Integrated Crop Management News

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SCN-resistant soybeans varieties for 2025 including 200 with Peking resistance

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.

What's that Green Carpet Under the Harvested Crop?

Asian copperleaf has lanceolate to egg-shaped leaves with blunt teeth and deep veins.

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.

Is it too late to Spray Soybean Aphids?

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.

Precision Spraying Technology

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.

Consider Your Corn Earworm Management Options for Sweet Corn

Corn earworm is a pest that causes direct injury to corn ears. Corn earworms do not survive winters above the 40^th 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.

Reducing Herbicide Use While Maintaining Crop Yields: Insights from a Crop Rotation Experiment

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.

Repairing Flood-Damaged Farm Fields

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

Hungry Hungry (Grass) Hoppers

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.

Identification and Life Cycle

Have our SCN sorrows been drowned?

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.

Nematodes are worms (animals) that require oxygen. And they absorb oxygen through their body wall or cuticle, which is made almost exclusively of proteins. Waterlogged soils may have greatly reduced levels of oxygen, but many plant-parasitic nematodes, including the soybean cyst nematode (SCN), can survive long periods of time with little oxygen.

Management Guidance for Flooded Grain

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.

Flooding affects both the stored grain and the storage structures.

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