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If you have been out in the field checking stand or doing early-season scouting for weeds, diseases, and insects, you might be noticing that insect activity is picking up across the state. We are approximately 200 growing degree days ahead of schedule this spring, which means insect development is happening quickly for insects that overwintered or arrived here with strong storm systems.

The trapping season for black cutworm has come to an end. We appreciate our cooperators for tirelessly checking traps the last two months and reporting their captures so we can provide the most accurate scouting information for these pests. To recap, we had 15 volunteers participate from 18 counties in Iowa. A total of 22 black cutworm traps were placed and monitored during April and May.

Crops have really started to take off with the warmer temperatures, though growth stages vary depending on planting date. Over the past week, field activity has been strong across the state, including postemergence herbicide applications, sidedressing, planting and/or replanting, and first-cutting hay being put up. For more specific updates on crop conditions and regional activity around the state, Extension field agronomists share insights below

With Spring here and crop stands beginning to grow, it is time to shift focus to the next operation of the 2026 growing season: spraying. These operations are "make or break" for crop health, whether you are applying weed control, warding off insects, or managing bacteria and fungus. While these operations require financial and time investments, performing proper maintenance and calibrations directly impacts success rates and your ultimate return on investment.

This summer, Iowa State University’s Research and Demonstration Farms are once again hosting a series of field days across the state. These events offer a valuable opportunity to learn about the latest crop production research, management practices, and emerging agricultural technologies directly from Iowa State specialists and researchers.

Residual soil nitrogen levels last year were relatively high and extremely variable from field to field. That means the Late Spring Nitrate Test (LSNT) can generate a large return on investment for in-season nitrogen decision-making this year. For those making in-season nitrogen applications, there may be significant opportunity for savings on fertilizer inputs.

With the recent dry conditions and highly variable forecasted chances for rainfall for parts of Iowa just as postemergence herbicide applications begin, questions often come up regarding use of residual herbicides and efficacy of postemergence applications during these conditions. 

Between May 18 and May 24, 16 trap sites reported a total of 73 black cutworm moths captured in traps (Figure 1). There was a significant flight reported in Franklin County on May 18 (Figure 2).

Using historical temperature data from the Midwest Regional Climate Center database, Table 1 shows the current projected cutting dates in counties that have had a significant flight. 

Over the past couple of weeks, many soybean fields have experienced challenging conditions from soil crusting shortly after planting to more recent hail events. The result has been uneven emergence, and, in some cases, plant populations are below what was originally targeted. As conversations turn to replanting decisions, it is important to remember that soybeans have a remarkable ability to compensate for reduced plant populations.

Between May 11 and May 17, 19 trap sites reported a total of 74 black cutworm moths captured in traps (Figure 1). There were significant flights reported in Plymouth and Tama counties on May 17 (Figure 2).

Using historical temperature data from the Midwest Regional Climate Center database, Table 1 shows the current projected cutting dates in counties that have had a significant flight. 

Across Iowa, planting is nearing completion or has wrapped up. There have been some emergence concerns in fields across the state due to soil crusting. The rain over the weekend and early this week will hopefully help alleviate that, but unfortunately there were areas that also experienced heavy rainfall, hail, strong winds, and tornados. ISU Extension and Outreach field agronomists share more specifics about what’s happening in fields around the state. 

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.

Between May 4 and May 10, 19 trap sites reported a total of 39 black cutworm moths captured in traps (Figure 1). There were no additional significant flights during the week (Figure 2).

Using historical temperature data from the Midwest Regional Climate Center database, Table 1 shows the current projected cutting dates in counties that have had a significant flight. 

Over the last week, there was a lot of field activity across the state—planting, spraying, rotary hoeing, and fertilizer applications. Early planted corn and soybean fields have emerged, but there are concerns about soil crusting impacting emergence and stands. Insect activity is starting to increase, with reports of alfalfa weevil larvae and cutworms.

Early-season field conditions can set the tone for the entire growing season. Two common soil issues that can limit early crop development are soil crusting and sidewall compaction. While they look different in the field, both restrict crop establishment and early root growth, reduce early vigor, and can make crop stress symptoms show up sooner and more severely.

“Cutworm” is a common name for many caterpillars in the moth family Noctuidae. They are insects (not worms!) that chew, or cut through, plants above or below the soil line in the spring. One notable exception is the western bean cutworm, which occurs later in the season and targets reproductive tissues rather than cutting stems.

The Iowa State University Extension and Outreach Crops Team is seeking sponsors for our upcoming winter programs. These programs include the Integrated Crop Management Conference (ICM), the Crop Advantage Series, Planter U, and CropsTV. Each year the Crops Team reaches over 2,000 contacts through events like these. 

The hot-and-cold temperatures this spring have delayed alfalfa weevil development throughout the state. We visited a field in Henry County, IA this week and noticed all sizes of larvae plus pupae. Take a sweep net to the field to see what's happening in your alfalfa fields. Also, note aphids and other potential pests. Sometimes, mechanical control (mowing) may be the most economical management tool. 

Between April 27 and May 3, 19 trap sites reported a total of 99 black cutworm moths captured in traps (Figure 1). There were two significant flights during the week (Figure 2), including Washington County on April 26 and Jackson County on April 28.