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Soybean research and Extension specialists from land-grant universities across the country welcome you to join the next monthly informal discussion on crop production topics that are timely and relevant. When you join the Notes from the Field webinar series, you will get highlights and current issues from across the major soybean growing regions of the U.S. You will have the opportunity to ask questions specific to you and your operation.

While some much-needed rain did come this past week it seems that the drier areas continue to miss out or get minimal rainfall and the wetter parts of the state keep getting wetter. The rain also brought some hail, which caused some pretty significant damage not just to crops but property as well.

Despite the cooler conditions and precipitation (in some parts of Iowa) last week, the U.S. Drought Monitor categorizes most of Iowa in moderate to severe drought. As we approach tasseling, more and more questions around fungicides are being asked. 

I’ve had a lot of questions about soybean gall midge over the winter and in the last few weeks. Most fields have plants with 4-7 trifoliates and I’ve even seen some flowers! If you are connected with the Soybean Gall Midge Alert Network, you know midges have been active in Nebraska for a few weeks. But they first appeared in mid-June in Iowa, similar to 2019 and 2020.

The mass of water in corn follows a seasonal cycle. During the vegetative stages, corn is around 80% water. Corn water mass quickly accumulates during the vegetative stages. Maximum water mass occurs around 1830 Fahrenheit GDD after planting for many Iowa corn cultivars, aligning with the end of its R2 (blister) stage. At this stage around 70% of the plant’s mass is water. From then on, water content decreases until harvest, when it makes up only around 15% of the plant’s mass.

The hot and dry conditions last week resulted in many fields showing signs of stress. Thankfully, a much-needed rain fell across a good part of the state late last week and on Sunday evening. Unfortunately, most of NW Iowa seemed to miss out on the rain. With the much-needed rain, there was also some wind, hail, and tornado damage reported.

While some areas received some much need precipitation later last week and over the weekend, there was some hail that came with it. Some fields have pretty minor hail damage and other fields had some pretty significant hail damage.

For those folks dealing with hail damage, the first step should be to communicate with your crop insurance agent. Additionally, below are some resources that may be useful in evaluating the impact of the damage.

Today, our lab crew went to the Johnson Farm south of Ames, Iowa to evaluate a bean leaf beetle study. To our surprise, we found many V4-V6 plants with established soybean aphid colonies (Photo 1). It is not uncommon to find sporadic soybean aphids in June, but it is surprising to find a colony this early. Typically, we find established aphid populations on soybeans after bloom. Many of the plants had winged aphids among the colony.

While some areas did receive some much-needed rainfall across the state, most areas received very little to no rainfall this past week. Consequently, it wasn’t hard to see lot of corn fields with leaves rolling this past week across the state. Lots of POST herbicide applications, sidedressing, and finishing putting up the first cutting of hay went on this week.

Over the last 5 days, I’ve been asked numerous times about a small butterfly roaming the gravel roads and wooded areas around Iowa. It’s a fast, skittish insect and tracking down a good photo has been really tough. They are described by entomologists as mercurial, or subject to sudden and unpredictable behaviors. The best I could do was capture this small mass of adults over the weekend:

The following is a view of the moisture status for six locations in northwest Iowa where the soil was analyzed for spring subsoil moisture.  This discussion may or may not reflect the current soil moisture conditions in your area.  This article does attempt to account for stored soil moisture, 80% of spring rainfall and expected average rainfall for the rest of the growing season.

Across most of Iowa, corn is near V6 stage and much of Iowa is under some degree of drought stress. The exception being extreme southeast Iowa. Being at V6 stage means corn ear initiation is occurring and in the coming week the number of kernel rows on the ear will be determined. This is the second most critical time of yield determination with the first most important timeframe being the 2 weeks before and after pollination.

Micronutrients for soybean production, soybean cyst nematode management and white mold of soybean will highlight the summer field day at the Iowa State University Northern Research and Demonstration Farm near Kanawha.

For the second year in a row, we’ve been hearing multiple reports of fields with high grub activity in central Iowa, particularly between Ames and Ankeny. Typically, people were called out to the field for other reasons but found grubs once they started digging. In fact, a field I visited last week looked pretty healthy considering some other challenges farmers are facing, such as dry soil conditions, frost damage, and uneven emergence.

Most people are already finished with their first cutting of alfalfa throughout Iowa, but each of our 10 field agronomists reports that alfalfa weevil activity continues and has been much worse than they’ve seen in over a decade. Lance Scott in southwest Iowa took this short video to show significant injury. Alfalfa weevil only has one generation per year. The larvae are the most damaging stage, defoliating leaves and sometimes only leaving the veins behind.

Most herbicide labels caution against applications made under environmental stress such as prevailing hot and dry conditions in Iowa this year. This is because of increased risk of crop injury and/or decreased weed control. Weeds growing under hot, dry conditions are often difficult to control because of the development of a thicker waxy cuticle, which serves as a barrier for herbicide absorption.

This past week brought a range of field activities from replanting and POST herbicide applications to putting up hay and sidedressing nitrogen. Herbicide injury and carryover, dry conditions, yellow corn, and alfalfa weevils have been some of the more common issues ISU Extension field agronomists have observed in fields this week. Read on for more specifics for what’s happening in different regions across the state.

Northwest Iowa

With technology advancing all the time, it’s hard to resist the appeal of new equipment. However, there are many upgrades available that can be added to your existing planter to achieve speed and efficiency next planting season. When we talk about upgrades to your planter system, there are three main areas to look at.

Seed Meter

As we continue the postemerge herbicide applications for corn and begin this process for soybeans, it’s important to be on the lookout for temperature inversions, Photo 1.  This blog will discuss what temperature inversions are, why they can be dangerous for pesticide applications, and how to identify when temperature inversions are happening.

The dry conditions are causing some to see what is known as “floppy” corn (aka rootless corn). Rootless corn is easy to diagnose – simply dig up plants that are not standing erect like they should be, then gently knock off the soil to get a look at the roots. With rootless corn you will see the seminal roots but no, or poorly developed, nodal roots.