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Make fungicides pay on soybeans

soybean field
CONSIDER ALL FACTORS: If you’re going to spray fungicides, time it right, specialists say. You will need to look beneath the canopy to judge stage of development.
Soybean Corner: Increase your odds of getting a payback for applying fungicides.

I saw enough data this winter to convince me to spray fungicides on soybeans. We have never done it before. Can I do it with my own self-propelled sprayer, or should I hire it done? What do I need to know to make this application pay off?

The panel of Indiana certified crop advisers answering this question includes Don Burgess, agronomist with A&L Great Lakes Labs, Fort Wayne; Jesse Grogan, agronomist with Ag Reliant Genetics, Lafayette; and Bryan Overstreet, Purdue University Extension ag educator in Jasper County.

Burgess: Prior to deciding on whether to make your own application of a fungicide, it’s critical to thoroughly read the label. Doing so will not only detail the proper use of the pesticide, but may also reveal if any additional costs might be needed prior to making the application. This could include required nozzles or other components. Other operational costs such as fuel, equipment depreciation and labor need to be considered.

It’s also important to factor in the differences in the amount of yield loss associated with making the application, based on the size of your sprayer vs. the custom applicator’s sprayer. A wider boom will cause less yield loss due to wheel tracks than a smaller boom. This difference alone may offset cost of the application. Data from Purdue University indicates an average yield loss of 2.5% from wheel tracks on a sprayer with a 60-foot boom, while a sprayer with a 120-foot boom caused an average yield loss of 1.3%. This is a difference of about 0.72 bushel at 60 bushels per acre. With $10 soybeans, this is a $7.20 difference, which may cover the cost of the application.

Grogan: Soybean fungicides are effectively applied with self-propelled sprayers. Use drive lines from previous trips across the field to apply postemergence herbicides in June. One can spray in these passes without running over too many plants if you have autosteer. Soybean fungicides are applied in late July to early August at the R3 growth stage, which is three nodes with quarter-inch pods on top of plants. Crop coverage is important. One must apply 15 to 20 gallons per acre and at higher pressure. A one-time application of fungicide is most cost-effective. Some varieties are more responsive to fungicide than others. Your seed representative may have information to help with that.

It is useful to scout fields for foliar diseases like frogeye leaf spot. Remember that most foliar fungicides are not effective for diseases like downy mildew or sudden death syndrome. Review fungicide efficacy charts for target diseases to control. Custom applicators do a great job and can cover more acres in less time, and have experience with soybean fungicides.

Overstreet: You can apply it, but here are some stipulations you may want to think about. If the product is a restricted-use pesticide, do you have an applicator’s license? You may also look at the number of tracks you are going to make across the field. Does the custom applicator have wider equipment? If it is flown on, you will not have any tracks.

As far as payback, decide on what diseases you’re focusing control on to make sure that you have the proper fungicide to use. Look at that fungicide’s label for the proper timing of the application. When looking at the label, also look at harvest restrictions. Some of the fungicides can’t be sprayed once the soybean plant gets to the R5 stage.



TAGS: Fungicide
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