Statewide evaluation of foliar fungicides on soybeans in 2023 in Iowa
By Nabin K. Dangal, Edgar Nieto, Stith Wiggs, Jose Gonzalez-Acuna, and Daren S. Mueller.
By Nabin K. Dangal, Edgar Nieto, Stith Wiggs, Jose Gonzalez-Acuna, and Daren S. Mueller.
Well, I’ll be darned! Yesterday I tweeted the only disease being seen in Iowa corn was common smut on leaves. Thanks to an overzealous crop scout from a seed company, we can confirm that tar spot was observed in central Iowa (Poweshiek, Tama, Marshall, Jasper, Story and Polk counties) yesterday. Last year, this same scout also found tar spot for the first time in Iowa on 30 June. (Does this mean Iowa has the best scouts, I wonder?).
Corn foliar fungicide trials were done at six locations in Iowa in 2022: 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.
Corn foliar fungicide trials done at six locations in Iowa in 2021: 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.
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.
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.
ISU Extension and Outreach and the College of Agriculture and Life Sciences recently hosted a “five-stop” virtual field day series. This series featured a greeting by Dean Dan Robison, an administrative update on the farms, and four consecutive days featuring water quality research, fungicide trials, a long-term tillage trial and phosphorous and potassium placement trials for crop production.
Hailstones damaged corn and soybean in multiple locations across Iowa on July 11, 2020. Fungicide use after hail injury is sometimes suggested as a way to benefit damaged plants. In order to help determine if fungicide use after hail is beneficial, Iowa State University undertook multiple years of research.
To summarize this research on reproductive stage crops:
Now is the time when decisions to apply a foliar fungicide in soybeans are being made. As you are making that decision, this is a quick reminder that fungicide resistance, particularly to the quinone outside inhibitor (QoI) fungicides (FRAC Code 11), has been found to be widespread in Iowa in the pathogen that causes frogeye leaf spot on soybean. See this previous article for additional details.
Iowa State University researchers recently published their annual fungicide trial data for soybeans in 2019, revealing a continued decline in efficiency among the quinone outside inhibitors (QoI) class of fungicides in preventing foliar diseases in soybeans.