Integrated Crop Management News
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April 10, 2025As temperatures warm up, the questions are already rolling in from inquisitive folks wondering how insects fared the winter in Iowa. Some insects have adapted to survive freezing temperatures. A prior article delves deep into the topic of “How do insects survive the winter?” and is worth reading for more information on general strategies.
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April 7, 2025Authors
2024 marked the fifth year of a coordinated effort to monitor corn rootworm adults across Iowa and the fourth year of combining this effort with the Regional Corn Rootworm Monitoring Network. The Hodgson Lab receives funding from the Agricultural Biotechnology Stewardship Technical Committee to distribute traps to farmers across corn-growing regions in the U.S. and Canada. The 2024 Regional Corn Rootworm Monitoring Network Summary is now available and this article summarizes the Iowa results.
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April 1, 2025Authors
With above average temperatures this year, alfalfa weevil development is well ahead of schedule compared to recent years. Adults have already emerged from their overwintering sites to lay eggs in alfalfa stems throughout the southern half of Iowa.
Adult alfalfa weevils become active and start laying eggs when temperatures exceed 48°F. Alfalfa weevil egg hatching begins when 200-300 growing degree days (GDD; base 48°F) have accumulated since January 1. Based on accumulated GDD, alfalfa weevils are active throughout southern Iowa and are likely active in other areas as well (Figure 1). You can track GDD for alfalfa weevil by visiting the Pest Maps and Forecasting page and comparing benchmark GDD to the map. Additionally, if you choose the nearest weather station on the right side of the page, you can see forecasted GDD for your area for the next two weeks.
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March 31, 2025Authors
Seedcorn maggot larvae feed on germinating seeds or seedlings of corn and soybean (Photo 1). Feeding can slow development or kill the plant, and plant injury is more prevalent during cool, wet springs when plants grow slowly. With planting right around the corner, we recommend that farmers track growing degree days, plant during the fly-free period, and avoid planting into cool, wet soils, especially in fields at high risk for injury. High-risk fields include those with a history of seedcorn maggot injury, recently tilled fields, and fields where organic matter was recently incorporated (e.g., manure or cover crops).
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March 4, 2025Authors
As temperatures begin to increase following winter, we are entering a period of warm days and cold nights. These conditions result in our soils going through freeze thaw cycles, which make for a perfect time for frost seeding. Frost seeding involves strategically broadcasting or overseeding legumes into pastures, hayfields, or small grains. It is a potentially cost-effective solution to revitalize a diminishing stand or introduce new legumes. However, success hinges upon assessment of the existing stand, proper timing and soil conditions.
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October 24, 2024Authors
Growing resistant soybean varieties is critical to achieving and maintaining profitable soybean yields in fields infested with the soybean cyst nematode (SCN). Information about SCN-resistant soybean varieties in maturity groups 0-3 available for use in Iowa is compiled annually in ISU Extension publication CROP1649. The newly updated publication lists 920 SCN-resistant soybean varieties from 33 brands offered by 25 companies. This article contains information about the varieties, their genetic sources of resistance, and several other important attributes of the varieties.
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September 11, 2024Authors
As corn and soybean are taken out of fields, some fields may reveal an unexpected mat of Asian copperleaf lurking below the canopy. As of this summer, we’ve identified Asian copperleaf (Acalypha australis) in crop fields in eight counties: Calhoun, Humboldt, Boone, Wright, Franklin, Hardin, Grundy, and Black Hawk. Early identification of this species is key to adopting effective management tactics to reduce its spread to other fields.
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August 26, 2024Authors
Soybean aphid is still the most important insect pest of soybean in Iowa, despite low populations throughout the state in recent years. This summer, we have seen high populations throughout Iowa, with hundreds of aphids per plant, honeydew, and sooty mold development on leaves. We have also heard various reports about performance issues with pyrethroid applications. This has prompted many questions about when to spray soybean aphids and which insecticides to use.
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August 22, 2024Authors
Key Points:
Precision spray technology is available in the ag marketplace to provide selective post-emergence herbicide applications. Iowa State University conducted a field scale demonstration of a commercial precision spray system on five conventionally managed soybean fields totaling 415 acres. Herbicide savings per field was 90.6%, 87.6%, 87.2%, 71.2%, and 43.9% respectively. Herbicide savings were directly influenced by the initial weed pressure in the field. Average product savings across all fields was 76% and had an economic savings of nearly $6,500 ($15.7/ac) from reduced herbicide use. -
August 19, 2024Authors
Corn earworm is a pest that causes direct injury to corn ears. Corn earworms do not survive winters above the 40th parallel but some migrate north to the Corn Belt every year. Economic injury in field corn is uncommon due to the high adoption rate of Bt traits in Iowa (e.g. Cry1Ab, Cry1F, Cry1A.105+Cry2Ab2, Vip3A). However, non-Bt sweet corn and popcorn is at risk every growing season, and the financial impact in these specialty crops is especially important.
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August 2, 2024Authors
Weed communities in three cropping systems suitable for the Midwestern USA were studied from 2017 through 2020 to examine how crop diversification and the intensity of herbicide use affected weed stand density and aboveground mass. A baseline 2-year cropping system with corn and soybean grown in alternate years was diversified with cool-season crops, namely oat and red clover in a 3-year system, and with oat and alfalfa in a 4-year system. Herbicides were not used in the cool-season crops.
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July 30, 2024Authors
Farm fields that have been covered with flood waters may need structural (physical) repair before returning to full production. Flood debris, sand, silt, erosion, and loss of soil structure may all result as residual effects of flooding.
Before You Begin
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July 29, 2024Authors
Grasshopper activity in field crops has picked up recently, and these jumpy insects and their defoliation have caught the attention of crop scouts and agronomists across the state. Grasshoppers tend to thrive under dry conditions, and although most areas have received adequate moisture in 2024, consecutive drought years have likely led to higher than usual populations. This article discusses identification, scouting and management of grasshoppers in corn and soybeans.
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June 28, 2024Authors
Those looking for any bit of good news among all the rain-soaked suffering we have endured this growing season have asked if the overabundance of moisture has drowned SCN. Unfortunately, the answer is no.
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June 28, 2024Authors
AMES, Iowa – Extreme rains in northwest Iowa have caused instances of stored grain being covered with floodwater. According to current Food and Drug Administration policy, grain inundated by uncontrolled river or stream water is considered adulterated and must be destroyed. The current situation is one of river water flooding rather than of rain-driven pooled water in low ground, for which there are salvage options. River-based floodwaters can bring in many hazards and rapid spoilage.
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June 24, 2024Authors
The spring has certainly looked a little different than previous years. What does it mean for disease development? With some of our more destructive diseases – sudden death syndrome (SDS) and white mold – the rains have certainly increased the chances of disease developing. Each season these diseases have two hurdles to clear: early season conditions that set up the disease, and mid to late-season conditions that make a disease situation worse.
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June 20, 2024Authors
Corn rootworm egg hatch in Iowa typically occurs from late May to the middle of June, with an average peak hatching date of June 6 in central Iowa. Development is driven by soil temperature and measured by growing degree days (GDDs). Research suggests about 50% of egg hatch occurs between 684-767 accumulated GDDs (since January 1; base 52°F, soil). Most areas within Iowa have reached peak egg hatch for corn rootworm (Figure 1), and we have heard several reports of larvae in cornfields.
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June 19, 2024Authors
Plant-parasitic nematodes that feed on corn are relatively common in Iowa. But their mere presence in soils does not mean that damage and yield loss are occurring. Symptoms of damage include stunting and yellowing of leaves. This article explains how to sample corn fields to determine if nematodes are causing damage and are likely to reduce corn yields.
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June 13, 2024Authors
Japanese beetle development seems to be a bit ahead of schedule this year, which is not surprising with the warm temperatures this spring. Japanese beetle adults begin emergence when approximately 1,030 growing degree days (GDD; base 50°F) have accumulated since January 1 and will continue emerging until 2,150 GDD have accumulated.
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June 11, 2024Authors
The moment a soybean field is planted, the clock starts ticking on when the first SCN females of the year will become apparent on roots. These females normally can be seen about four weeks after planting. For Iowa this season, the first SCN females will begin appearing over many weeks in June and possibly early July for very late planted soybeans. This article reviews tips on how to look for SCN females on roots and what to do when they are found.