Herbicides for Control of Volunteer Horseradish (Armoracia rusticana) and Potential Carryover to Subsequent Horseradish Production

Volunteer horseradish plants that emerged from root segments remaining after harvest can reduce yields of rotational crops as well as provide a host for pathogens and insects, thus reducing the benefits of crop rotation. POST applications of halosulfuron in corn can be an effective component to improve management of volunteer horseradish, but the replant interval from application to safe planting of commercial horseradish has not been determined. Fall herbicide applications are another possible volunteer horseradish management strategy than can be implemented once crops are harvested. Therefore, field experiments were conducted to evaluate the safe replant interval of horseradish following halosulfuron applications and to determine the efficacy of fall herbicide applications for volunteer horseradish control. Visual estimates of horseradish injury were greatest (85%) in plantings made zero months after halosulfuron applied at two times the approved rate; moreover, for all rates, injury decreased as the time after halosulfuron application increased. No herbicide injury or root biomass reduction occurred on horseradish at any halosulfuron rate from replanting beyond 4 mo after halosulfuron application. Control of volunteer horseradish was 91% or greater for all fall herbicide applications that included 2,4-D. Furthermore, volunteer horseradish shoot density was the lowest following combinations of 2,4-D tank-mixed with halosulfuron or rimsulfuron : thifensulfuron (0.2 and 0.4 shoots m⁻², respectively) compared with the nontreated control (5.1 shoots m⁻²). This research demonstrates the effectiveness of both halosulfuron and 2,4-D as components of an integrated management strategy for volunteer horseradish control and the potential for halosulfuron applications without soil persistence beyond 4 mo affecting subsequent commercial horseradish production.Nomenclature: 2,4-D; halosulfuron; rimsulfuron; thifensulfuron; corn, Zea mays L.; horseradish, Armoracia rusticana P.G. Gaertn., B. Mey. & Scherb.