COLUMBIA, Mo. – There is a simple, inexpensive way to reduce errors in herbicide applications and limit off-target chemical drift, says a University of Missouri Extension weed management specialist.

Kevin Bradley supports the “Flag the Technology” program by the University of Arkansas Cooperative Extension Service.

The idea is simple: Color-coded bicycle flags or similar markers placed at field entrances or other conspicuous locations indicate the use of different herbicide technologies.

The system, which is gaining popularity in the Midwest, can make the difference between a healthy crop and a damaged or dead one, Bradley said.

Missouri agricultural retailers who make custom applications to many areas are beginning to use the system.

“When they pull into a field to make a herbicide application, the flags help to assure them that they have the right chemical in their tank to match the traits in that field,” Bradley said. “Also, they might be able to look at fields across the road, and if there are different colored flags in nearby fields, then applicators may think twice before spraying in windy conditions.”

Red flags signify conventional crop varieties with no herbicide technology traits while white may represent Roundup Ready technology that is tolerant to glyphosate. Bright green indicates LibertyLink technology, which is tolerant to glufosinate. Bright yellow is the color for Clearfield technology, which is tolerant to imazethapyr (Newpath) and imazamox (Beyond). Multiple flags represent stacked technologies.

Preferred flags are 12-by-18-inch triangles (a little larger than the typical bicycle or ATV safety flag) mounted on 6-foot fiberglass poles.

Bradley said the flag method will likely gain significance in two to three years, when crops with new herbicide-resistance traits enter the marketplace. Farmers and agricultural retailers who make herbicide applications to large acreages, deal with multiple employees and apply multiple products will find the program of great value, he said.

A brochure about the Flag the Technology program is available at A two-minute video overview from the University of Arkansas Division of Agriculture is available at

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