Corn Hybrid Response to Foliar Fungicides

• Making farm and field fungicide decisions can be complex.
• To help the decision process, results from this study can help farmers understand hybrid susceptibility to disease and their response to fungicide.

There are many factors that go into making fungicide application decisions. Scouting and timely applications should always be the biggest drivers in the final decision. There are many levels of complexity beyond scouting that go into making farm-by-farm fungicide decisions. The Golden Harvest^® Agronomy in Action research team conducts a yearly study that provides results to better understand the potential of individual hybrids to respond to fungicide treatment. Understanding hybrid susceptibility to a disease is extremely important in fields where disease pressure is highly predictable. It is more challenging to forecast an economic response within fields that rarely have noticeable disease presence.

Estimating Response with Low Disease Presence

Fungicide trials are established each year using Miravis^® Neo fungicide applied at the R1 growth stage to evaluate individual hybrid response (Figure 1). Yield response varied greatly across hybrids and locations based on differing disease environments (Figure 2). The frequency and magnitude of individual hybrid response in lower disease environments was used to categorize hybrids into response categories of Best, Good, Fair and Poor.

Predicting Disease Risk for Each Field

Predicting disease can be difficult. However, timely fungicide applications prior to disease establishment almost always pay off. Selecting hybrids with good disease tolerance and utilizing foliar fungicides are important in areas with high disease risk. The following conditions can put fields at higher risk of disease development:

• Continuous corn rotations
• Reduced tillage fields with high residue levels where pathogens can overwinter
• Extended periods of high humidity and leaf wetness that can favor disease development
• Fields with history of standability issues
• Observations of disease presence across multiple years
• Early signs of disease infection on lower leaves

Benefits Beyond Yield – Stronger Stalks

In addition to disease control and potential yield response benefits, fungicide applications can also help improve standability at time of harvest. Consistent force was applied to multiple stalks, and plants subsiding to the pressure were recorded as a percentage of plants artificially lodging. Multiple hybrids treated with fungicide showed significant reduction of lodging (Graph 1).

The data suggest that utilizing a foliar fungicide can:

• Improve stalk integrity
• Reduce stalk lodging
• Decrease harvest losses
• Reduce harvest time

An additional benefit observed with Miravis Neo is plants stay green longer, helping to extend photosynthesis and grain fill time later into the season. Also, water loss has been found to be reduced in short periods of drought, helping corn better tolerate stress.

Decision Process for Fungicide Application

1. Select the best-suited hybrid for a field based on adaptability, agronomics and relative maturity
2. Determine disease risk potential of field and use appropriate decision tool

Low Disease Fungicide Response

• Utilize “Low Disease Fungicide Response” ratings to understand which hybrids have the best chance of responding in these conditions
• Best or Good indicates the hybrid responded more often and at a greater magnitude
• Fair or Poor indicates responses may be smaller and less consistent

High Disease Fungicide Response

• Utilize “High Disease-Hybrid Susceptibility Rating” specific to disease of concern from chart below to understand which hybrids are more vulnerable to yield loss
• Scout fields and make timely fungicide applications at sight of symptoms, first focusing on most susceptible hybrids. Always follow product labels.

To learn more about factors to consider when deciding on corn fungicide application, watch this video.