Integrated Crop Management News
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April 6, 2021Authors
The potential for continued dry weather across the state raises concerns about the impact of dry soils on preemergence herbicides. Preemergence herbicides kill weeds by being absorbed into the seed as the seed imbibes water. To be effective, the herbicide must be located within the soil profile at the depth where weed seeds germinate (primarily the upper inch of soil). In addition, there must be sufficient water to keep the herbicide dissolved in soil water.
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March 10, 2021Authors
If you are planning on conducting field trials this growing season, how you set up the field trial can determine the accuracy of your yield data at harvest. To reap the full benefits of gathering yield data to improve crop management and influence input decisions, it should be part of your management plan year-round.
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February 17, 2021Authors
This article summarizes 2020 corn foliar fungicide trials that were done at six locations in Iowa: ISU Northwest Research and Demonstration Farm (NWRF), Sutherland; Northeast Research and Demonstration Farm (NERF), Nashua; Northern Research and Demonstration Farm (NRF), Kanawha; Southwest Research and Demonstration Farm (SWRF), Lewis; Southeast Research and Demonstration Farm (SERF), Crawfordsville; and the Ag Engineering and Agronomy Farm (AEA) near Boone.
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February 11, 2021Authors
Marestail is one of the most widespread and troublesome weeds in Iowa croplands. It can grow to a height of 1.5 to 6 feet, produce up to 200,000 seeds, and can reduce soybean yields up to 80% if not controlled (Figure 1). Marestail seeds are light and disperse across landscapes with winds. Seeds have little dormancy and can germinate soon after seed shed.
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January 11, 2021Authors
Iowa State University has evaluated the nematode control and yield performance of soybean varieties that are resistant to the soybean cyst nematode (SCN) in hundreds of experiments conducted over nearly three decades. The results of the 2020 experiments are now available and are highlighted in this article.
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January 10, 2021Authors
Each year, the ISU Soybean Research Laboratory conducts insecticide efficacy evaluations for soybean aphid, and two emerging pests, Japanese beetle and soybean gall midge, were added in 2019. Details about pest biology, research plot design, sampling methods, and additional results can be found here.
Soybean aphid
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January 5, 2021Authors
Waterhemp is a dioecious (male and female flowers on separate plants) pigweed with a high genetic diversity. Consequently, this pigweed has a high propensity to adapt to control tactics and has evolved resistance to herbicides from as many as 6 or 7 different herbicide groups (HGs).
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December 7, 2020Authors
There are hundreds of soybean varieties with resistance against the soybean cyst nematode (SCN). Most of the varieties available for Iowa in the last several decades have had resistance genes from a breeding line called PI 88788. SCN resistance from PI 88788 is losing or has lost its effectiveness. Farmers should grow soybean varieties with other sources of resistance, if possible. This article lists soybean varieties available for 2021 in Iowa with resistance sources that are different from PI 88788.
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December 2, 2020Authors
With support from the soybean checkoff through the United Soybean Board, Iowa State University researchers evaluated foliar fungicides on soybean in 2020. Because dry weather affected all seven field locations, this year was really an evaluation of fungicides largely in the absence of disease. Seventeen fungicides were tested at the R3 (beginning pod) growth stage, at the recommended label rate.
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November 23, 2020Authors
Resistant soybean varieties are critical for managing the soybean cyst nematode (SCN). There are nearly 850 SCN-resistant varieties in a newly updated publication from extension. Almost all of the varieties have the breeding line PI 88788 as the genetic source of resistance. Many SCN populations in Iowa now have high levels of reproduction on varieties with this resistance. Only 39 varieties in the new publication have resistance genetics from a source other than PI 88788. This article discusses the range of SCN-resistant varieties available and includes recommendations for using resistant varieties to manage SCN most effectively.
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October 19, 2020Authors
The dry, warmer-than-normal growing season this year presents significant challenges for managing soil and crop residue this fall.
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October 14, 2020Authors
Sampling soil this fall following the dry conditions this past summer, and in some places continuing up to this time, may result in lower than expected soil-test results for phosphorus (P), potassium (K), and pH. Especially if soil samples are collected before any significant rainfall. Therefore, farmers and crop consultants should interpret those soil-test results with caution.
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October 7, 2020Authors
Fall is an ideal time to collect soil cores from fields to determine if the soybean cyst nematode (SCN) is present and to assess the population densities (numbers). There are reasons to sample fields in which soybeans and corn were grown in 2020. Multiple private soil testing laboratories can process samples for SCN as can the ISU Plant and Insect Diagnostic Clinic. Guidelines for fall SCN soil samples are provided in this article.
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September 10, 2020Authors
Wind damage or stalk rots can cause lodged corn that is difficult to gather with standard corn harvesting equipment. Powered attachments for corn heads are available to assist the gathering process and reduce the number of missed stalks and ears. These attachments assist the flow of corn stalks up and over the snouts and into the gathering chains and cross augers.
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September 10, 2020Authors
A monitoring network was established this year to monitor corn rootworm adults in Iowa cornfields, similar to the moth trapping network we manage in the spring each year. The goal was to help farmers and agronomic professionals monitor populations of northern corn rootworm (NCR) and western corn rootworm (WCR) in their fields and assess management decisions. A secondary goal was to estimate the ratio of NCR to WCR throughout the state and describe changing ratios into the future.
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September 9, 2020Authors
The August 10 derecho left portions of Iowa with broken, uprooted, and damaged corn across a significant portion of the state.
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September 9, 2020Authors
The majority of Iowa is currently in moderate to severe drought, with west central Iowa under the most extreme drought. As if drought were not enough, we were dealt another blow with extreme and widespread wind damage on August 10, some of which overlapped the drought area. With these events come an increased risk for ear rots and associated mycotoxins.
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September 9, 2020Authors
The Derecho storm on August 10 left fields with varying degrees of downed corn. In the weeks following the storm, the condition of the corn plants has worsened and the quality of the corn grain appears to be deteriorating. This deterioration in quality is expected to increase with time.
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September 3, 2020Authors
The dry conditions throughout large areas of Iowa during 2020 reminds us of Iowa’s last significant drought in 2012 and the subsequent impacts on nitrate-N levels in subsurface drainage the following spring. This article will address concerns for water quality in drought conditions and opportunities to reduce nutrient losses from fields this fall.
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August 27, 2020Authors
Many fields have been ravaged by adverse weather this year in Iowa. On top of drought and hail we had a devastating derecho steam-roll a wide swath of Iowa starting in Sac County and progressing eastward along Highway 30. Along with the decision of how to handle this year’s crop, consideration for protecting the soil and preparing for next year’s crop should include cover crops.