Disease: Gray Leaf Spot
Gray leaf spot (GLS) is considered the most economically damaging foliar corn disease in the United States. It overwinters on infected corn residue at the soil surface and is easily inoculated in fields with limited crop rotation practices.
Timing And Transition
As temperatures warm in the spring, viable spores are splashed by rain or transported by wind to new plant tissue. Infection generally occurs on young corn leaves and progresses upward in the plant at varied severities and speeds during prolonged periods of warm temperatures and high humidity.
Identification and Dissemination
Foliar symptoms of GLS start as small lesions surrounded by yellow halos but transition to elongated rectangular spots. These dark brown or gray rectangles arrange parallel to leaf veins, produce spores irrespective of the relative humidity and ultimately reduce the amount of photosynthetic leaf area needed for grain fill.
Management
There are a number of strategies to manage GLS in corn. Crop rotation, residue management and selection of tolerant hybrids are the most effective cultural tactics. However, many instances of substantial infestation warrant a fungicide application when disease first appears and may require sequential treatment. Typically, applications occurring at the V1-R1 growth stage provide the greatest disease efficiency and economic return.
Research has indicated that strobilurin (FRAC Group 11) and triazole (FRAC Group 3) fungicides are among the most effective in instances of heavy disease pressure, including an SDHI (FRAC Group 7) can greatly improve efficacy of foliar fungicide applications.
- Xyway® brand fungicides from FMC (FRAC Group 3) are the first and only foliar fungicide to be applied At-Plant. This strategy helps protect the plant’s yield potential from day one. This application means protecting all the leaves, including lower leaves, are protected, reducing the buildup of inoculum and disease pressure during vegetative stages, thus lowering the overall impact of foliar disease.
- Adastrio™ fungicide (FRAC Groups 3, 7 & 11) can be applied foliarly and has three active ingredients to help protect corn from gray leaf spot. This innovative fungicide combines a novel molecule in the SDHI class, fluindapyr with one of the most systemic triazoles on the market, flutriafol and azoxystrobin.
- Foliar fungicides like Lucento® fungicide (FRAC Groups 3 & 7) and Topguard® EQ fungicide (FRAC 3 & 11) can be applied in-season at the V1-R1 growth stages to help protect against this yield-robbing disease.
Performance Data
GRAY LEAF SPOT % SEVERITY
2018 TRIAL SITES: NE, KS, IL - 3, KS, TN, PA
FOLIAR FUNGICIDE APPLICATION IMPACT ON DISEASE SEVERITY AND YIELDS
UNIVERSITY OF NEBRASKA - 2017
FMC Product Solutions
Always read and follow all label directions, precautions and restrictions for use. FMC, the FMC logo, Adastrio, LFR, Lucento, Topguard and Xyway are trademarks of FMC Corporation or an affiliate. ©2023 FMC Corporation. All rights reserved. 22-FMC-3111 07/23