A comparison of time and time-weather models for predicting parathion disappearance under California conditions

Nigg, H. N.; Allen, J. C.

doi:10.1021/es60150a001

Cited by 6 publications

(4 citation statements)

References 7 publications

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“…After correction for growth dilution, residue decline was adjusted for weather. A procedure similar to that of Nigg et al (1977bNigg et al ( , 1978Nigg et al ( ,1979a and Nigg and Allen 1979) was used to test different weather models. Using multiple linear regression (MLR), the micrograms of fenvalerate data and the weather data from the three field experiments were combined within an overall first-order model.…”

Section: Methodsmentioning

confidence: 99%

“…The first-order exponential model, the power rate model, the hyperbolic rate model, and the log residue-log time model have been described previously (Hamaker, 1972; Goring et al, 1975; Agriculture Canada Research Station, Lethbridge, Alberta, Canada TU 4B1. Nigg et al, 1977a; Stamper et al, 1979). One method to improve the accuracy of residue predictions is to adjust for weather variables.…”

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confidence: 99%

“…One method to improve the accuracy of residue predictions is to adjust for weather variables. Nigg et al (1977a) have reviewed several successful weather models of pesticide disappearance. In the study of ethion decay in Florida citrus, Nigg et al (1977b) assumed the effect of different weather variables to be linear and additive within an overall first-order model.…”

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confidence: 99%

“…The resultant multiple linear regression using time and weather accounted for 94% of the observed residue variation, compared to only 57% of the variation explained without the weather variables. The same type of multiple linear regression time-weather model has been used effectively for other pesticides on citrus (Nigg et al, 1978(Nigg et al, , 1979b; Nigg and Allen, 1979). In one study (Nigg et al, 1979a), the decline of parathion residues on Florida oranges was so related to weather variables that the time variable was not required in the overall model.…”

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Persistence of fenvalerate in alfalfa: effect of growth dilution and heat units on residue half-life

Hill¹,

Charnetski²,

Schaalje³

et al. 1982

J. Agric. Food Chem.

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Fenvalerate [cyano(3-phenoxyphenyl)methyl4-chloro-a-(l-methylethyl)benzeneacetate] was applied to alfalfa at 0.14-0.15 kg/ha in three experiments, and the residues, crop growth, and weather were monitored for 28 days. Initial residues of 22.2-32.5 ppm declined exponentially with a half-life of 9-11 days. When fenvalerate was applied early in the season, the advantage of growth dilution of the residues was negated by cooler temperatures slowing the rate of decline of the chemical itself. The half-life of the chemical per se, with the effect of growth dilution removed, was 11-19 days, depending on the weather after application. Cumulative heat units were used to correlate residue decline to both time and temperature, and the concept of residue half-life in degree-days was introduced. The result was a half-life of 153-189 degree-days above 5 "C for fenvalerate residues in alfalfa.Fenvalerate [cyano(3-phenoxyphenyl)methyl4-chloroa-(l-methylethy1)benzeneacetatel is one of the synthetic pyrethroid insecticides being evaluated at this laboratory for the control of weevils (Hypera postica Gyll.) and Lygus spp. in alfalfa (Charnetski and Schaber, 1980a,b). One concern is that fenvalerate residues are potentially toxic to bees. The National Research Council Canada (1981) rates fenvalerate as highly toxic to honeybees (Apis mellifera L.), LDm = 0.408 pg/bee, and as hazardous to the alfalfa leafcutter bee [Megachile rotundata (F.)] any time application is made during flowering. The leafcutter bee is the primary pollinator of alfalfa grown for seed, and the need to spray insecticides to control high populations of insect pests often occurs close to the start of alfalfa flowering (June 20-30). After flowering, there is little growth of the alfalfa to dilute the insecticide residues, and the amount of insecticide to which the bees are exposed will depend on the persistence of the chemical residue. Thus, information on residue persistence is required to help establish a safety interval between insecticide application and placement of leafcutter bees in the field.There have been few published reports on the persistence of fenvalerate in field crop situations. Harris et al. (1978) applied fenvalerate at 0.14 kg/ha to celery grown in outdoor microplots. Residue levels were 3.3, 1.7,0.45, and 0.36 ppm after 0, 7, 14, and 21 days, respectively. Westcott and Lee (1978) reported a ht-order decline with a half-life of 5 days for fenvalerate residues on wheat foliage. This rate of residue decline included a large growth dilution effect of the crop. Greenberg (1981) described a method for determining fenvalerate in grapes, peppers, and apples and presented residue data from field-treated samples. Although half-lives were not calculated, initial residues declined by half within 14 days. However, when fenvalerate was sprayed on grapes and peppers at higher rates, there was no residue decline within 14 days.The half-life concept, derived from first-order kinetics (Gunther and Blinn, 1955;Gunther, 1969;Hamaker, 1972), is commonly used to d...

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

mentioning

confidence: 99%

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Persistence of fenvalerate in alfalfa: effect of growth dilution and heat units on residue half-life

Hill¹,

Charnetski²,

Schaalje³

et al. 1982

J. Agric. Food Chem.

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Möglichkeiten der Anwendung mathematischer Verfahren zur Interpretation des Rückstandsverhaltens von Pflanzenschutzmitteln

Goedicke

Edlich

1985

Nahrung

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Für die hygienisch‐toxikologische Bewertung von Pflanzenschutzmitteln (PSM) sind umfangreiche Untersuchungen zum Rückstandsverhalten der Wirkstoffe auf bzw. in Pflanzen erforderlich. Die Rückstandsdynamik eines Wirkstoffes läßt sich graphisch als Konzentrations‐Zeit‐Kurve darstellen. Zur Quantifizierung des Rückstandsverhaltens und Auswertung von Rückstandsdaten können solche funktionellen Zusammenhänge angewendet werden, die eine Darstellung des Abbaus der Rückstände in mathematischer Form ermöglichen. Das Rückstandsverhalten kann weiterhin durch die Berechnung von Halbwertszeiten für die jeweiligen Bedingungen charakterisiert werden. Ausgehend von Angaben in der Literatur und eigenen Erfahrungen, werden derartige mathematische Ansätze für die Beschreibung des Rückstandsverhaltens dargestellt. Für Routineuntersuchungen zur rückstandstoxikologischen Bewertung von PSM läßt sich der zeitliche Abbau der Rückstände nach einer Reaktion 1. Ordnung graphisch und rechnerisch gut beschreiben, wobei der mathematische Aufwand relativ gering ist.

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Zum Rückstandsverhalten von Fenazox auf Pflanzen 2. Mitt. Rückstandsverhalten von Fenazox auf Tomaten und Blattoberflächen

Goedicke

Sieber

Link

1983

Nahrung

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Auf Grand der Erweiterung der Zulassung von „Fentoxan”︁ erfolgt der Einsatz des Präparates auch im Tomatenanbau. Unter Berücksichtigung der Versuchsdurchführung in der 1. Mitt. wird eine Methode zur Ermittlung von Oberflächenrückständen auf Tomatenblättern beschrieben. Die Nachweisgrenze der gaschromatographischen Bestimmung betragt 10 ng/cm2. Es wird das Rückstandsverhalten von Fenazox nach Kaltvernebelung von „Fentoxan”︁ auf Tomatenfrüchten und ‐blättern diskutiert. Die Rückstandsdaten werden durch lineare halblogarithmische Regressionsanalyse nach einer Reaktion 1. Ordnung ausgewertet. Die Halbwertszeiten betragen unter den genannten Versuchsbedingungen für Fenazox auf Tomatenfrüchten 1,4 Tage und auf Tomatenblattern 2,3 Tage. Zur Gewährleistung der lebensmittelhygienischen Qualitat der Tomatenfrüchte beim Kaltnebelverfahren sind für die Aufwandmengen 0,3 ml/m2 und 0.5 ml/m2 Karenzzeiten von 4 bzw. 7 Tagen und beim Spritzverfahren von 14 Tagen erforderlich.

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A comparison of time and time-weather models for predicting parathion disappearance under California conditions

Cited by 6 publications

References 7 publications

Persistence of fenvalerate in alfalfa: effect of growth dilution and heat units on residue half-life

Persistence of fenvalerate in alfalfa: effect of growth dilution and heat units on residue half-life

Möglichkeiten der Anwendung mathematischer Verfahren zur Interpretation des Rückstandsverhaltens von Pflanzenschutzmitteln

Zum Rückstandsverhalten von Fenazox auf Pflanzen 2. Mitt. Rückstandsverhalten von Fenazox auf Tomaten und Blattoberflächen

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