Fungicide Use on Hail Damaged Corn and Soybean

July 14, 2020 8:38 AM
Blog Post

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:

Corn. Results from a three-year study suggest pyraclostrobin + metconazole application may not provide yield-increasing plant health benefits when applied after a mid-season (VT and R2) hail event when foliar diseases are not present at damaging levels. Results from this study support the claim that economic profitability from fungicide use in corn is more likely if fungicide application is for the purpose of disease management when disease risk is high. However, if you are applying a fungicide after hail injury to mid-season corn, waiting at least a week to apply the fungicide is more beneficial than an immediate application.

Soybean. Research suggests that hail injury at soybean growth stage R1 should not, by itself, be reason enough to make an application of foliar fungicide at R3 when disease risk is low. 

Iowa State University’s hail extension publications include the above information, and can be downloaded for free from the Iowa State University Extension and Outreach Store.

Hail on Corn in Iowa (IPM 0078) at 

Hail on Soybean in Iowa (IPM 0079) at 

Large hailstones in a person's hand from a July 2020 hailstorm
Hailstones from a storm on July 11, 2020 that fell in Story County, IA.

Initial results for hail injury on vegetative stage crops have been summarized previously at ICM News: 


Adam Sisson Extension Specialist

Adam Sisson is an extension specialist with the Iowa State University Integrated Pest Management (IPM) program and a Certified Crop Adviser. Sisson focuses on the development of publications and other educational resources for farmers, agribusi...

Daren Mueller Professor

Daren Mueller is an associate professor and extension plant pathologist at Iowa State University. He is also the coordinator of the Iowa State Integrated Pest Management (IPM) program. Daren received his bachelor's degree from the University of Wisconsin-Madison in 1996, and his master's degree a...

Alison Robertson Professor of Plant Pathology and Microbiology

Dr. Alison Robertson is a professor of plant pathology and microbiology. She provides extension education on the diagnosis and management of corn and soybean diseases. Her research interests include Pythium seedling disease of corn and soybean and Goss's wilt. Dr. Robertson received her bach...