Regional Update: August 9 to August 24, 2021

August 24, 2021 10:38 PM
Blog Post

The drier and warm conditions have really pushed crops along across the state. In addition to the drought concerns and issues related to the drought, other common observations made in fields across the state include more sightings of tar spot, sudden death syndrome and/or brown stem rot in soybeans, and corn rootworms. Read on for more specifics on what’s happening in fields across the state.  

Northwest Iowa

Joel DeJong (Region 1): “There are definitely “haves” and “have nots” around NW Iowa. Some areas aren’t coming close to getting the water needed to finish this crop, in fact some are finishing prematurely now. At the same time, fields ten miles away might have received 5+ inches of rain more than these stressed neighborhoods and look great. Silage harvest started early last week, of course on some of the poorer fields. Estimated yield reports for at least some of those fields was quite low. Silage harvest on better fields began in some areas this week, but others are still too wet to chop. Soybeans in the really dry areas were actually wilting during the daytime last week, while in other areas they looked great, too. However, there has been more white mold showing up recently in parts of those areas that received good rainfall during the first half of July. Sudden death syndrome (SDS) has been observed at times, and spider mites continue to cause some damage occasionally. I had the chance to visit the area that was hailed out in late June in Plymouth County, and found corn a week post-tassel, and soybeans fully flowered (R2). These acres will certainly need quite a bit more time. A reminder to all producers, as we reach maturity in these cornfields, you will really need to evaluate for standability and prioritize your harvest!”

Corn field that has missed most of the rains and is finishing prematurely. Photo courtesy of Rebecca Vittetoe.

Gentry Sorenson (Region 2): “Rainfall last week ranged from 0.25 inches in Storm Lake to over an inch in other areas.  The D3 drought (extreme drought intensity) has extended in the area that I serve to include parts of Palo Alto County as well as an area that extends further south in Kossuth County. Parts of Clay and Dickinson counties and all of Emmet County that were previously in this status remain in the D3 intensity. Pastures in the area lack height and regrowth from the lack of rainfall. Corn is at the R5 growth stage (dent) with soybeans fields at the R5 to R6 growth stage. In some soybean fields pod abortion can be found on plants that are experiencing heat and drought stress. Corn ears in drought stressed areas are displaying tip back of the corn ear. Incoming calls were concerning drought stress to crops and questions regarding corn and soybean yields.”

Pastures are looking pretty tough in this part of the state. Photo courtesy of Gentry Sorenson.

Northeast Iowa

Terry Basol (Region 4): “Most of the corn in the area is at dent (R5) and up to ¼-milk line progression. Soybeans are primarily somewhere in the R5 stage up to R6. In regards to crop condition, corn and soybeans are doing their best to holding their own amidst the drier weather conditions. For the lighter soil textures in the area, firing in the lower canopy and tip-back on the ears has been observed in corn fields, but for the medium to fine soil textures, most ears are filled out to the end. Soybeans continue to roll or flip their leaves. Recent rains over the past couple of weeks in the territory will still help both corn and soybeans in dry matter accumulation, which results in added test weight.  Hay fields look pretty good considering and should be able to produce another cutting for producers. Disease and insect activity remains relatively low in both corn and soybeans. Rainfall totals over the past weekend ranged from 0.5 inch up to 3 inches in some isolated areas. The map below from the Iowa Mesonet shows that parts of NE Iowa range anywhere from 4 to almost 11 inches deficit of precipitation from average for this year’s growing season (April 1st through August 24th).

Rainfall departure from average across the state of Iowa from April 1 to August 24, 2021. Source: ISU Mesonet.

Josh Michel (Region 5): “Most of NE Iowa has received some much needed rainfall. This came at a critical time as both corn and soybeans are rapidly maturing. Unfortunately, there are some areas in Buchanan and Fayette counties where crops are showing symptoms of severe drought stress. Many corn fields I’ve visited lately have been at R5 (or dent stage) with fields past the ¼ milk line. Some dairy producers have started harvesting corn silage, and I’d expect many others to begin shortly. Soybeans are generally around R6 as the uppermost pods are being filled. While a third crop of alfalfa is getting finished up, I have been seeing and hearing reports of moderate hopper burn persisting in some areas. Pastures continue to hang on in areas where they have received rainfall, otherwise warming temperatures have caused many to go dormant. Recent field calls have centered around corn rootworm management, corn silage, alfalfa and forage seeding management, and cover crop considerations.”

Hopper burn is being observed in some alfalfa fields. A reminder to get out and scout your alfalfa fields. Photo courtesy of Josh Michel.

Central Iowa

Meaghan Anderson (Region7): “Much of my area received rainfall in the last week, but parts of Madison, Warren, and Jasper counties missed out this time. Corn is solidly in the R5 (dent) stage, with many corn fields past the ¼ milk line and some possibly nearing R6 already. Corn has been looking very stressed in the afternoons with the hot weather. Brief yield checks over the last week have shown good kernel counts, but smaller kernels and relatively short ears; we’ll see how much this crop was able to fill in those kernels when the combines start running in just a few short weeks. I’ve seen a little more tar spot in some central Iowa fields, but it hasn’t advanced to the ear leaf in most fields or been very prevalent due to weather. Soybean are solidly in the R6 stage with some of the shorter relative maturity varieties looking like they’re turning in parts of fields. Most calls recently have been about soybean – stem disease, potassium deficiency, sudden death syndrome, and brown stem rot. Now is a great time to check fungicide vs. no fungicide treatments in fields and weed control in order to make notes and plan for future years.”


Good reminder if you see what looks like SDS in fields to split open the stem and double check you are not seeing brown stem rot instead. Photo courtesy of Meaghan Anderson.

East Central, Southeast, and South Central Iowa  

Rebecca Vittetoe (Region 8): “Rainfall has been spotty the past couple of weeks with totals ranging from trace amounts to some areas getting closer to 2 inches. Crops have really been pushed along with the warmer and drier conditions. Most corn fields are at R5 with many at ¼ milk line, and soybeans fields are late R5 to R6. It was not uncommon to see some soybean plants aborting pods the last couple of weeks. Over the last couple of weeks it’s been easier to find tar spot in some EC Iowa corn fields, and I’ve also received questions about sudden death syndrome and/or brown stem rot in soybean fields. Corn rootworms continue to generate a lot of questions. I've also seen and had a few isolated reports of corn aphids."

Virgil Schmitt (Region 9): “Rainfall during the last two weeks in the counties I cover was generally less than 0.25 inch along the I-80 corridor with amounts increasing both north and south of I-80 to over 2.0 inches. In general, temperatures during the last week in the counties I cover were 1 to 2 degrees above normal. Corn is generally in early R5 and soybeans are generally late R5. There are few insect or disease problems at this time. Moisture stress in corn is showing up on coarser textured soils along the I-80 corridor. Calls and farm visits last week mostly involved corn rootworms and weed management.”

Rainfall totals across the state from August 9 to August 23, 2021. Source:

Clarabell Probasco (Region 11): “The South Central region has had mostly dry weather the past couple of weeks. A rain system worked its way through the area on August 13th, with precipitation accumulating anywhere from a few tenths to a few inches. Corn fields are in the dent stage (R5), and soybean fields are being seen in full seed (R6) stage. We are starting to see some third cutting of hay occurring. In the past week, the presence of tar spot was confirmed in a few corn fields in Monroe County. Tar spot is a newer disease for the state of Iowa. It was first confirmed in eastern Iowa in 2016. More information on this disease can be found here.”

Tar spot found in a field in Monroe County. Photo courtesy of Clarabell Probasco.

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...