INSECTICIDE RESIDUES ON PINE BARK: INFLUENCE OF TREES, SAMPLE VOLUME AND SIZE ON VARIABILITY1

Abstract

Residues of carbaryl (Sevimol®) in ponderosa pine bark were quantified by gas chromatography and the major sources of experimental error were determined. Quantification of carbaryl residues was significantly affected by between-tree variation and disc size (bark volume). Variation between trees had the greatest effect on residue estimates. Mean carbaryl residues for all trees ranged from 241 μg/g of bark to 1418 μg/g of bark. Nonsignificant tree-disc size interactions indicated that residue levels were fairly consistent within trees. Prediction curves were constructed to project levels of precision for combinations of discs and trees.