Prefar is one of the old standard herbicides that have been used on lettuce for more than 55 years. It is rare anymore to find an emulsifiable concentrate that is applied at 4 to 6 qt. per acre. A Yuma CO., AZ. grower/PCA survey conducted by the U of A last year indicated that 58% of the planted lettuce acres in Yuma were treated with Prefar. A USDA survey for the same time period indicated that 11% of the lettuce acres in AZ and CA were treated with Prefar. This may demonstrate the value of a strong local research and marketing effort as the manufactures home office, the Gowan Company located in Yuma and Dune Company (a division), has strong local ties. Gowan acquired Prefar from ICI in 1992 about the time that sprinkler irrigation of lettuce in Yuma was starting to replace furrow irrigation for stand establishment. Prefar works much better when incorporated with sprinklers. It also works best in coarse textured soils such as found in te Coachella Valley, CA. Prefar can produce between 0 and 100% weed control depending on the weeds present. It is good on annual grasses, Pigweed, Purslane and fair on goosefoot and lambsquarters. It is inconsistent on most other local weeds.

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

For questions or comments on any of the topics please contact Marco Pena at the Yuma Agricultural Center.
College of Agriculture, The University of Arizona, Tucson, AZ.