Hail damage has recently occurred to corn in Minnesota that was primarily at the V7-9 growth stage. Some producers are asking about the value of applying foliar fungicides to corn damaged by hail. This article will cover key points on this topic and summarize results from field studies.
Why might applying fungicides to hail-damaged corn be beneficial?
A common misconception is that hail damage opens the corn plants to infection and disease that can be controlled with fungicide applications. Few corn diseases in Minnesota are increased by hail damage, with the exception of common smut, Goss’s leaf blight and wilt, and possibly stalk rots. However, none of these diseases are managed effectively with foliar fungicides. In addition, a 3-year study in Iowa found that foliar disease was typically lower in corn plots with simulated hail damage (references #1 and 2). Another replicated study in Illinois also reported no consistent increase in disease in corn plots with simulated hail damage (3). Finally, fungicide applications to vegetative stage corn do not produce a consistent yield response, particularly in the absence of controllable disease.
What does the available data show about the potential value of fungicides applied to corn damaged by hail?
The published results that I have seen indicate no significant benefit to application of fungicides to hail-damaged corn. First, in a replicated study done over two years in Illinois with simulated hail damage, foliar fungicides did not significantly reduce disease or increase yield in corn damaged by simulated hail (3). In another replicated study done with simulated hail damage over three years at three locations in Iowa, foliar fungicides also did not significantly decrease disease or increase yields in plots with different levels of simulated hail damage. Finally, crop consultants and producers have reported to me that when they applied fungicides to corn following hail damage in west central and south central Minnesota, there was no notable decrease in disease or increase in yield with the fungicide applications.
In summary, available evidence suggests that foliar fungicides do not consistently reduce disease or increase yield in hail-damaged corn. However, it is likely that fungicides will be applied this year on some corn fields in Minnesota damaged by hail. We would appreciate if anyone is willing to share their results from field tests so that we can add to our information base on this practice.
#1. Effect of Foliar Fungicides on Hail-damaged Corn. This full article from Iowa has limited access, but a summary of the results are reported in Reference #2 below. (https://www.plantmanagementnetwork.org/php/elements/sum2.aspx?id=10881)
#2. Hail and Fungicide Use on Corn (in Iowa). This is a summary from the study reported in reference #1. (http://crops.extension.iastate.edu/cropnews/2015/06/hail-and-fungicide-use-corn)
#3. Effect of foliar fungicides on corn with simulated hail damage. (http://apsjournals.apsnet.org/doi/pdfplus/10.1094/PDIS-94-1-0083)
Thanks to Bruce Potter for his contributions to this article.