Dicamba residue persistence in processing tomato

Abstract There is zero tolerance for dicamba and dicamba metabolite residue in tomato (Solanum lycopersicum L.) fruit following exposure to dicamba. Field trials were conducted in 2020 and 2021 to determine the persistence of dicamba and metabolite (5-hydroxy dicamba and 3,6-dichlor-osalicylic acid [DCSA]) residue in processing tomato shoots and fruits. Dicamba was applied 49 d after transplanting at 0, 0.53, 5.3, and 53 g ae ha–1. Tomato plants were harvested 5, 10, 20, 40, and 61 d after treatment (DAT). No 5-hydroxy dicamba was recovered from any sample. In 2020, the DCSA metabolite was detected from tomato shoot tissue when dicamba was applied at the 53 g ha–1 rate at 0 (14 µg kg–1), 5 (3 µg kg–1), and 20 DAT (5 µg kg–1) and from tomato fruit tissue at 53 g ha–1 at 20 (2 µg kg–1) and 61 DAT (2 µg kg–1). In 2021, DCSA was not detected from tomato shoot or fruit tissues at any harvest date. By 5 DAT, dicamba was only detected from tomato shoot tissues treated with 53 g ha–1. At 0 DAT, dicamba residue was detectable only from tomato fruit on plants treated with 53 g ha–1. Tomato fruit dicamba residue from plants treated with 5.3 g ha–1 had a predicted peak of 19 µg kg–1 at 11.3 DAT. Tomato fruit dicamba residue from plants treated with 53 g ha–1 decreased from 164 to 8 µg kg–1 from 5 to 61 DAT. Furthermore, this study confirms that dicamba is detectable from tomato fruits at 61 DAT following exposure to 5.3 or 53 g ha–1 dicamba. Growers who suspect dicamba exposure should include tomato fruit tissue with their collected sample or sample tomato fruits separately.