Effects of weathering and flue-curing on monocrotophos residues on tobacco.

Disappearance of monocrotophos from flue-cured tobacco was studied at three locations (Kinston, Clayton, and Reidsville, North Carolina) in 1973. Average residues on green tobacco leaves collected immediately after application were 41 and 84 ppm, respectively, for application rates of 0.56 and 1.12 kg/ha. Levels declined to about 18 and 40 ppm for the two rates three days after application, to about 9 and 23 ppm at five days, and to about three and eight ppm at nine days. Conventional curing reduced residues on flue-cured tobacco by at least 99%.