Each year the members of the Corn Disease Working Group and the North Central Regional Committee on Soybean Diseases (NCERA 127) with the support of the United Soybean Board establish ratings on the efficacy of fungicides for corn and soybean diseases. These ratings are intended to provide guidelines on efficacy of the various products for use in corn and soybean. The fungicide active ingredients listed were tested over multiple years and locations by the members of these groups. The tables are updated annually and include the most widely marketed products, but are not an exhaustive list.
The publications are available at the following links:
2020 Fungicide Efficacy for Control of Corn Diseases
2020 Fungicide Efficacy for Control of Soybean Foliar Diseases
2020 Fungicide Efficacy for Control of Soybean Seedling Diseases
They can also be found under Crop Protection Network Resources https://cropprotectionnetwork.org/resources/publications
A new addition this year is product efficacy for tar spot of corn. Fungicide timing is going to be extremely important for tar spot and needs to be made near the onset of the first tar spot symptoms. The efficacy data for this disease was based on limited site locations from 2018 and 2019 and products will continue to be evaluated. In addition, a number of the fungicides have a 2ee label for tar spot, so it will be important to check if your state has this label for use.
Indiana specific data on the management of tar spot is also available in the Purdue Extension publication – Applied Research in Field Crop Pathology for Indiana – 2019
Indiana field crop disease updates and maps for the 2020 season will be available on the Purdue Field Crop Pathology Website https://extension.purdue.edu/fieldcroppathology/.
https://extension.purdue.edu/fieldcroppathology/
