Overwaaien van bestrijdingsmiddelen naar waterlopen bij bespuiting in de bloembollenteelt

Het overwaaien van bestrijdingsmiddelen bij bespuitingen in de bloembollenteelt, als mogelijke bron van verontreiniging van waterlopen, is onderzocht. De methoden voor het meten van de depositie van de voorbeeldstoffen esfenvaleraat, chloridazon en Brilliant Sulfoflavine op verschillende collectoren zijn getoetst. In de drie veldproeven nam de aërieke depositie buiten het gewas af tot respectievelijk 0,6%, 0,9% en 2,1% van de dosering op de benedenwindse slootrand (op 3 u 4 m afstand). De aërieke depositie op het wateroppervlak (op ongeveer 5 m afstand) lag rond 0,5% van de dosering. Een spuitvrije zone van 4 u 5 m breedte levert een grote bijdrage aan het verminderen van overwaaien van spuitvloeistof naar de waterlopen

Volatilization of tri-allate, ethoprophos and parathion measured with four methods after spraying on a sandy soil

At about eleven times after application of tri-allate, ethoprophos and parathion to a sandy soil, their rates of volatilization were determined by the aerodynamic method (AD), the Bowen-ratio method (BR), the theoretical-profile method (TP) and the Box method. The volatilization was highest for tri-allate and lowest for parathion. On the first day after application, the volatilization rate decreased sharply, but thereafter the decrease was more gradual. The differences in volatilization rate as determined with the AD, BR and TP methods were comparatively small. The rates determined with the Box method were mostly lower than those determined with the other methods

Volatilization of parathion and chlorothalonil after spraying onto a potato crop

At fourteen times after application of parathion and chlorothalonil to a potato crop their rates of volatilization were determined by the aerodynamic and Bowen ratio methods. The highest volatilization rate of parathion occurred shortly after application. In the first hours after application its volatilization rate decreased sharply; thereafter it decreased more gradually. The volatilization rate of chlorothalonil at one week after application did not differ much from that shortly after application. Weather conditions in the first twenty-four hours after application of both pesticides were simulated in a chamber. The volatilization of parathion in the chamber had the same order of magnitude as that determined in the field

Transformation of aldicarb sulfoxide and aldicarb sulfone in four water-saturated sandy subsoils

Accurate transformation rates of pesticide residues in aquifer material are needed to predict the ultimate effects of pesticide leaching on drinking-water resources. Even slow transformation rates in the groundwater zone can lead to substantial reduction of the concentrations. In this study the transformation of the oxidation products of aldicarb was studied in incubations with water-saturated subsoils collected at four sites in the Netherlands. The transformation rates and products varied with soil type, redox potential, and the concentration of the products. The transformation was very fast in an anaerobic subsoil (half-lives some weeks) but much slower (one to several years) in more aerobic subsoils

Development and duration of accelerated degradation of nematicides in different soils

The development and duration of accelerated degradation of nematicides were studied in incubation experiments with soils from three experimental fields that had been treated annually for three to ten years with aldicarb, oxamyl, ethoprophos, fenamiphos or 1,3-dichloropropene. Highly accelerated degradation rates were measured for aldicarb, oxamyl and ethoprophos in a sandy soil (pH 7.3) treated three times. After five years without further treatments, these high rates were still found for aldicarb and oxamyl, but not for ethoprophos. In another field (sandy soil, pH 5.6) little or no increase in the degradation rates was measured in plots that had been treated ten times

Vervluchtiging van EPTC, tri-allaat en parathion na bespuiting van een kleigrond

Op tien tijdstippen na de bespuiting van een onbegroeide kleigrond met EPTC, tri-allaat en parathion werden de snelheden van vervluchtiging van deze middelen bepaald met de kapmethode en de theoretisch-profielmethode (TP-methode). De vervluchtiging was het hoogst op de dag van toepassing. In de daaropvolgende droge periode was de vervluchtigingssnelheid relatief laag. Veertien dagen na toepassing nam de vervluchtigingssnelheid toe doordat de toplaag van de bodem was herbevochtigd door regen. Gemiddeld was de snelheid van vervluchtiging bepaald met de TP-methode lager dan die bepaald met de kapmethode, maar het verschil was niet eenduidig