Evaluation of methyl bromide alternatives to control thrips in orchid cut-flowers

摘要

Methyl bromide (MB) has been widely used as a pest control agent in various agricultural products including cut-flowers. MB is being phased out under the Montreal protocol due to its ozone depletion effect. Since the phase out has been planned to complete in 2015, investigation of alternatives to MB is urgently needed. In Thailand, all orchid cut-flowers are normally fumigated with MB for postharvest control of thrips before export. This project aimed to evaluate efficiency of other chemicals as MB alternatives. Phytotoxicity assessment of ethyl formate (25-100 g nr3), methyl formate (25-100 g nr3), acetaldehyde (0.05-0.2%) and phosphine (4-30 g nr3) on Dendrobium Sonia 'No. 17' was investigated. Fumigation with ethyl formate, methyl formate and acetaldehyde at all concentrations resulted in significant damages to orchid cut-flowers, while there was no damage in phosphine fumigation. Phosphine fumigation at 4 g nr3 for 1 h was sufficient to obtain 100% mortality of the second instar larvae of thrips. Our results demonstrated that phosphine fumigation showed great potential for quarantine treatment of orchid cut-flowers. Further research is required to determine the use of this chemical commercially.