Saturday, June 13, 2015

Too Early For Spraying Fungicide on Corn?

Positive results, in terms of disease control and yield for foliar fungicide applications made before tassel, at tassel, and even as late as R3, are not rare.  From year to year, the most consistent results and the greatest benefits are seen when applications are made at tasseling. Some diseases like Southern rust and northern corn leaf blight may show up first on the upper leaves, but in most years this usually occurs too late, sometime after R3, to significantly affect grain yield.  At brown silk, being R2, the number of rows of kernel per ear and the number of kernels per row are already made.  Therefore, applying a fungicide at or after R2 will not change these numbers, even if disease lesions develop on the upper leaves.  However, severe blighting of the upper leaves after R2 may affect the size of the kernels, and as such, we may see a benefit from applying a fungicide between R2 and R3.

                Before making a decision to apply a fungicide, walk the field and look for disease lesions and determine the growth stage of your crop.  If your crop is at R1 or early R2, and you have a susceptible hybrid, and there are disease lesions on the leaves near the ear, you may see a benefit from a fungicide application.  However, if your hybrid is resistant or moderately resistant, and your crop is past brown silk, being R2, and lesions are restricted to the leaves below the ear, you are less likely to see a benefit from applying a fungicide.  In addition to not always being as effective as VT/R1 applications, late application may be off label.  Some fungicides cannot be applied after R3 or R4.  Before making an application decisions, please read product labels carefully.  

We continue to brainstorm new ways to offer additional features within MyFarms such as pest and disease alerts. Burrus is pleased to offer the addition of the “Gray Leaf Spot Alert System” within the MyFarms system to their customers. This new feature will only be available to those who have transferred their uploaded fields to planting records within MyFarms. This can be done by clicking on the “Data tab”, which is located on the top of the MyFarms screen.  Once you click on the “Data tab”, the year, field, and operation tabs will appear on the left hand side of the screen within MyFarms. Be sure to select the correct year and field that you wish to monitor for gray leaf spot.  Lastly, choose “planting” within the operation tab, click on “add an operation”, and then choose “record”.  Within the “record”, you will input your planting data for this particular field, and click save. 

-Courtney Brown; Missouri Intern

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