Regional Crop Update: June 24 - July 2, 2024

July 2, 2024 2:58 PM
Blog Post

Flooding or flood damage in parts of Iowa, corn starting to tassel, corn rootworm, potato leafhoppers, waterhemp suriving post herbicide applications, and herbicide injury due to carryover or drift were "highlights" Iowa State University Extension and Outreach field agronomists saw over the last week. Read on for more specifics about what’s happening in fields across the state.  

Northwest Iowa

Leah Ten Napel (Region 1): “This past week NW Iowa has really come together to help clean up damage from flood waters in homes and communities. The flood waters have also impacted crop ground of course. The extent of damage on crop ground will depend heavily on the amount of time that crop was underwater. Farmers first step should be contacting their crop insurance agent to discuss impacted acres. The farmer will be given options to move forward from there based on their policy. If you are looking for more resources on flood impacted acres visit this webpage, or get ahold of me to talk through your options! Acres not affected by flood waters are coming along nicely. Because of the long planting period we can find both corn and soybeans in many different stages. Corn is turning a dark green and growing tall as its roots go deeper into the soil. Soybeans have canopied in many areas. A lot of post applications of herbicide were applied last week to soybeans causing some leaf tissue burning. Weed control has been a struggle as some fields had delayed chemical application. As the calendar and crop stages move along the chemical options get fewer and fewer. Insect and disease pressure has been low, but excess moisture this growing season may bring around more diseases than the past few years. Get out and scout, especially as we get closer to the corn and soybean reproductive stages! Keep in mind not all diseases are controlled by fungicide application, but it is good to know if diseases are present for future management.”

North Central Iowa

Angie Rieck-Hinz (Region 3): “We received additional rain late last week ranging from 0.8 inches at Webster City to 2.35 inches at Hampton. The wetter areas across my northern counties continue to receive rain and the southern counties I cover could use a small drink (which did occur overnight Monday July 1). Soybeans range from V4 to R2 and corn is V5 to VT. There is some downed corn from the winds of last week. I have seen a few Japanese beetles and a more than usual number of southern corn rootworm beetles (spotted cucumber beetle). Southern corn rootworm beetles overwinter south of Iowa, but the mild weather of this past winter may have led to some survivors. They are rarely a pest of concern. I have not seen any other insect or disease concerns but have received plenty of phone calls with concerns about tar spot. I did see my first spray plane on Sunday, June 30th, but I don’t know what it was spraying. There is still some side-dressing and post-applied herbicides going on, and I did see several folks row cultivating both corn and beans last week. I have had multiple calls about the efficacy of post-applied herbicides and I continue to see fields that are experiencing herbicide carryover into soybeans along with off-target movement of herbicides.”

Northeast Iowa

Terry Basol (Region 4): “Crops in the area are looking pretty good despite the amount of moisture that we've had in the last couple of weeks. Corn ranges from V4 to V10, depending on planting date. There are still some fields in the area exhibiting some nitrogen deficiency, but growers are steadily gaining with side-dressing and supplemental nitrogen applications. For most of the corn acres in the area, they have started looking a lot better. They are not as uneven and are starting to show a darker green color, as the nodal root system is taking over and pulling the needed nitrogen into the plant as the roots get deeper into the soil profile. Besides side-dressing, growers in the area are also finishing up post emerge herbicide applications. Soybeans range anywhere from V3 to R1 (plants have at least one open flower at any node), and the first application of post emerge herbicides has begun. Oats look really good in the area and have started to turn. Second cutting hay is either right around the corner or has just begun. According to the Iowa Mesonet, the NE Iowa Research and Demonstration Farm at Nashua received 4.19 inches of rain June 16 – 22, and 1.55 inches of rain June 23 - 29, for a total of 5.74” in the last two weeks, and 8.35" for the month of June.”

Josh Michel (Region 5): “Widespread rain showers came through Northeast Iowa late last week and over the weekend delivering up to 2 inches of rainfall. Thankfully, producers have been able to take advantage of a few dry days to complete N side dressing applications, post herbicide applications, and begin harvesting the second crop of alfalfa in some areas. With the consistent rainfall and warm temperatures, corn plants have been growing very rapidly. Now is a good time to start checking for corn rootworm injury feeding and looking for corn rootworm larvae by doing a float test in a 5-gallon bucket. There’s been increasing concern about disease pressure. However, even with the persistent rains, disease pressure remains low. Many early-planted soybean fields have reached R1. Because of this, producers should remember to check post-herbicide labels as to avoid damaging any flowers. Japanese beetles have also started showing up in many soybean fields. Oats are turning in most fields and continue to look really good. The majority of field calls last week consisted of nitrogen management, forage and small grain management, weed identification and control, along with a couple calls about possible pesticide drift and injury in soybeans.”

Japanese beetles soybeans
Japanese beetles causing some minor defoliation in a soybean field in NE Iowa. Photo by Josh Michel. 

Southwest Iowa

Aaron Saeugling (Region 10): “Knee high by the fourth a July has several meaning this year. The good corn will be well on the way to tassel, while the late plant and replant corn may only be knee in a few spots. Unfortunately, a few areas may have water knee high. Flooding is occurring along the Missouri river and other river bottom fields. This is a year for the good the bad and the ugly, just matters how many acres of each a farmer has. Most of the corn does look good now that we have had some heat and most corn has been sprayed with herbicides and we are not transitioning to disease development scouting. Soybeans are the in the vegetative to early flower stage in most fields. We have several different planting dates for soybean across SW Iowa. The earlier planted beans are beginning to flower and stretch out a little bit. Weed control is the biggest concern, and I have had reports of less than expected weed control. Most of this is caused by above normal precipitation reducing the soil residual and larger weeds at the time of application. I have also, witnessed some “hot” tank mix and adjuvant packages causing soybean injury on hot and humid days. So be careful when tank mixing products with aggressive adjuvants. Forages and pastures look good this year with the moisture and cooler temps to start July. Most alfalfa is starting to bloom, so I expect second crop of alfalfa to be cut soon.”

waterhemp sprayed growth regulator
Waterhemp looking twisted in a soybean field following a post herbicide application. Photo by Aaron Saeugling. 

East Central, Southeast, and South-Central Iowa

Rebecca Vittetoe (Region 8): “While parts of EC Iowa are considered abnormally dry, we did get a pretty consistent rain across this part of the state with totals ranging from just over 1 inch to over 2.5 inches (not counting what fell Monday, July 1 into Tuesday, July 2). The earlier planted corn fields started to tassel late last week, and soybeans are at R1. Now is a great time to check corn fields for corn rootworm pressure, especially if you are curious if you have either of the corn rootworm variants or to monitor how well your control methods are working. Yesterday (July 1), I saw a few adult corn rootworm beetles in a corn field as well as a pupa and several larave. Other insect pests I noted in fields over the last week included Japanese beetles and potato leafhoppers in alfalfa. Despite getting questions on disease pressure, especially concerns about tar spot, I haven’t seen much if anything in regards to disease in corn or soybean fields. Over the last week I’ve also had more inquiries about waterhemp surviving post herbicide applications. Take time to scout your fields and evaluate your herbicide effectiveness.”

Now is a great time to scout corn fields for rootworm pressure. Pictured above was larave, a pupa, and adult corn rootworm all found in the same EC Iowa field. 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 eastern Lee County and the largest amounts in the preponderance of the area. The U.S. Drought Monitor released on Thursday, June 27, 2024, indicated that, as of Tuesday, June 25, 2024, the approximate southeast half of the counties I cover was rated as abnormally dry. Most corn is about V11-V13 and looks good. I saw my first tassels emerging on Wednesday, June 26, 2024, and have seen a few poking out in a few fields since then. Most soybeans are at V6-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. Contacts last week mostly involved postemergence herbicides injury to soybeans, herbicide drift, tank contamination, in-season N applications to corn, and hail damage to corn, soybean, oats, and hay.”

rainfall totals map


drought monitor map
Source: U.S. Drought Monitor. 

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

field agronomist 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...