North Central Ohio, across the Corn belt ! | Foliar Fungicide Use in Corn
by Pierce Paul, Dennis Mills
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Over the past few years there have been lots of discussions about the plant-health benefit of fungicide application in corn, and this year is no different. Research at OSU shows that the use of resistant hybrids is still the most effective, economical, and widely recommended control measure for foliar diseases (such as gray leaf spot and northern corn leaf blight) of corn. When a susceptible hybrid is planted under conditions known to favor the development of these diseases, an early application of a fungicide may be warranted. Both the gray leaf spot and northern corn leaf blight fungi survive in corn residue left on the soil surface from the previous growing season. If a susceptible hybrid is planted in a reduced-tillage, continuous corn field and conditions are favorable for disease development (extended periods of high relative humidity and moderate to high temperatures), extensive blighting of leaves may occur prior to grain fill, leading to substantial yield reduction.
To achieve the desired effect, fungicides should be applied at the proper time. The goal of fungicide application is to prevent disease from spreading to the ear leaf and the leaves above the ear, since these leaves contribute a significant portion (about 75%) of the carbohydrates for grain fill. If disease is present on the leaves below the ear leaf, applications should begin prior to tasseling. Fields should be scouted regularly to determine the appropriate time for fungicide application. A highly-susceptible hybrid combined with extremely favorable disease conditions may require two applications to reduce the level of disease; however, more than one fungicide application is generally not economical. Yield increase is often not enough to offset the cost of two applications. In addition, fungicide trials from 2006 showed that there was no economic yield benefit to applying fungicide in the absence of foliar disease.
The following should be taken into consideration when making decisions regarding fungicide application:
1- Susceptibility and yield potential of the hybrid
2- The amount of disease in the field
3- The growth stage of the crop
4- Weather conditions
5- Fungicide and application cost
6- Grain price
7- Directions and restrictions on product label
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C.O.R.N. is a summary of crop observations, related information, and appropriate recommendations for Ohio Crop Producers and Industry. C.O.R.N. is produced by the Ohio State University Extension Agronomy Team, State Specialists at The Ohio State University and Ohio Agricultural Research and Development Center. C.O.R.N. Questions are directed to State Specialists, Extension Associates, and Agents associated with Ohio State University Extension and the Ohio Agricultural Research and Development Center at The Ohio State University.
Information presented above and where trade names are used, they are supplied with the understanding that no discrimination is intended and no endorsement by Ohio State University Extension is implied. Although every attempt is made to produce information that is complete, timely, and accurate, the pesticide user bears responsibility of consulting the pesticide label and adhering to those directions.
All educational programs conducted by Ohio State University Extension are available to clientele on a nondiscriminatory basis without regard to race, color, creed, religion, sexual orientation, national origin, gender, age, disability or Vietnam-era veteran status.
Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, Keith L. Smith, Director, Ohio State University Extension.
TDD # 1 (800) 589-8292 (Ohio only) or (614) 292-1868 |
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