Pest control with drip‐applied dimethyl disulfide and chloropicrin in plastic‐mulched tomato (Solanum lycopersicum L.)

Dimethyl disulfide (DMDS) is used as a preplant soil fumigant for weed and soilborne pathogen control in plasticulture vegetable crops. The objective of this research was to determine the control efficacy of emulsifiable concentrate (EC) formulation of DMDS or DMDS + chloropicrin (Pic) on weed and Fusarium wilt in tomato (Solanum lycopersicum L.) plasticulture.The effective DMDS rates required to provide 50% (ER50 ) control of purple nutsedge (Cyperus rotundus L.) were 210 and 340 kg ha-1 at 4 weeks after fumigation (WAF) in fall 2017 and fall 2018, respectively, while these values increased to 348 and >467 kg ha-1 , respectively, at 12 WAF. The ER50 values of DMDS + Pic were 150 and 240 kg ha-1 at 4 WAF in fall 2017 and fall 2018, respectively, while these values increased to 255 and 450 kg ha-1 , respectively, at 12 WAF. DMDS + Pic was generally more effective than DMDS for C. rotundus control. The high rates of DMDS or DMDS + Pic provided adequate C. rotundus control in early season but failed to provide effective control by season end. In addition, DMDS + Pic injections through drip tape effectively reduced Fusarium oxysporum f. sp. lycopersici (FOL) inoculum while DMDS alone was generally ineffective.Injection of the EC formulation of DMDS or DMDS + Pic through drip tape should have been provided a viable option for C. rotundus and Fusarium wilt control in plastic-mulched tomato. However, supplemental weed management actions, such as herbicide applications, may be required to achieve season-long control. © 2019 Society of Chemical Industry.