Integrated Crop Management News

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Yellow soybean too early this season?

August 12, 2021

Since early August Iowa farmers have been reporting soybean fields or parts of fields with yellow or greenish-yellow leaves in the upper canopy which resemble early senescence and sometimes nitrogen (N) deficiency symptoms. The soybean growth stage is mainly R4 to R5. Several factors can cause these symptoms. Rainfall has been extremely variable this season in Iowa, with severe drought still persisting in some areas of the state. Yet, areas in southern and southeast Iowa have experienced normal to excessive rainfall.

Twospotted spider mite scouting reminders

July 28, 2021
Two twospotted spider mites on a soybean leaf

Twospotted spider mites have been spotted in fields across much of Iowa already this summer, as much of Iowa is in moderate or severe drought (D1-D2, US Drought Monitor). I encourage you to scout for twospotted spider mites in crops. Twospotted spider mites can increase whenever temperatures are greater than 85°F, humidity is less than 90 percent, and moisture levels are low.

Tips for Late Summer Establishment of Forages

July 21, 2021

Mother Nature doesn’t always cooperate in the spring during the window for seeding forages. Thus, spring seeding may not have happened or stand establishment may be less than desired. Late summer provides an opportunity to establish forages or interseed into poor stands, assuming moisture is available. The recent rains may have some thinking about this, so below are some tips to consider helping a late summer seeding of forages be successful.   

Plan now

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.

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