Comparative Persistence of Pesticides on Selected Cultivars of Specialty Vegetables

Abstract

The behavior and dissipation of several pesticides on selected cultivars of specialty vegetable crops were compared to determine appropriate preharvest intervals for compliance with maximum residue limits. To reduce application variability, a tank mix of pesticides was applied for each trial. Residues of eight pesticides applied to bok choi, Chinese broccoli, and fuzzy squash were similar for the two leafy vegetables; residues were higher than on squash because of the latter's larger mass-to-surface area ratio. Whereas residues of five of the nine pesticides applied to cabbage, Chinese cabbage, and bok choi did not differ significantly from 3 to 14 days after application, residues of cypermethrin and three fungicides were significantly higher on Chinese cabbage and bok choi. The residue deposits of the pesticides were about 50% lower on Chinese cabbage and 90% lower on cabbage than on bok choi. Dissipation of residues on different cultivars of lettuce and cabbage were compared after application of nine pesticides. With the exception of captan, residues on head lettuce were lower than on the other lettuces on day 1; cultivar differences were not significant for most of the nine applied pesticides on days 3 and 8. Generally, residues of the nine individual pesticides on storage cabbage, savoy cabbage, Chinese cabbage, and tah tsai did not differ significantly from day 1 to day 7 after application. Residue concentrations were generally significantly higher on bok choi than on the other cultivars. Residue deposits generally correlated with the rate of application; residues of captan, however, were about 50% of the predicted value. Significant differences in deposit and dissipation were observed among cultivars and pesticides, with dramatic initial decreases for diazinon and parathion. Because of their higher exposed surface area-to-mass ratios, leafier crops had higher residue concentrations than head varieties. Residues on lettuce cultivars were higher than on the cabbages. The results clearly indicate that structure significantly affects residue deposit and dissipation, and pesticide recommendations cannot always be extended to specialty crops without an investigation of the changes in preharvest intervals to prevent violations of the maximum residue limits.

Representative commodity for five brassica vegetables based on the determination and dissipation of six pesticide residues

“…Residues in kale in this study were similar to those in leafy vegetables reported in relevant studies by Fan et al [1]. Study of nine pesticide residues on lettuce, cabbage and kale at different PHIs by Ripley et al showed that residues on lettuce and kale were both at high levels and significantly higher than those on cabbage [19]. Therefore, kale might be suitable to be classified in leafy vegetables.…”

Dissipation behaviour, processing factors and risk assessment for metalaxyl in greenhouse‐grown cucumber

“…The results of the present research were consistent with findings in the literature. The half‐life values of metalaxyl have previously been reported to be 4.9 days in grape, 7.8–8.7 days in tomato, 2.5 days in chinese cabbage and 3–3.5 days in cucumber fruits . The half‐life of metalaxyl was observed to be 1.3 and 0.4 days in tomato at single and double the application rate respectively .…”

Residualidad de fitosanitarios en tomate y uchuva cultivados en Quindío (Colombia)

“…Dentro de este grupo, se distinguen el Alfa, Gama, Delta-BHC, Heptacloro, Heptacloro epóxido, Aldrín, Endosulfán, 4,4´-DDE, 4,4´-DDD, 4,4´-DDT, Endrin y Endrin aldehído. Son altamente lipofílicos (solubles en grasa), no son biodegradables ni fotosensibles ni termolábiles, lo que les da una alta estabilidad y persistencia en el ambiente con una vida media de varios años (Fernández et al, 2012;Ripley, Ritcey, Harris, Denomme, & Lissemore, 2003). Asimismo, se destacan por su biomagnificación (aumento de la concentración a través de las cadenas tróficas) y por el hecho de ser neurotóxicos para el hombre y los animales (Ripley et al, 2003;Tao et al, 2005).…”