Response to Fungicide

Jan 15, 2023

It is time to start planning for summer fungicide applications. Corn hybrids have a Response To Fungicide (RTF) score. While we are preparing for planting, it is important to remember which hybrids are planted in each field to go back and look at each field with a high RTF score to be certain that we are getting these hybrids treated with a good fungicide. We also need to remember the hybrids with a moderate to low RTF score and scout them for disease pressure throughout the summer months, and base decisions on findings in the field.

RTF score and scouting have been good tools to use in the past and still are good indicators of needing fungicide on all diseases except tar spot. Tar spot has been found in many of the areas we are working in, and is going to give us a new perspective and a new look at applying fungicide on corn. Fungicide is the best way to prevent tar spot on corn. Many hybrids claim to be more tolerant than others, but this is a relatively new disease and a lot of unknowns are still out on tar spot. The one thing that is known that fungicide applied prior to tar spot infecting corn is good at reducing the severity of the disease.  However, it takes a couple of weeks for any visual signs of tar spot to show up after infection which makes treating difficult as there is a large period the plant is infected but has no visual signs. 

Soybeans are a little easier to work with on whether to apply a fungicide. Past trials almost always show a return on investment when applying fungicide and insecticide. Fungicide and insecticide applied together have a synergistic effect which compounds your return on investment putting more money in your pocket, giving you a competitive edge over your neighbor. 

We have a good supply of fungicide available at this time, but be sure to get yours locked in to guarantee the product of choice. Talk to your local SFG agronomist and finalize your plans for summer applications of fungicides on your farm. While applying these fungicides it may also be a good time to add foliar N to corn or micros to either crop.