2019 ASHS Annual Conference

Horseradish is an important specialty crop produced in southwestern Illinois, accounting for approximately half of US production. Since this crop is grown in rotation with agronomic row crops in Illinois, it is susceptible to herbicide injury caused from the movement of dicamba herbicide (3,6-dichloro-2-methoxybenzoic acid) applied in dicamba-tolerant soybeans that are grown nearby. Dicamba is a broad-leaf herbicide, which may injure crops or natural vegetation in close proximity. Therefore, studies were conducted to simulate dicamba drift events to determine resulting horseradish crop injury and root yields, and herbicide residue levels in roots, as well as to determine variety response to ½ and 1x rates of this herbicide. Simulated drift rates of dicamba were shown to not cause horseradish injury or yield reduction, and no dicamba residues were detected in roots. However, horseradish varieties differed in their overall visual injury to the higher ½ and 1x rates of dicamba, ranging from 54 to 81%, and 71 to 92% injury respectively, at 28 days after treatment, with ‘604’ being the least sensitive variety of those evaluated. Horseradish height reduction and foliar necrosis at 28 DAT was also lowest for ‘604’ horseradish compared to other varieties. Dry root weight reduction ranged from 7 to 65% and 54 to 81%, respectively for horseradish varieties at ½ and 1x rates of dicamba. This research indicates that horseradish will tolerate dicamba drift events, resulting in no yield loss, but higher application rates will definitely affect yield, with injury differing among horseradish varieties.