Commercially grown cotton and potted cotton plants were sprayed with five pesticides, and simulated rain was applied 1–72 h later. Leaf samples were analysed to determine the effect of the rain on the original deposits. It was found that 2 to 5 mm of simulated rain applied 1 h after spraying, washed off 50% or more of the original deposit. An increase in rainfastness of the pesticides occurred over a period of time after spraying. The type of formulation seemed to affect rainfastness, but the origin of a formulation, the addition of wetting agents and the intensity of the simulated rain did not.

No abstract

A simple rapid bioassay is described for the determination of biologically available bromacil residues in soils. A clear aqueous extract was made from a soil fortified with a known amount of the herbicide, and similar extracts were made from samples of soil taken from plots that had been sprayed with a bromacil formulation at a rate of 4 kg ha−1. Samples of these extracts were added to a suspension of the unicellular green alga Selenastrum capricornutum. The net photosynthetic oxygen production by the alga was then measured using an oxygen electrode. The results were expressed as a percentage of the oxygen production by a control suspension. The concentration of biologically available bromacil was determined by reference to a previously established dose‐response curve of the percentage reduction in oxygen production against bromacil concentration. The accuracy of this bioassay was determined by comparing the results with those obtained using capillary gas‐liquid chromatography. The results obtained by the two different methods showed good agreement.

Residues of aldicarb and fenamiphos [parent compound, sulfoxide, and sulfone metabolites analyzed as sulfone and expressed as total aldicarb (TA) or total fenamiphos (TF)] in the roots, soil, leaves, and fruit from vineyards were determined with a gas chromatograph equipped with packed columns. Temik (aldicarb) granules at 5 kg/ha and Nemacur (fenamiphos) granules at 20 kg/ha were applied either in scatter over the entire area (broadcast) or in 20-cm bands on either side of the rows of vines. No residues

Six auxin-type herbicides in air, rain and dew samples were extracted and derivatised t o the volatile 2,3,4,5,6-pentafluorobenzyl derivatives, followed by confirmation and quantification using gas chromatography with ion trap detection. The extraction recovery of 2,4-dichlorophenoxyethanoic acid and its dimethylamine salt from fortified tubes (air samples), distilled water (rain samples) and filter-paper (dew samples) was acceptable. The powerful selectivity of the gas chromatograph with ion trap detection allowed quantification of the herbicides irrespective of extraneous peaks present at the same retention time. In addition, automatic confirmation was accomplished without using a mass spectrometer. For 2,4-dichlorophenoxyethanoic acid, the method has a limit of detection of 0.72 ng m-3 in air, 8.39 ng 1-1 in rain water and 5.21 ng per 491 cm2 of exposed filter-paper (dew sample).