Integrated Crop Management News

Links to these articles are strongly encouraged. Articles may be republished without further permission if published as written and if credit is given to the author, Integrated Crop Management News, and Iowa State University Extension and Outreach. If articles are used in any other manner, permission from the author is required.

Frogeye Leaf Spot Fungicide Resistance Confirmed in Iowa Soybean

February 19, 2018
Frogeye leaf spot is a common foliar disease in Iowa, appearing as gray lesions surrounded by a reddish-brown border on soybean leaves.

Plant pathologists at Iowa State University and University of Kentucky have confirmed that isolates of Cercospora sojina, the pathogen that causes frogeye leaf spot of soybean, have shown resistance to quinone outside inhibitor (QoI, strobilurin) fungicides in Iowa.

Should We be Spraying Fungicides on Corn at V12?

February 8, 2018
graph of humidity at ISU research farms

In 2017, we tested several foliar fungicides on corn 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 (AEA) Farm, Boone.

Downwind Buffers and Susceptible Crop Restrictions for New Dicamba Products

January 13, 2018
dicamba spraying diagram

In response to problems with off-target movement and injury associated with dicamba applications on dicamba-resistant (Xtend) soybean, the EPA made significant changes to labels of the new dicamba products.  While much of the discussion has focused on the Restricted Use designation and the requirement for applicators to receive dicamba-specific training, the EPA also clarified how downwind buffers and protections of susceptible crops are to be implemented.

New Dicamba Labels Issued

January 10, 2018

In October 2017, the Environmental Protection Agency reclassified Engenia®, FeXapan™ herbicide Plus VaporGrip® Technology, and Xtendimax® With VaporGrip® Technology as Restricted Use products and added additional restrictions and requirements to their use. One of the additional requirements stated that anyone wishing to apply these products must attend a dicamba or auxin-specific training.

Crop Quality Management for Harvest 2017

December 6, 2017
maximum storage time table

Corn and soybean yields in 2017 were better than expected, which will add to the largest grain surpluses in recent years. As of the November 9, 2017 USDA crop production estimates, national corn yield estimates exceeded 2016 production and were closer to 2016 production in Iowa than preharvest expectations. Soybean yields are estimated to be lower than in the record year of 2016, but total US supply will be larger due to acreage increases.

Over 1,000 SCN-Resistant Soybean Varieties - All but 29 Have PI 88788 Resistance

November 3, 2017
graph showing SCN resistant soybean varieties

Iowa State just released its annually updated list of SCN-resistant soybean varieties online. There are more than 1,000 different named varieties from which to pick. Unfortunately, 973 of the varieties have the same source of resistance genes, on which Iowa SCN populations have built up increased ability to reproduce.

Know Your SCN Numbers

October 28, 2017
sampling area

Now more than ever, farmers need to know if their fields are infested with SCN and at what levels, especially for fields in which soybeans will be grown in 2018. This article explains why and how to determine SCN numbers in fields.

New Dicamba Labels Limit Application Timing

October 25, 2017
graph showing available spraying hours per day

The EPA recently announced changes to the new dicamba labels in response to widespread off-target plant injury in 2017.  The most significant change is classification of the new dicamba formulations as Restricted Use Products. Other changes will reduce the hours available to spray soybean, including 1) restricting applications to between sunrise and sunset, and 2) reducing the maximum wind speed during application from 15 mph to 10 mph. The ability to cover all acres in a timely manner has always been an issue and these new limits will add to that difficulty.

Sampling for Nematodes that Feed on Corn Not Advised in the Fall

October 21, 2017
small corn seedling lying on shovel blade, collected to test for damaging levels of nematodes

Recently there have been many questions about how to check fields for plant-parasitic nematodes that can damage corn. Unfortunately, the situation cannot be accurately assessed with samples collected in the fall. This article discusses when and how to sample for plant-parasitic nematodes that feed on corn.

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