August 2000. Is dipping a more efficient quarantine treatment than spraying? This question was not answered, but it engendered discussion about dipping versus fumigation. It is generally agreed that dipping can only be done satisfactorily on small consignments of plants, if large, fumigation is the better way.
Dipping was developed as an alternative to MeBr fumigation when a number of plants were found to be susceptible to the fumigation treatment. In the 1970s, the treatment was DDT/malathion/white oil as a general purpose insecticidal treatment that would have toxicity to a wide range of arthropod pests. The current treatment recommendation substitutes carbaryl for DDT. The point is this is not as effective a treatment as MeBr. The AQIS recommendation is that if plants are dipped, they shoudl then be grown in PEQ and inspected. It is NOT a method to be used if pests are found on the plant when a visual inspected is done on arrival. If pest are detected, fumigation would be the normal treatment.
Not all plants tolerate dipping, although dipping is the preferred method spraying does not always give adequate coverage The whole of the plant should be dipped, including the roots. Some plants, like Tillandsia spp. can be damaged by the white oil component in dips. The oil blocks the air spaces. For these and related species, it is best to eliminate it from the dip. AQIS has information on the susceptibilities of plants to dips.
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