Cured leaf residues following applications of fluopicolide, indoxacarb, and oxathiapiprolin to flue-cured tobacco
Pesticide residues found on cured tobacco remain a large concern to the allied tobacco industry. To better quantify cured leaf residues, three active ingredients (fluopicolide, indoxacarb, and oxathiapiprolin) were applied to flue-cured tobacco grown in six North Carolina environments from 2016 to 2018. Fluopicolide residues were consistently among the highest documented in this evaluation (7.25 mg/kg maximum), which was most likely a result of the compound having the shortest PHI (7 days) among the products tested. The highest indoxacarb residue was 2.15 mg/kg, which was identified in lower-stalk position samples collected from one environment in 2018. Additional data suggests that indoxacarb residues are likely to be < 2.0 mg/kg. Oxathiapiprolin was below the limit of quantification (0.09 mg kg-1) in 98.6 % of the samples analyzed and averaged 0.10 mg/kg in the lower-stalk position of one environment in 2017. Results from this study indicate that cured leaf residues from fluopicolide are moderate relative to indoxacarb and oxathiapiprolin, but are not as great as other pesticides for which Guidance Residue Limits are currently established. Furthermore, it is plausible that residues from commercial farming operations would be lower than those reported due to Integrated Pest Management practices. Further investigations are warranted in order to better identify residues resulting from applications delivered using recommendations put forth by Cooperative Extension Services in the southern U.S.