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Moth flights into Iowa were drastically reduced during Week 8 (May 19 to May 25), partly because of fewer moths but also likely due to the fact that recent storms took out several traps across the state. Our cooperators recorded only 51 black cutworm (BCW) moths and, for the first time since Week 1, no significant flights were recorded.

This is part one of a three-part series on nitrogen management this spring. Read part two, “Navigating Nitrogen Management in Wet Spring Conditions – Estimating Nitrogen Losses,” and part three, “Navigating Nitrogen Management in Wet Spring Conditions – Does the corn need more nitrogen?”.

This is part three of a three-part series on nitrogen management this spring. Read part one “Navigating Nitrogen Management in Wet Spring Conditions – Nitrogen Loss Mechanisms” and part two “Navigating Nitrogen Management in Wet Spring Conditions – Estimating Nitrogen Losses.”

Do I need to apply additional nitrogen?

This is part two of a three-part series on nitrogen management this spring. Read part one, “Navigating Nitrogen Management in Wet Spring Conditions – Nitrogen Loss Mechanisms,” and part three, “Navigating Nitrogen Management in Wet Spring Conditions – Does the corn need more nitrogen?”.

While the title is written with some jest, the sentiment is one I’ve been thinking about a lot this spring. With few highly effective postemergence herbicide options for waterhemp control, farmers must prioritize residual herbicides as a first line of defense. While there are numerous residual herbicides available, most soybean residual programs are based on the PPO inhibitors (HG 14).

Black cutworm (BCW) moth flights seemed to wind down a bit during Week 7 (May 12 to May 18). Our cooperators recorded 106 BCW moths around the state. Only one significant flight (Buena Vista County, May 14) occurred during Week 7, which is a big change from previous weeks where several significant flights have been reported.

The weather provided a window for farmers to get back in fields and continue to make planting progress. Other field activities in the last week included tillage, herbicide applications, harvesting first cutting of alfalfa, and rotary hoe operations in areas dealing with soil crusting.

Last week at our Field Crop Scout School one resource that we shared was a list of crop scouting related apps and web-based resources. There are a lot of apps and web-based resources out there that can be helpful when it comes to crop scouting.

Check out the list we complied below or click here to download a pdf version. If you have other apps or web-based resources you like to use, please let us know!

The U.S. Environmental Protection Agency (EPA) is asking for public comment on Dicamba, Glufosinate-P, and Acephate.

Bayer CropScience has requested the EPA to register a new use of dicamba on dicamba-tolerant soybeans and cotton.

You may have heard of a special entomological event happening this year. It’s true, a rare “double brood emergence” of periodical cicadas is happening in 2024. The last time this happened was in 1803 when Thomas Jefferson was the US president. Read on to learn more!

Week 6 (May 5 to May 11) brought fewer moths into Iowa than the previous week, but cooperators still recorded 135 black cutworm (BCW) moths around the state. Five significant flights occurred last week, adding to the numerous significant flights that have already occurred this season.

Western and northern corn rootworms are serious corn pests in Iowa and the Corn Belt. These pests readily adapt to management tactics, especially in continuous corn production. The larvae consume corn roots, thereby reducing nutrient and water uptake, and cause stalk lodging. The adults may also feed on above-ground parts of the plant, including silks and pollen, which may interfere with pollination.

Last week was another wet week with rainfall totals ranging from just over 0.5 inch to 2.5+ inches of rain across the state. Folks were finally able to get back in fields late last week and over the weekend to do tillage, plant, spray, and even get hay cut and baled or cover crops harvested for feed.

Planting progress started off strong, but recent rain events across the state have brought it to a screeching halt. It seems like fields get just about fit to get back in them to plant and it rains again. According to the May 6^th USDA Crop Progress Report, corn planting was at 47% complete and soybeans at 30% complete, which is 2 days behind both last year and the 5-year average.

With all the alfalfa weevils, we’ve had quite a few questions on how do you know if a field is a threshold to take action? Or I’ve used my sweep net, what’s the threshold per sweep for alfalfa weevil?

First off, a sweep net can be a helpful tool to determine if alfalfa weevils are present in a field.

However, we don’t use a sweep net to determine if action is warranted for management. Instead, stem counts are a more accurate way to help determine if action is warranted.

With the quick planting that happened the week of April 22-26 and the lack of field activity since due to high winds and rain, some fields may have crops emerging that have had no preemergence herbicide. While some herbicides can be applied prior to or after crop emergence, many have restrictions related to applications when crops have emerged. This could mean applicators need to change carrier, adjuvants, or herbicide to avoid crop injury.

Estimating First Crop Alfalfa Harvest using PEAQ

Recent rain events have put a delay on much planting progress and other field activities across the state of Iowa. Planting considerations, alfalfa weevil, cover crop termination, and weed management have been some of the common questions or topics reported by ISU Extension and Outreach field agronomists over the last two weeks. Read on for more specifics on what’s happening in different areas across the state.  

Northwest Iowa

Is it Time to Graze Your Pastures?

For the second year in a row, alfalfa weevil is the most prominent spring pest for farmers. Unprecedented populations south of I-80 have been reported in 2024 and are proving to be much more severe and widespread than in previous years. We are predicting northern Iowa counties to also experience high densities in the next 7-10 days as temperatures warm up. There may be a few reasons for the alfalfa weevil surge: