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Know Your Sprayer Nozzles
Hope springs eternal – each spring. That’s especially true for farmers before they plant a seed in the ground. It’s the time of year when each field can yield 500-bushel-per-acre corn and 150-bushel-per-acre soybeans.
On paper, that is.
In reality, the moment it goes in the ground, your seed faces stressors such as compaction, cold, mud, powder-dry dirt, and bugs.
Then there are the weeds, including waves of waterhemp, Palmer amaranth, giant ragweed, and others touting resistance to multiple herbicide sites of action.
To preserve yield potential, correct pesticide application is a must. Not only that, it helps you place the correct amount of chemical on your crops and away from neighboring crops or farmsteads.
Fortunately, today’s sprayers enable you to precisely apply the right amount of chemical to every square inch of your fields. Just don’t neglect one component of what initially may seem to rank on the bottom of today’s technology: spray nozzles.
“A bad nozzle can make a bad day in a hurry,” says Dave Hillger, Dow AgroSciences Enlist field specialist.
look at the label
Nozzle selection is getting more play these days, particularly with the debut of new technologies like dicamba- and 2,4-D-tolerant herbicide systems. (Federal regulators have approvedMonsanto’s Roundup Ready 2 Xtend dicamba-tolerant soybeans. Dow’s Enlist 2,4-D-based technology is currently waiting on foreign approval of the herbicide-tolerant trait.)
Chemistries for these systems will list specific nozzles on their labels. Failure to follow guidelines will be illegal and could expose applicators to liability concerns.
“Right now, it is rare for specific nozzle requirements to appear on pesticide labels,” says Hillger. “My understanding is that this is the tip of the iceberg of what will come.”
Nozzles differ according to the droplet size they produce. Some nozzles that produce a smaller droplet are good for contact herbicides like Flexstar and glufosinate. Small drops enable chemicals to coat plants for optimal efficacy.
Other nozzles produce larger droplets. These work well for systemic herbicides that move throughout the plant. With these herbicides, it’s important to have large droplets hit the leaf surface so they can be readily absorbed.
Another perk is that large droplets are less prone to move off target. That’s particularly important to postemergence herbicide applications that could damage nontarget plants if they veer off target, says Hillger.
Nozzle manufacturers produce a nozzle chart that can help you pick the right nozzle for the right situation. “There are spray apps you can use to help you make the decision,” reminds Hillger.
One important reminder: These calculations are based on water, not chemical.
“There may be some difference when adding active ingredients and adjuvants,” he says. “It can slightly change the consistency of that droplet. More work is being done to characterize sprayer nozzles with the adjuvant or active ingredient.”
Know Output Volume
That’s because it can impact the nozzle output of chemical.
“If you were applying just 5 to 7 gallons per acre, output through the nozzle would be much different than putting out 15 to 20 gallons per acre,” explains Hillger. “With a higher output, you need a bigger hole to get the liquid out of the sprayer. It’s simple physics.”
Rate controllers actually do this when they increase pressure to compensate for higher speeds. Still, starting with the right nozzle in the first place helps alleviate this need to increase pressure to maintain desired output.
“While we understand getting across a number of acres is important, we certainly want to make sure the application is done correctly and not pushing the nozzle beyond capacity,” says Hillger. “At a higher speed, you have to have the selected nozzle produce the output and spray quality you need.”