Choosing the right product to spray is important, but so is controlling how it’s applied, says a well-known researcher.
“The challenge is primarily to control the pests, but we also have to control where the spray goes,” said Dr. Tom Wolf, a former scientist with Agriculture Canada, and now working with AppliTech Canada conducting research and training for retailers.
“Everyone is watching agriculture in terms of our environmental footprint, and we have to make sure our spray goes where it is intended to go,” Wolf told the first Cereal Disease conference here recently.
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For example, some fungicides can be harmful to aquatic organisms and vertebrates.
Producers need to know what part of the plant is infected and where the fungicide needs to hit to beat the disease. Diseases that live higher up in the canopy, like fusarium head blight, don’t require sprays with high water volume, Wolf said. “If you are going farther down into the canopy and hitting the flag leaf or the penultimate leaves, you need more water to get there,” Wolf said.
Wolf said coarse spray is best for fungicide. “You look for a nozzle and an operative pressure that produces a coarse spray, whether you are doing fungicide or herbicide work. Insecticide is a little different, and that depends on what you’re trying to hit. We’ve seen such tremendous success with coarse sprays in fungicide and we see no reason to go any finer than that.”
Wolf has worked with researchers from North Dakota State University to determine the best way to spray fusarium head blight. This disease requires targeting of the wheat head, a timely application and uniform distribution.
While Wolf doesn’t normally recommend double nozzles, he said spraying for fusarium head blight is the exception. Single nozzles being used for fusarium should be positioned forward to hit the heads.
Herbicides
In a pre-seed burn-off, three to five gallons per acre is adequate for most herbicide application, Wolf said. Sometimes water volume can depend on mode of action.
“The days of spraying glyphosate by itself in an era of glyphosate-resistant weeds are probably coming to an end or are over already. The days of spraying with its tank-mixed partner at the same rate as you are spraying glyphosate alone are probably also over because you have to consider the mode of action of the tank-mixed partner,” said Wolf.
Larger canopies require more water, he said. If the wheat head is the target, seven to 10 gallons is an appropriate amount. More water is needed to hit the flag leaf or the penultimate leaves in the lower canopy.
“The farther down you have to go, the more water you will need to get there. It’s just simple math. You’re losing spray volume as you go down into that canopy,” he said.
Wolf advocates using low-drift nozzles to reduce spray drift without reducing coverage. In order to make these nozzles more effective, producers can add more water.
“You don’t have to double or triple your water volume. You can go from 10 to 12 or from seven to 10. You have to make that 20 to 30 per cent increase in water volume. That brings your small-drop component right back up to what it was,” said Wolf.
