Injury to Wheat from Herbicides Used in Lettuce (January 21, 2015)

Wheat is often grown following lettuce in this region the three most commonly used herbicides in lettuce all can cause injury to wheat. Bensulide (Prefar), Benefin (Balan) and Pronimide (Kerb), inhibit root growth in many grasses and can injure wheat if much of the herbicide has remained in the soil when it is planted.

Pronamide (Kerb), moves downward with sprinkler irrigation but not with furrow irrigation. Injury to wheat was more common prior to the widespread use of sprinklers in lettuce. Lettuce that was furrow irrigated from start to finish is at greater risk from Kerb than are fields that were germinated with sprinklers. Tillage and a good flood irrigation prior to planting wheat can reduce potential injury.

Bensulide (Prefar), is safer to large seeded grasses than it is to wheat but injury can occur in rare instances. It adheres more strongly to medium and fine textures soils than pronamide and it is difficult to move with water. Tillage is the best way to reduce injury potential to wheat.

Benefin (Balan), possess the greatest risk to wheat following lettuce. It also sticks strongly to medium and fine textured soil and is difficult to move. It is a dinitroanaline (yellow) herbicide like Treflan and Prowl. These herbicides can be used safely in wheat if applied after the wheat is well established or planted well below the herbicide.

Wheat can tolerate a fair amount of injury and recover to produce normal yields.

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To contact Barry Tickes go to: btickes@ag.arizona.edu.