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.
Integrated Crop Management News
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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.
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.
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.
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.
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.
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.
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.
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.