch of rainfall. Early planted corn fields can be staged up to V8, while later planted corn fields are anywhere from V2 to V4. Side dressing applications and many post herbicide applications have been occurring across the region. Earlier planted soybeans are generally around V3 to V4, while later planted soybeans are at V1 to V2. Be sure to check herbicide labels as I would not be surprised if some soybeans began to flower by the end of the week. Oats are heading out and generally look very good at this time. The majority of field calls last week consisted of nitrogen management, forage management, weed identification and control, along with a few calls about possible pesticide drift and injury.”

Central Iowa

Meaghan Anderson (Region 7): “Most of central Iowa received very little rain last week, while a few in the western part of my territory received over 0.5” in rainfall over the weekend. We could use a good drink, as crops are growing quickly and the soil surface is quite dry and hard from earlier pounding rains in some fields. Corn varies in stage, but much of the early planted corn is bigger than V9. I’m receiving fewer calls about uneven corn as it has reached nitrogen and put down roots deeper in the soil. With the tar spot finds in central Iowa over the last 10 days or so, I’ve been getting more phone calls with questions about this. It is absolutely worth scouting fields to see whether you can find any in your fields, but it is NOT yet time to make a fungicide application based on these finds. Corn rootworm larvae should be feeding on roots by now, so it is a good practice to dig roots and float larvae in fields with suspected issues (2023 article linked). Soybeans are beginning to flower and farmers are finishing up POST herbicide sprays in many fields. Narrow rows are getting closer to closing and recovering well from any foliar burn from those POST applications. Some iron deficiency chlorosis (IDC) is showing up in high pH areas in central Iowa fields. Keep scouting fields for soybean gall midge, Asian copperleaf, and other issues like weeds surviving herbicide applications. Most phone calls in the last week were about herbicide drift, weeds surviving applications, how much nitrogen we have left, corn rootworm, and tar spot.”

- waterhemp with herbicide injury two days after an application of glufosinate and 2,4-D.
A corn field with heavy waterhemp pressure right along a field edge. Be scouting your fields not only for weed pressure but also follow up to see how effective herbicide applications where. Photo by Meaghan Anderson. 

Southwest Iowa

Aaron Saeugling (Region 10): “Early planted corn is past the “ugly duckling” stage and is off and running. Most of the early corn is V8 - V10. Top dressing of urea is in full swing and most herbicide application have been applied to the early corn. Some of the later planted corn is in the V4 - V6 stage and taking off with the recent heat. Corn that was mudded in has sidewall compaction and is struggling in areas that are heavy clay soils.  Several “weird patterns” have emerged in the past few weeks in corn. I often get questions on the cause for this and no one factor is responsible. Often it may be residue cover, nitrogen, and old tillage or combine spreader patterns. Forages are doing very well compared to previous years. Most reports are very good for alfalfa and grass hay yields and quality. For heavy fescue pastures, now would be a good time to evaluate those for mowing to control endophyte populations. Bull turnout time is here so be aware of animal health issues like foot rot, pinkeye, and summer pneumonia. Soybeans are the story this week. Several fields are struggling to gain height ahead of flowering. I have observed some fields starting to flower. Weed control is an issue and lack of uniformity in stands. Weed control has been good on fields that received a pre-emerge application; however, total post programs ae getting “weedy” and need sprayed when the wind allows.”

Soybean flowering
Soybean plant at the R1 stage, which is when there is an open flower anywhere on the plant. Photo by Aaron Saeugling. 

Earlier planted corn field in SW that is now past the ugly dukling stage and really taking off. Photo by Aaron Saeugling. 

East Central, Southeast, and South-Central Iowa

Rebecca Vittetoe (Region 8): “With minimal to no rainfall across the counties I serve over the last week, we could really use a good shot of rain. Over the weekend you could start to see corn plants in lighter soils or more compacted areas rolling their leaves in the afternoon. The earliest planted corn is V9-V11 and the earlier planted soybeans are V4-V5. I haven’t seen a soybean field at R1 yet, but would expect to see flowers showing up soon. Calls or inquires over the last week included sulfur deficiency, herbicide injury, nitrogen loss concerns, weed identification, corn rootworm egg hatch and larvae feeding, and potato leafhopper concerns. As you are out looking at fields over the next week make note of how well post herbicide applications worked, keep an eye out for Japanese beetles emerging, potato leafhoppers in alfalfa, and now is also a good time to start doing the corn rootworm larave float test."

Japanese beetle on corn leaf
Japanese beetles can now be found out and about. Photo by Rebecca Vittetoe. 

Virgil Schmitt (Region 9): “Rainfall during the last week in the counties I cover generally was one inch or less. Most corn is about V7-V9 and looks good. Post-emergence herbicide applications are wrapping up. White flag leaves from rapid-growth syndrome can be seen in a few fields. Most soybeans are at V2-V5 and look good.We are at the overlap time of hay harvest when a few first-cutting fields are being mowed on the same day as a few second-cutting fields are being mowed, all with a mile or two of each other. Oats has been headed out for a few weeks and continue to look good. Contacts last week mostly involved corn postemergence herbicides – selection, injury, and (lack of) performance, nitrogen injury to corn, tar spot, and weed identification.”

rainfall totals across Iowa for the week

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...