SIMAZINE (PRINCEP), a persistent pre-emergence herbicide, has given broad-spectrum weed control in orchard crops. Generally it has been used by orchardists with excellent results. As it depends on water to activate it and move it into the soil, simazine's effectiveness is dependent on soil environment and the cultural practices employed.

This work was supported, in part, by the Geigy Chemical Company. Soils in these trials were analyzed by Jim Quick, AES Soils Lab-UCD and John Rible, AES Diagnostic Lab-UCR. Farm advisors cooperating in these trials included: Roy Jeter, Glenn County; Dave Chuney, Sutter County; John Smith, Placer County; Clem Meith and Floyd Perry, Butte County; Dave Holmberg, York County; Tom Aldrich, Colusa County; Jim DeTar, Solano County: Irving Grover, Napa County; Kim Roberts, Sonoma County; Chet Hemstreet, Lake County; Ed Stilwell, formerly Contra Costa County now UCR; Gordon Morehead, Sacramento County; Don Rough and Fred Charles, San Joaquin County; Verner Carlson and Lonnie Hendricks, Merced County; Bill Collins and Ron Tyler, San Benito County; Bill Seyman, Santa Clara County; Bill Barnett, Sutter County; Harry Agamalian, Monterey County; Ed Koch, Santa Cruz County; John Foott, and Will Cawelti, San Luis Obispo County; Todd Browne and Marvin Gerdts, Fresno County; Jim LaRue, Vince Schweers, and Steve Sibbitt, Tulare Co.; Lyndon Brown, Kings Co.; Harold Kempen, Kern Co.; Dick Puffer, Los Angeles Co.; Bob Rackham, San Bernardino Co.; and Dean Halsey, Riverside Co.