Characterization of methomyl dissipation on grape foliage

Reeve, Matthew W.; O’Connell, Linda; Bissell, S.; Ross, John H.

doi:10.1007/bf00193348

Cited by 8 publications

(6 citation statements)

References 2 publications

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“…The MRL value of methomyl residues in lettuce is suggested to be 5 mg kg -1 (Global MRL Database 2015). In the present study, the residue concentrations of methomyl, at 2.6 mg kg -1 , were below the MRL 1 day after treatment (Table 2); at 5.1 days, its half-life is in agreement with results obtained by Reeve et al (1992), which showed that variable half-lives of methomyl in grape foliage in 36 U.S. fi elds ranged from 1 to 7.7 days. In contrast, the half-life of methomyl in qat leaves, as demonstrated in our study, is longer than the reported half-lives in other studies of other plants e.g., 0.9-1.34 days for tomatoes (Gambacorta et al, 2005;Malhat et al, 2015) and 0.88-0.94 days for okra fruits (Aktar et al, 2008).…”

Section: Resultssupporting

confidence: 91%

“…In contrast, the half-life of methomyl in qat leaves, as demonstrated in our study, is longer than the reported half-lives in other studies of other plants e.g., 0.9-1.34 days for tomatoes (Gambacorta et al, 2005;Malhat et al, 2015) and 0.88-0.94 days for okra fruits (Aktar et al, 2008). The half-life of methomyl in plants increases signifi cantly with the progression of the summer months (Reeve et al, 1992) due to the slow growth of plants and, consequently, less effi ciency in the degradation of the pesticides. The initial residual concentration in qat leaves was higher than results reported in tomatoes (1.54 mg kg -1 ) (Gambacorta et al, 2005) and 5.61-8.42 mg kg -1 in okra fruits treated at the recommended and double-the-recommended doses, respectively (Aktar et al, 2008).…”

Section: Resultscontrasting

confidence: 71%

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Persistence of imidacloprid, acetamiprid and methomyl in qat leaves

Al-Rajab

Alhababy²,

Alfaifi

2016

Hellenic Plant Protection Journal

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Summary Qat leaves are chewed on a daily basis by approximately 10 million inhabitants of different countries. This study investigated the persistence of three insecticides most used in qat production, imidacloprid, acetamiprid and methomyl. These chemicals were applied separately on plots of ten qat trees each at the recommended application rates. Samples of qat leaves were collected separately at time 0 (1 h post-treatment) and 1, 3, 7, 12, 19, 26 and 37 days after application. The residues of the investigated pesticides were extracted and then quantified by liquid chromatography (LC-MS/MS). The half-lives of imidacloprid, acetamiprid and methomyl were 12.2, 11.7, and 5.1 days, respectively. Overall, our findings showed that imidacloprid and acetamiprid were more persistent than methomyl in qat leaves. Taking into account the maximum residue limits (MRL) in lettuce, due to lack of MRL in qat leaves, the residue concentrations were below MRL for imidacloprid 7 days after application, and 1 day after application for acetamiprid and methomyl.

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Section: Resultssupporting

confidence: 91%

Section: Resultscontrasting

confidence: 71%

Persistence of imidacloprid, acetamiprid and methomyl in qat leaves

Al-Rajab

Alhababy²,

Alfaifi

2016

Hellenic Plant Protection Journal

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“…The observed DT50 of methomyl observed on spinach (3.11days) fits into the range of half-lives of methomyl on growing foliage (1-7 days) reported by [23,31]. Also, methomyl half-lives were 1.34 and 1.1867days on tomato fruits [3,20].…”

Section: Dissipation Of Chlorfenapyr and Methomyl In Spinachsupporting

confidence: 76%

Chlorfenapyr and Methomyl Deterioration on Spinach Plants and Their Residual Effects in Vitro on Egyptian cotton Leafworm (Spodoptera littoralis)

Fetoh¹,

Ramadan²,

Ali³

2021

JNFP

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Field trials conducted to determine the degradation of chlorfenapyr and methomyl insecticides in/on spinach leaves. Spinach plants sprayed with chlorfenapyr (Challenger Super™ 24% SC) and methomyl (Neomyl™ 90% SP) at the rates of 50 cm3/100 L water and 715 g/ ha, respectively. The QuEChERS method used for the extraction and clean-up of the samples. Residue amounts determined at 2 h, 2, 4, 6, 9, 13 and 16 days after application by UHPLC-UV. The mean of recovery percentages was 98.78 and 99.05 % for chlorfenapyr and methomyl, respectively. The initial deposits of chlorfenapyr and methomyl on/in spinach leaves, two hours after a single application of the insecticides were 23.17 and 235.37 mg/kg, respectively. The percentages of dissipation of chlorfenapyr were 37.68, 55.29, 69.45, 84.45 and 96.83% for 2, 4, 6, 9 and 16 days after application. The corresponding dissipation percentages of methomyl were 38.27, 56.01, 71.44, 84.34 and 97.81%. The rates of degradation (k values) were 0.212 and 0.223, while the corresponding half-life times (t0.5) were 3.27 and 3.11 days with chlorfenapyr and methomyl, respectively. It could be recommended that single application of chlorfenapyr on Spinach plants at the early ages followed by single application of methomyl at least 17 days before harvest.

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“…Increasing temperature is known to accelerate numerous processes involved in pesticide dissipation 10,27,159 by, for example, increasing a substance's solubility. 10 Effects of temperature on the dissipation of pesticides in plants have been assessed by four studies qualitatively (mainly discussing seasonal aspects with respect to growing seasons) 134,163,175,176 and by 18 studies quantitatively, 69−71,73,74,119,137,157,174,177−185 of which 14 studies explicitly investigated the influence of cold storage conditions. 70,71,73,74,119,137,157,177−183 The effect of reduced temperatures in cold storage rooms varies significantly ranging from reduced dissipation of carbendazim in mango fruits by a factor 2 during storage at 15 °C (the corresponding average temperature in the field study was 25 °C) 179 to reduced dissipation of pyriproxyfen in bell pepper fruits by a factor 24 during storage at 4 °C (the corresponding average temperature in the field study was 24 °C).…”

Section: Aspects Influencing Pesticide Dissipationmentioning

confidence: 99%

Variability of Pesticide Dissipation Half-Lives in Plants

Fantke¹,

Juraske

2013

Environ. Sci. Technol.

291

183

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Information on dissipation kinetics of pesticides in food crops and other plants is a key aspect in current risk and impact assessment practice. This is because human exposure to pesticides is predominantly caused by residues in agricultural crops grown for human and animal consumption. However, modeling dissipation of pesticides in plants is highly uncertain and therefore strongly relies on experimental data. Unfortunately, available information on pesticide dissipation in plants from experimental studies only covers a small fraction of possible combinations of substances authorized for use on food and fodder crops. Additionally, aspects and processes influencing dissipation kinetics are still not fully understood. Therefore, we systematically reviewed 811 scientific literature sources providing 4513 dissipation half-lives of 346 pesticides measured in 183 plant species. We focused on the variability across substances, plant species and harvested plant components and finally discuss different substance, plant and environmental aspects influencing pesticide dissipation. Measured half-lives in harvested plant materials range from around 1 hour for pyrethrins in leaves of tomato and pepper fruit to 918 days for pyriproxyfen in pepper fruits under cold storage conditions. Ninety-five percent of all half-lives fall within the range between 0.6 and 29 days. Our results emphasize that future experiments are required to analyze pesticide-plant species combinations that have so far not been covered and that are relevant for human exposure. In addition, prediction models would help to assess all possible pesticide-plant species combinations in the context of comparative studies. The combination of both would finally reduce uncertainty and improve assumptions in current risk and impact assessment practice.

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Characterization of methomyl dissipation on grape foliage

Cited by 8 publications

References 2 publications

Persistence of imidacloprid, acetamiprid and methomyl in qat leaves

Persistence of imidacloprid, acetamiprid and methomyl in qat leaves

Chlorfenapyr and Methomyl Deterioration on Spinach Plants and Their Residual Effects in Vitro on Egyptian cotton Leafworm (Spodoptera littoralis)

Variability of Pesticide Dissipation Half-Lives in Plants

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