115-1 CONTINUOUS USE OF ALTERNATIVE FUMIGANTS FOR THREE YEARS IN STRAWBERRIES Steven Fennimore 1 , Shachar Shem-Tov 1 , Husein Ajwa 1 , Frank. N. Martin 2 , J. Ben Weber 1 , John Rachuy 1 , Jayesh Samtani* 1 1 University of California, Davis, Salinas, CA 93905. 2 USDA ARS PWA, Salinas, CA 93905 Summary. Field studies were conducted at the Spence USDA-ARS research farm in Salinas, CA and at a commercial field near Oxnard, CA during the 2005-06, 2006-07, and 2007-08 seasons. The objective of this research was to evaluate three years of continuous use of Telone II/InLine/ Telone C35 (formulations of 1,3-dichloropropene + chloropicrin) and Midas (50% iodomethane + 50% chloropicrin, included at Salinas only) for strawberry fruit production and weed control compared to MB Pic (67% methyl bromide + 33% chloropicrin). At both locations continuous use of InLine/ Telone C35 or Midas performed similarly to MB Pic in all three years. Repeated use of InLine/Telone or Midas did not result in reduced efficacy after continuous use. Introduction. In some California strawberry fields methyl bromide (MB) has been applied annually for a decade or more without loss of performance. However, the phase out of MB is now resulting in continuous use of alternative fumigants on the same fields. It is not known whether there will be loss in performance where alternative fumigants are used continuously. The objective of this work was to compare the continuous use performance of MBPic and InLine/Telone or Midas on strawberry yield and weed control at Salinas and at Oxnard, CA. Materials and Methods. At both sites fumigants were applied by commercial broadcast shank application in the 2005-06 and 2007-08 seasons, and by drip chemigation in the 2006-07 season (Table 1). Salinas. The study was initiated on Aug. 17, 2005 when broadcast shank applications of MB Pic at 350 lbs/A, Telone II (97.5% 1,3-dichloropropene, 1,3- D) at 15 GPA co-injected with chloropicrin (Pic) at 200 lbs/A, and Midas (50% iodomethane, IM; 50% Pic) at 300 lbs/A were made (Table 1). Plots were 33 ft wide by 280 ft long, and individual beds were 52 inches wide. ‘Diamante’ (2005- 06) or ‘Albion’ (2006-07 and 2007-08) strawberry were planted at a spacing of 10 inches between rows and 15 inches between plants within rows. Weed densities were measured in two 50 ft sample areas per plot and converted to weed densities per acre. Weed densities were recorded on Jan. 31 and Apr. 20, 2006, Feb. 20, Mar. 22 and May 22, 2007, Feb. 7, Feb. 15, Apr. 28 and July 8, 2008. Fruit yields for all trials were recorded from two sample areas per plot of 40 plants each. Fruit