Integrated Crop Management News

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Considerations when Overseeding Cover Crops

July 13, 2021

In the last decade, cover crops have grown in both interest and acres, yet there is still room for more adoption across Iowa and the region. It is obvious that cover crops require more management though and with that management there will undoubtedly be challenges. In just a few weeks the cycle for cover crop establishment, growth and termination will begin.

Nitrogen Deficient Soybean with Excess Soil Moisture

July 13, 2021

Rainfall has been extremely variable this season in Iowa. There has been severe drought in many areas of Iowa. In contrast, rainfall has been excessive in some areas of southeast and southern Iowa. Soybean with poor growth with pale green or yellowish color has been observed in low-laying fields or field depressions with poor drainage and frequent waterlogged soils since May.

Thinking of Plant Tissue Testing this Season? Beware of Drought or Excess Moisture Effects

July 9, 2021

Corn tassels began showing in some Iowa fields this past week and in the next week corn in most fields will be at the R1 stage (silking). Most soybean fields are at R2 or will be at the R2 to R3 growth stage soon. Nutrient concentrations vary greatly with crop growth stage and plant part sampled. Calibrations of tissue tests based on field response trials for corn and soybean in Iowa and other states have been for leaves at the R1 growth stage in corn and the R2 to R3 growth stage in soybean.

Soybean Gall Midge Adult Emergence Beginning in Iowa

June 17, 2021

This week, the first adult soybean gall midges (Photo 1) were collected in Iowa and Minnesota. Thanks to Lauren Schwarck (Corteva Agriscience) for monitoring several emergence traps this year. The positive detections were located in Buena Vista County, an area with persistent soybean gall midge populations since at least 2017.

Corn Rootworm Egg Hatch Peaking in Iowa

June 14, 2021

Corn rootworm egg hatch in Iowa occurs from late May to the middle of June, with an average peak hatching date of June 6 in central Iowa. Even with recent warm temperatures, hatching is a bit delayed this year due to cool spring temperatures. 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 in Iowa will reach peak corn rootworm egg hatch within a week (Figure 1).

SCN in Iowa: A Serious Problem that Warrants Renewed Attention

June 11, 2021

The soybean cyst nematode (SCN) is the most damaging pathogen of soybeans in the United States. Farmers in Iowa successfully managed SCN for many years by growing SCN-resistant soybeans in rotation with corn. However, almost all resistant varieties contain SCN resistance genes from the same breeding line, named PI 88788. Not surprisingly, SCN populations in fields throughout the state are overcoming the PI 88788 resistance because of use of those resistance genes for more than 30 years.

What causes striped corn leaves?

June 11, 2021

Iowa State University (ISU) Extension and Outreach field agronomists have been receiving phone calls and texts about striped corn leaves this past week. There are many reasons for striped corn, and the cause of light green, whitish, or yellowish stripes sometimes is not obvious. Here is a review of some of the reasons for striped corn and also methods to distinguish what might be causing the stripes. 

Genetic Striping

Japanese Beetle Adult Emergence Beginning in Southern Iowa

June 11, 2021

This spring, we have had several reports of fields with high numbers of grubs from field agronomists in central Iowa. There are multiple species of white grubs in Iowa, including the Japanese beetle. Recent warm temperatures are accelerating insect development, and with forecasted temperatures, Japanese beetle emergence could begin in southern Iowa counties this week (Figure 1). Japanese beetle adults will 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.

Stalk Borers are on the Move Across Iowa

June 8, 2021

Stalk borer is an occasional pest of corn, but it can be persistent in some fields, especially those fields near fence rows, terraces, and waterways that serve as overwintering sites. Tracking degree days is a useful tool to estimate when common stalk borer larvae begin moving into cornfields from their overwintering hosts. Foliar insecticide applications are only effective when larvae are migrating and exposed to the insecticide. Start scouting corn for larvae when 1,300-1,400 degree days (base 41°F) have accumulated.

Fomesafen Carryover to Corn

June 8, 2021

ISU Extension and Outreach Field Agronomists recently highlighted a significant number of phone calls related to fomesafen carryover injury to corn rotated from 2020 soybeans.