Fumigation of fresh herbs with phosphine as a new quarantine treatment


Abstract: Introduction of new pests into new habitats is the main concern of all agriculturalquarantine authorities. To prevent these dangers all countries enforce quarantine regulations onagricultural products demanding that the product will be free of live insect pests. To provide highquality products the fresh spices growers must market the harvested herbs within 3 days kept attemperature of about 4°C. Today exported herbs are fumigated with methyl bromide (MB) toachieve a total mortality of all insect developmental stages found in the products, MB is highlyphytotoxic and only effective as a pesticide when the fumigation is carried out at temperaturesover 21°C. To develop fumigation technology that will be suitable and effective to replace MB,experiments were carried out using phosphine. Experiments were carried out under laboratoryconditions at temperature of 4°C and for 24h exposure time. The tested herbs were: dill, parsley,tarragon, basil, mint, sage, oregano, thyme and rosemary. The insect pests: Laphigma spp.,Prodenia spp., Geometridae, thrips and Bemisia tabaci were collected at their adult and larvalstage with the herbs from the field and they were exposed to the phosphine fumigation treatment.The effective concentration of the gas that was found suitable to attain complete mortality of allgroups of tested insects was 700ppm. It was also found that the treatment killed alldevelopmental stages of mites Tetranychus urticae. Most herbs had no quality deterioration dueto the treatment even after 14d of storage, except basil and mint which were found sensitive tothe treatment. These results indicated that phosphine fumigation can be an effective quarantinetreatment that can control field insect pests after exposure of 24 hours at the low temperature of4°C and can be considered as MB alternative treatment.

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