16 Jul 2020
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Fungicide - When Should It Be Applied?

With 29% of the nations corn crop in the silk growth stage according to the latest USDA crop progress report and 69% of the corn crop rated G/E many of the questions I have been receiving over the last two weeks have focused around fungicide applications in corn. Should I use a fungicide? What response level can I expect out of each hybrid? What is our disease pressure? When should I apply fungicide? 

corn crop condition

What to Consider

The most important factor at the end of the day when considering a fungicide application is economics and ROI. Will my investment of fungicide and application costs yield enough return to return a positive ROI?   We know that each hybrid has different levels of response to fungicides, last year locally in SW MN our fungicide trials had a range of +23 bushel/acre response to -2 bushel/acre response, with the average being an 8 bushel/acre response. Results like that allow us to easily identify which hybrids are going to have an economical response the majority of the time to a fungicide application and which hybrids have an agronomic package that does not benefit from a fungicide application unless severe disease pressure exists. Hybrids that responded closer to the average require a deeper look into the local environment they are placed in and need to be evaluated on a field by field basis to determine if a fungicide application will be profitable

Will a fungicide application be profitable? 

  • Scout: Identifying disease pressure is a good place to start, as we reach VT/R1 areGLS you noticing any diseases moving into the corn canopy and what level of pressure are you seeing
  • Previous Crop/residue: pathogens need a host, corn on corn situations will favor disease development and high amounts of residue play host to disease.
  • Weather Past/Current: Utilize the Advantage Acre 4-week weather forecast for insights into what the NCLBpotential for disease pressure may be. Wet weather favors disease development and temperatures influence what diseases develop. Warm temps (80+ degrees F) favor Gray Leaf Spot development and moderate temps (64-81 degrees F) favor Northern Corn Leaf Blight  
weatherscreenshot

Timing a fungicide application for VT-R1 continues to show the biggest bushel gains of any application window. Other benefits to keep in mind of a fungicide application are improved stalk integrity and harvestability at the end of the growing season. These need to be considered as well when making a targeted decision on whether to apply fungicides to specific hybrids.

LG Seeds has fungicide response ratings for each of its hybrid and your local team haseven deeper insights into how a product will respond to fungicide within your local geography. Reach out to them or your STAR Partner with any questions about fungicide applications