Herbicide injury to wheat following a lettuce crop

By Barry Tickes, UA Area Agriculture Agent

It is common to plant wheat following lettuce in Yuma County and California’s Imperial Valley.

The three soil active herbicides used on lettuce, Bensulide (Prefar), Benefin (Balan), and Pronamide (Kerb) can cause temporary injury to wheat. Although some temporary injury is not unusual, it rarely causes losses in yield or quality and is normally not considered a problem.

Pronamide moves readily with irrigation water and it is normally gone by the time the wheat is planted. The Kerb label specifies a rotational interval of 12 months. A good irrigation will help move this herbicide out of the root zone and 12 months is not usually needed.

Bensulide and Benefin stick to medium and fine textured soils. Irrigation water is ineffective in moving it below the root zone. The rotational interval for these is shorter than for Kerb. It takes four months for Bensulide and 10 months for Benefin.

Tillage is the best way to minimize potential crop injury from Bensulide and Benefin.

Contact Tickes: (928) 580-9902 or btickes@ag.arizona.edu