Canola School: Matching nozzles to spray needs

Getting the right spray quality and the right water volume can be a bit tricky, and when it comes to nozzles, there are a few factors to consider when picking the right one.

When it comes to nozzle size and spray pattern, there are two important questions our expert for this Canola School episode asks: what’s the active ingredient and what’s the target?

“Those are the two main things that determine the right spray quality to use,” says Tom Wolf of Agrimetrix and Sprayers 101.

Wolf says that most of the time the default is a coarse spray quality — the average spray quality that most modern air induction and other low-drift tips produce — which could be tweaked, according to what the crop is, and what’s in the tank.

“As we have increasingly complex tank mixes, for maybe resistance management, that becomes a little more critical,” says Wolf.

Wolf says that most of his customers will have three nozzles, selected by water volume: a 5 gallon tip for burn-off, a 10 gallon tip for in-crop, and maybe a 15 or so gallon tip for late-season spraying like fungicide or desiccant applications. A low-drift version of each of these is also an option, for when conditions warrant, because as Wolf adds, “agronomy is all about timing, and a sprayer is an agronomic tool. You want to make sure you can do it at the right time.” (Story continues below video)

As for water volume factoring into the equation, it allows some leeway for spray quality.

“Water kind of gives you permission to spray the coarser sprays. The lower the water volume is, then the finer the spray is that you can actually get away with,” says Wolf. “As it gets windier, and we use coarser and coarser nozzles, we should always increase the water volume so our droplet density doesn’t suffer too much.”

Wolf recognizes that increasing water volume is a bit of a productivity issue, but it’s also an opportunity to spray when it’s a bit breezy, and still get the job done at the right time.

After the right nozzle has been selected, the next thing to do is to look at the tank mix, the modes of action in the tank mix, and the weeds in the field, says Wolf. If you’re after grassy weeds, a slightly finer spray is required to hit that plant structure and get the spray to stick. For broadleaf weeds, the leaves are relatively larger, where larger drops will stick a bit better.

If the tank mix includes herbicides for both grassy and broadleaf weeds, always consider the most limiting factor, says Wolf, and opt for a spray quality that will control the grassy weeds.

“If you needed to spray in the wind, you can move that a little coarser, just by adding more water,” says Wolf. For example, if you normally go with seven to ten gallons and you need a coarser droplet size, bump that water volume up to say ten to 12 gallons.

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