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As part of experiments to evaluate naturally occurring volatile compounds as fumigants to reduce microbial populations, especially pathogenic fungi on strawberry fruit, several test compounds were found to be metabolized by the fruit to yield additional volatile compounds. The natural products used as fumigants comprised alcohols, aldehydes, ketones, esters, and hydrocarbons and were tested with fruit in closed containers at refrigeration (2-4°C) temperatures. The three principal types of volatile metabolites formed by strawberry fruit as determined by GC and GC-MS analyses of headspace vapor samples were esters produced from aliphatic alcohols [e.g., (Z)-3-hexenyl acetate from (Z)-3-hexen-1-ol], alcohols formed by the reduction of aliphatic aldehydes (e.g., 1-hexanol from hexanal), and saturated products from reduction of carbon-carbon double bonds conjugated with an aldehyde or ketone carbonyl moiety [e.g., 2-nonanone from (E)-3-nonen-2-one]. Metabolic pathways leading to the formation of the volatile products and applications for the metabolites are discussed.

: Endosulfan (Thiodan 3 EC), a mixture of a-and b-isomers, was sprayed on 92-day-old Ðeld-grown pepper and tomato at the recommended rate of 0É61 kg AI ha~1. Plant tissue samples were collected at 1 h to 14 days after application and analysed to determine the content and dissipation rate of endosulfan isomers (a-and b-endosulfan) and the major metabolite, endosulfan sulfate. Analysis of samples was accomplished using gas chromatography-mass selective detection (GC-MSD). The results indicated the formation of endosulfan sulfate as a residue component on the plant tissues and also the relatively higher persistence of the b-isomer as compared to the a-isomer on pepper fruits. The initial total residues (a-and b-endosulfan isomers plus endosulfan sulfate) were higher on leaves than on fruits. On pepper fruits, the a-isomer, which is the more toxic to mammals, dissipated faster than the less toxic b-isomer. Total residues (a-and b-endosulfan isomers plus the sulfate metabolite) on tomato leaves revealed longer persistence 4É6 days) compared to the total residues detected (t 1@2 on pepper leaves 2É0 days) 3È14 days following spraying. Persistence of the (t 1@2 b-isomer on pepper fruits was high 3È14 days following spraying compared to on tomato fruits. This long persistence increases risk of exposure of the consumer. In addition, the longer persistence of the total residues on tomato foliage should be considered of importance for timing the safe entry of tomato harvesters due to the high mammalian toxicity of endosulfan.1998 Society of Chemical ( Industry Pestic. Sci., 54, 61È67 (1998)

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