Corn Seed Product Yield Response to Fungicide Application - DEKALB® - CO KS MO

Trial Overview

  • The impact of a fungicide application on corn yield can be influenced by several factors including seed product disease tolerance and existing disease pressure.
  • This study was established to determine the yield response of fungicide application on six DEKALB® corn seed products.

Research Objective

  • Evaluate corn seed products yield response to fungicide applied at R1 (silking) growth stage.
Soil Type
Previous Crop
Tillage Type
Planting Date
Harvest Date
Potential Yield
Planting Rate
Camden Point, MO
Silt loam
Minimum tillage
200 bu/acre
34,000 seeds/acre

Site Notes:

Each seed product had two treatments:  1) No fungicide; 2) Stratego® YLD Fungicide applied at 5 fl oz/acre on July 17, 2017 at R1 (silking) growth stage.Disease incidence was as follows:  gray leaf spot - moderate; southern corn rust - low; crown rot - observed to be present.



Understanding the Results

Figure 1. Corn seed product response to fungicide application at R1 (silking) growth stage.
  • The application of Stratego® YLD Fungicide increased yield in five of the six brand blend products.
  • In previous Monsanto inoculated disease trials, under high disease pressure DKC60-88RIB, DKC62-53RIB, DKC63-21RIB, DKC64-35RIB, and DKC65-95RIB brand blend products rated moderate (4.5 to 5.5 on a scale of 1 to 9; with 1 being resistant and 9 being susceptible) to gray leaf spot (GLS).         
  • In this trial, the yield increase observed on five seed products with the application of Stratego® YLD Fungicide ranged from 7.1 to 27.1 bu/acre and is likely the result of the inhibition of GLS development.
  • In comparison, DKC65-81RIB brand blend, which rates as moderately resistant for GLS (4.0) saw no yield advantage from fungicide application. This seed product’s host resistance presumably provided adequate protection for the severity of GLS observed in Camden Point, Missouri during 2017; therefore, the application of Stratego® YLD Fungicide did not contribute to disease control for this seed product.
  • No significant differences in grain moisture content were observed across treatments.

What Does This Mean for Your Farm

  • Fungicides can protect yield when applied correctly.
  • The benefits of a fungicide treatment at the appropriate growth stage may have more impact when applied to moderate to susceptible (disease ratings) seed products under high disease pressure conditions.
  • Scouting plans should be in place prior to tasseling for fields with susceptible genetics, that are continuously corn-on-corn, or have a history of disease.
  • Yield potential, corn growth stage, disease risk, cost of fungicide, and corn commodity price should all be considered when deciding whether to spray a fungicide.
  • Farmers can further minimize the risk of disease-induced yield loss by selecting a resistant to moderately-resistant seed product when planting in disease-prone regions.
  • The data is a result of a single, non-replicated study conducted in Camden Point, Missouri and is intended to represent the seed products’ response under 2017 conditions for this region. Results may vary depending on disease presence, environmental conditions, and other factors.