Friendly Reminder About Herbicide Drift

Watch conditions, know what's in the tank, and the field.

Tom Bechman

Published: Jun 4, 2010

Testing the corn planter before you start is always a good thing, especially if you're doing a research plot and want a depth which requires settings not normally used on the planter. So when Indiana Prairie Farmer and Purdue University Extension Service of Tippecanoe County planted a replicated corn plot last week, they asked the Throckmorton Ag Center employee to run the planter far enough to check the depth to make sure they had one inch, two inch and about three-inch deep settings for their trial.

He chose to test it in the 50 foot-wide ally between replicated blocks of the treatments. "But you're going to plant soybeans in this alley, you said," commented Jeff Phillips, Tippecanoe County Extension ag agent. "And you said they're Roundy Ready. This corn is Liberty Link which is resistant to Ignite. But it's not resistant to glyphosate."

The long-time employee assured us that's why we didn't need to worry about planting Liberty-Link tolerant seed corn in the alleyway where he was going to later plant soybeans while testing. The glyphosate would take it out. "Yes, but what about our plot? We don't want that taken out," Phillips emphasized.

The employee was confident he could do it, because he's a trained applicator who knows not to spray when it's windy. Believe it or not, most experts say in Indiana 9 to 10 miles per hour is windy. Instead, pick a very calm time. He also will apply glyphosate with a small, 15 foot boom he built especially for spraying plots. That gives him better control and visibility of how the sprayer is performing, and whether or not drift is likely.

Staying away from windy days, even if you're behind in getting spray applied, is the number one factor to avoiding drift. The second is knowing what's in the field next to where you will apply the herbicide. In this case, as a classic example, Liberty Link corn is tolerant to Ignite, which is the same active ingredient once known as Liberty, but as susceptible to any corn to glyphosate. Likewise, Roundup Ready corn is tolerant to glyphosate, but deathly susceptible to Ignite. It applies both in drift situations and when someone forgets what's planted where, or what residues might be still hanging around in the in the spray tank because it wasn't cleaned properly.

It's also important to add the right adjuvant suggested on the label to the mix, specialists say. Some make sprays more effective, some make the spray hotter. And there are drift agents that may help retard drift. However, most specialists caution that adding a drift retardant isn't a license to spay Roundup Ready soybeans next to a Liberty Link test plot with glyphosate in 20 mile per hour winds!