BREAKDOWN OF INSECTICIDE GARDONA ON PLANTS AND IN SOILS

The breakdown of the insecticide ‘Gardona’ (2‐chloro‐1‐(2′, 4′, 5′,‐trichlorophenyl)‐vinyl dimethyl phosphate, previously known as SD 8447) has teen studied, on cabbages, apple foliage and fruit, and rice, and in soils, using radio‐isotope techniques under laboratory conditions. There was some isomerisation of ‘Gardona’ to its α‐isomer on foliage. the initial half‐life of ‘Gardona’ was about 1 day on the leaves and 4–5 days in medium loam soil. on foliage and in soils breakdown occurred by hydrolysis of the P‐O‐C bond to give initially 2,4,5‐trichlorophenacyl chloride and demethyl ‘Gardona’ followed by reactions of the former involving reduction of the ketone group and reductive dechlorination to form a number of eight‐carbon compounds. On foliage and on apple fruit the major breakdown products are conjugates of 1‐(2′,4′,5′‐trichlorophenyl)ethan‐1‐ol with sugars other than β‐D‐glucose. The breakdown products are of low toxicity to rats and, apart from the o‐isomer, none has insecticidal activity and none inhibits cholinesterase. Copyright © 1969 John Wiley & Sons, Ltd