As crops move into key reproductive stages, many growers begin asking the same question: Is fungicide worth the investment this year?
A fungicide application is typically the last decision that is made throughout the growing season and the last chance we have to influence the crop and protect the bushels we have.
While fungicides can be a highly effective tool for protecting yield, the response can vary. Yield potential, disease pressure, weather conditions, hybrid or variety planted and crop stage can all influence the response of an application.
Factors That Increase Response
Fungicide applications tend to provide the greatest return when several conditions align:
● Favorable yield potential
● Weather conditions that favor disease development
● Proper application timing
● Hybrids or varieties with weaker disease ratings
● A history of disease pressure
Fields with strong yield potential generally have more bushels to protect, making fungicide investments easier to justify.
Current Disease Pressure
Disease pressure can vary significantly from year to year and even field to field. Common diseases to monitor include:
Corn
● Gray Leaf Spot
● Northern Corn Leaf Blight
● Tar Spot
● Southern Rust
● Common Rust
Soybeans
● Septoria Brown Spot
● Frogeye Leaf Spot
● White Mold
The presence of disease nearby, combined with favorable environmental conditions, can increase risk and improve the likelihood of a positive fungicide response.
Weather Can Change the Equation
Many fungal diseases thrive under warm, humid conditions.
Extended periods of:
● High humidity
● Frequent rainfall
● Heavy dews
● Dense crop canopies
can create ideal environments for disease development.
Monitoring weather patterns throughout the growing season helps determine whether risk is increasing as crops approach critical growth stages.
Protecting Yield During Reproductive Stages
Timing is one of the most important factors in fungicide performance.
For corn, fungicide applications are often targeted at VT to R1 (tasseling to silking). This is a critical period for pollination and grain fill. Protecting the plant can help preserve photosynthetic capacity when the crop needs it most.
For soybeans, applications are typically made at R3 (beginning pod). At this stage, protecting plant health can help support pod retention, pod development and lead to maximizing yield potential.
These growth stages often provide the best opportunity to protect yield when disease risk is present.
Making the Right Decision
While there are several fungicides out in the market today, not all of them are created equally. It’s important to know what you’re getting when you select a fungicide and manage expectations accordingly.
● How many modes of action?
● How long is it providing protection for?
● Which diseases is it protecting against?
While all fungicides may have a time and place, typically a premium fungicide will provide more consistent results and provide a better return. The benefits are:
● Broader spectrum of disease control
● Longer lasting protection
● Multiple modes of action
● Newer technology
If you’d like help evaluating disease pressure, crop stage, application timing, or selecting a fungicide contact your local Central United agronomist. We’re here to help you protect yield potential and make informed decisions throughout the growing season.