CORESTA Congress, Online, 2022, Agronomy/Phytopathology Groups, AP 36

Agrochemical residues: recent experiences with cyantraniliprole, flutriafol, flutriafol + azoxystrobin, and S-metolachlor

VANN M.C.; CHEEK J.A.; MACHACEK J.L.; WHITLEY D.S.
Department of Crop & Soil Sciences, North Carolina State University, Raleigh, NC, U.S.A.

Recent pesticide residue investigations for cyantraniliprole, flutriafol, flutriafol + azoxystrobin, and S-metolachlor applications were conducted in flue-cured tobacco. Field trials were conducted in five North Carolina growing environments from 2019 to 2021. Across all growing environments, cyantraniliprole residues were less than 2.0 ppm but were highest in the uppermost stalk position. The highest mean residue within a single growing environment was 5.21 mg kg-1, which is nearly 3.5 times lower than the CORESTA Guidance Residue Level (GRL) for cyantraniliprole (18 mg kg-1). Conversely, flutriafol residues ranged from 1.25 to 4.57 mg kg-1 and were highest in the lowermost stalk position. The highest flutriafol residue was recorded in 2019 in lower-stalk tobacco sampled at the Cunningham Research Station (9.30 mg kg-1). The same trends were documented in the combination treatment of flutriafol + azoxystrobin, although azoxystrobin residues were < 1.0 mg kg-1 across all field sites. Residues of S-metolachlor were not detected in any stalk position group. Ultimately, our research implies that repeated applications of cyantraniliprole and azoxystrobin + flutriafol should not result in cured leaf residues of cyantraniliprole or azoxystrobin that would be of concern to cigarette manufacturers. However, we realize that very little is known about flutriafol and how residues might be viewed by those same manufacturers. Given the dire need for additional tobacco fungicides with novel modes of action, flutriafol should be further evaluated for efficacy against foliar leaf spot disease.