ALDICARB ON GREENHOUSE CHRYSANTHEMUMS IN ONTARIO: EFFICACY FOR CONTROL OF LIRIOMYZA TRIFOLII (BURGESS) (DIPTERA: AGROMYZIDAE) AND RESIDUES IN FOLIAGE

In two field tests, larvae of Liriomyza trifolii (Burgess) were not controlled by aldicarb (Temik 10G) at three times the recommended rate when applied to soil, dry foliage, or wet foliage of chrysanthemums (cv. White Marble) in Ontario. A second treatment of aldicarb 3 weeks after the first did not prevent the increase in leafmining. Assessment of the top 10 leaves at harvest showed no significant differences in numbers of mines greater than 2 cm between check and treated plots. Residues of aldicarb and its degradation compounds, aldicarb sulfoxide and aldicarb sulfone, were detected by capillary gas chromatography with thermionic specific detection. Substantial residues (> 100 μg/g as total residues), particularly of aldicarb sulfoxide, were found within the 1st week after treatment, but dissipated rapidly in upper leaves by day 7 after the first aldicarb application. Lower leaves, however, maintained residue levels at a constant level for a 3-week period following the first and second applications. Residue levels on lower leaves were consistently higher after wet-foliage application of aldicarb than after soil application.