Fumigation of fruits and vegetables during quarantine and pre-shipment (QPS) treatment should be effective with a shorter fumigation time to minimize phytotoxicity. In this research study, a shorter fumigation time, 2 hours exposure which is shorter than that of the current commercial fumigation procedures using a lower dose of ethyl formate (EF) mixed with phosphine (PH3) on strawberry was investigated. The reciprocal effect between EF and PH3 against nymphs and adult Myzus persicae (Sulzer) and Tetranychus urticae (Koch) was evaluated. In addition, L(Ct)50 and L(Ct)99 of EF only and EF mixed with PH3 were analyzed at 5°C and 20°C. The synergistic ratio (SR) of L(Ct)50 and L(Ct)99 for the nymph and adult stages of M. persicae were >1.0, which indicated a synergistic effect between EF and PH3. However, the SR values of L(Ct)50 and L(Ct)99 of the nymph and adult stages of T. urticae were ≤1.0 indicating that there was no synergistic effect between the two fumigants against T. urticae. Our results showed that the reciprocal effect between EF and PH3 has different effects on M. persicae and T. urticae. This could be attributed to the biological and physical differences between the class Arachnida and Insecta. The synergistic effect between EF and PH3 against M. persicae within a shorter exposure period and without phytotoxicity on fruits and vegetables will significantly benefit the horticultural industry.

Methyl Bromide (MB) has been regulated by montreal protocol due to ozone depletion since 1992, and there is a need to develop MB alternative fumigation methods. To find out the efficacies and tolerance in developmental stages of citrus mealybugs (Planococcus citri) which frequently infested in imported pineapples, phosphine(PH3) gas was tested in different exposure times (2~24 hr) and concentrations (0.1∼2g/m3) in small desiccators at 8℃. Based on Lethal 99% concentration × time products (LCTP 99%) of PH3 gas to target developmental insect, 2g/m3 PH3 was applied for 24 hr in 300 m3 fumigation facility, which was designed in well sealed and evacuation system (5 air exchange/min). We monitored PH3 gas in fumigation facility to confirm CTP and checked PH3 gas in atmospheres in air ventiliation process after fumigations to make quarantine guideline and protocol for worker safety as well as efficacy to target pest.

For replacement of methyl bromide(MB) in Korea, VapormateTM, a gas formulation of ethyl formate(EF) with carbon dioxide, are firslty introduced in import bananas and VivakilTM, a gas formulation of phosphine(PH3) with carbon dioxide, are ready to commercial use in export cut flowers. Their applications are being extended for other import and export commodities. Ethyl formate have been shown to have effectiveness short exposure time(<4hr) but it has a limited application at low temperature for TSM(Two spotted spider mites) due to some phytotoxic to strawberry. Phosphine gas has demonstrated their efficacy to TSM at low temperature but only meets quarantine requirement when applying longer fumigation time(>24hr) to control CA(cotton aphids). We firstly evaluated two MB alternatives, EF and PH3, have enhansive effect within short exposure time(4hr) at low temperature(5℃) for controlling both TSM and CA without any injury to export strawberries.

Methyl bromide (MB) has been banned by Montreal Protocol due to ozone depletion in developed countries since 2005 but uses for quarantine & pre-shipment (QPS) remains exemption. Current MB alternatives such as phosphine gas, ethyl formate has been showing their potential in terms of their no phytotoxic damages to target perishable commodities post fumigation as well as their efficacy at low temperature. We evaluated phosphine (PH3) gas as MB alternatives welsh onion, carrot, and lettuce fumigation. on sensitivity test, larvae of Aphis gossypii were most tolerant to PH3 among the all stage of A. gossypii, Tetranychus urticae and Plutella xylostella. The LC99 and LCT99 value of mixture gas for adult of A. gossypii was 1.79 mg/L (24hr, 5℃) and 33.56 mg h/L(5℃), respectively. On confirmation trials scheduled in 28m3 container for 24hr at 5℃, all stages of T. urticae was completely controlled in 2g/㎥ of phosphine gas, but A. gossypii and M. persicae were not completely controled. No phytotoxic damage was observed in vegetables.