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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.

While planting progressing had occurring in the western and northern part of the state, planters were finally able to roll across much of the entire state starting late last week and over the weekend. In addition to planting, other field activities including spraying and fertilizer applications are also taking place. Some of the first-planted corn and soybeans have now emerged.

Soybean cyst nematode (SCN) is a major yield-reducing soybean pathogen in Iowa, but numbers can drop as much as 50% when nonhost corn is grown. This decrease in egg numbers contributes greatly to overall management of the nematode. SCN reproduces well in greenhouse studies on the winter annual weeds henbit, pennycress, and purple deadnettle.

Between April 20 and April 26, 19 trap sites reported a total of 96 black cutworm moths captured in traps (Figure 1). There were five significant flights during the week (Figure 2), including Buena Vista, Cerro Gordo, and Franklin counties on April 22, and Marshall and Tama counties on April 24.

This past week finally provided a window for most across the state to get into fields and complete some fieldwork. However, that window was short-lived, as rainfall late last week and into early this week brought activity to a halt. Some early-planted crops are now emerging. In addition to weeds getting a good jump start, other pests being reported include slugs in cover crop fields and increasing alfalfa weevil activity.

Iowa State University Extension and Outreach Field Agronomists have completed their spring survey of subsoil moisture in northwest Iowa. Subsoil moisture sampling in Iowa dates to February 1954 when ten sites were chosen for soil moisture sampling. In 1959, the sampling increased to 22 locations, and in 1971, 61 locations were sampled. Today, 18 locations are sampled in northwest Iowa.

Between April 15 and April 19, 18 trap sites reported a total of 42 black cutworm moths captured in traps (Figure 1). During that time, there were no significant flights (Figure 2); however, there was one additional significant flight reported in Polk County on April 13 that was not included in the previous report.

Residual soil nitrogen levels may be higher than average heading into 2026 due to the relatively warm winter, meaning some fields may need less sidedress N fertilizer than in a typical year. The Late Spring Nitrate Test (LSNT) can be used to reduce uncertainty in N fertilizer needs, lowering the risk of both under and over application. 

While the cool, wet conditions across most of Iowa have helped alleviate drought, they have interfered with cover crop (CC) termination ahead of planting. We normally recommend terminating CCs with a herbicide application at least 10 days before planting corn – because corn is a “princess” and there is more risk and potential issues when planted green (i.e. cover crop terminated at or after corn planting).

Planting green is associated with reduced corn yield.

While most areas of the state saw minimal or no field activity this past week, activity continued to progress and pick up in northwest and north‑central Iowa. Pastures, hayfields, and cover crops are showing good growth—but so are the weeds. Below, ISU Extension and Outreach field agronomists share what they’re seeing and hearing across their regions.

Cherokee, Ida, Lyon, Monona, O'Brien, Osceola, Plymouth, Sioux, Woodbury counties

The crop insurance planting dates have come and gone with barely a field planted for many farmers across Iowa in stark contrast to the last two springs. Cooler temperatures in early April and persistent rainfall has prevented much progress, as indicated by the USDA Crop Progress and Condition Report on April 12. Rainfall totals over four inches in the past two weeks for a good swath of the state from southwest to northeast has replenished soil moisture.

Iowa State University Extension and Outreach’s Crops Team reached thousands of farmers, agribusiness professionals and crop advisers during the 2025–2026 winter season through a wide range of educational programs focused on timely crop production issues and decision‑making.

Black cutworm (Agrotis ipsilon) is an occasional pest of corn and soybean in Iowa. This insect cannot overwinter here, so spring storms deliver moths to Iowa each year. Because they are migratory, their occurrence in the state is sporadic, and scouting is essential to determine whether fields require treatment for black cutworm larvae. Trapping for moths is a relatively simple way to understand which regions may be at higher risk and predict when larvae may be active in fields.

Outside of northwest Iowa, which has missed more of the recent rains, field activity across the state has either been limited or brought to a halt due to the wet conditions. With much of the state waiting to get back into the field and get a start on planting, ISU Extension and Outreach field agronomists provide updates on what they are seeing and what’s happening in their respective regions across the state.

A few months ago, we discussed the upcoming 2026 modernization of the U.S. coordinate system and what it could mean for precision agriculture. As the transition date approaches, more details have been released, and it’s time for Iowa growers to start preparing.

In 2026, the National Geodetic Survey (NGS) will officially replace:

Before making pesticide applications this spring, make sure to check areas near fields to prevent off-target pesticide exposure. Herbicide labels often require applicators to consult a sensitive crop registry to identify nearby non-target plants, beehives, or organic farms before application. For example, the dicamba products Engenia, Stryax and Tavium require documentation that the sensitive crop registry was checked.