Comparison of Dicamba and 2,4-D Injury to Field-grown Tomatoes1

A 2-year study of tomato injury caused by broadcast sprays of 2,4-dichloro-phenoxyacetic acid (2,4-D) and 2-methoxy-3,-6-dichlorobenzoic acid (dicamba) indicates the 2 herbicides caused very similar injury symptoms to both plants and fruits of field-grown tomatoes. Yields were reduced by 2,4-D and dicamba when the herbicides were applied to the plants in June, but no significant yield reductions were observed from mid-August applications except for dicamba at 0.2 kg/ha in 1971. Although yields were not reduced in the late season applications, a majority of the fruit was unmarketable because of interior defects. Dicamba was found in leaf tissue for at least 6 days after application, but no detectable amounts of 5-hydroxy-dicamba were observed in this time period.