Smart Fungicide Decisions for Corn and Soybean Farming

By Scout Nelson

Crop diseases have become an important concern for farmers in recent years, especially in regions like Nebraska. Before applying fungicides to corn and soybean crops in 2026, farmers must carefully assess multiple factors such as disease presence, weather patterns, and crop growth stages.

In corn, one of the key diseases to watch is the tar spot. This disease is caused by a fungus that survives through winter and can reappear in fields where it existed before. Cool temperatures between 60–70°F and wet conditions favor its growth. Irrigation systems such as center pivots can further increase the risk by raising humidity and keeping leaves wet for longer periods. Early signs of tar spot may appear during the vegetative stages, but experts advise that fungicide application at this stage is usually not economical.

Research shows that applying fungicides between VT to R3 growth stages offers better control and improves returns. Farmers should act before disease severity exceeds five percent on the ear leaf. Using fungicides with multiple active ingredients from different classes can improve effectiveness.

Another disease of concern in corn is southern rust. Unlike tar spots, southern rust does not survive in local fields and depends on spores carried by wind from southern regions. Weather plays a major role in its spread, especially warm temperatures and high humidity. Currently, no outbreaks have been reported, but farmers should remain alert.

For soybean crops, diseases like white mold and frogeye leaf spots can significantly affect yields. White mold poses a higher risk if fields have a history of this disease. Soybeans are most vulnerable during the flowering stage, and fungicide application is most effective around the R2 growth stage.

It is also important to understand that not all soybean diseases can be controlled with fungicides. Conditions such as sudden death syndrome and brown stem rot require proper diagnosis before treatment decisions are made.

Farmers can track disease updates and get further guidance from the Crop Protection Network at https://cropprotectionnetwork.org

In conclusion, proper timing, correct diagnosis, and understanding field conditions are key to making effective fungicide decisions. Careful planning helps reduce costs while protecting crop health and improving farm productivity.

Photo Credit: istock-fotokostic