The overall goal of this USDA-ARS research is to ensure the protection and quality of stored product foodstuffs. The results of this research directly enhance production, distribution, and safety of foodstuffs, promote and retain access of United States-grown crops to domestic and foreign markets, and protect the United States and trading partners from the agricultural, ecological, and economic threat posed by quarantine and invasive pests. In general, USDA-ARS research related to the fumigation of stored products focuses on the development of techniques to rapidly disinfest raw products of field pests, control pests in processed products amenable to re-infestation and microbial infection, and reduce reliance on fumigation as a stand-alone measure for postharvest disinfestations and disinfections. Specific research objectives include: comparative evaluation of alternative fumigants to methyl bromide in postharvest applications, development of novel technologies to reduce and eliminate atmospheric emissions from chambers used in postharvest fumigation, and design production strategies that allow for a more strategic postharvest use of methyl bromide and alternative fumigants. Recent research findings will be presented and discussed.

The bulb mite (BM), Rhizoglyphus echinopus, is hard to control in the harvested onion and garlic. Methyl bromide (MeBr) fumigation is the only option to eradicate BM at present. However, MeBr causes phytotoxic damage (index 3) to onion and garlic and highly toxic to fumigators. To replace MeBr, we evaluated ethyl formate (EF) and phosphine gas (PH3) to BM at 5℃ which is current practical fumigation temperature. The >140 g·h m-3 of EF for 24 h could completely control BM and this CT (concentration × time) product was slightly (index 1) phytotoxic to onion and garlic. Fumigation of 2 g PH3 required >120 h exposure to kill 100% of BM without any pyhtotoxic damage. Further researches are being planned to shorten the exposure time with synergistic effect between EF and PH3.

Aphids are common pests frequently found in imported and exported fruits and vegetables. Methyl bromide(MB), a Quarantine and Pre Shipment(QPS) fumigant, could offer eradication of aphids within short period. However, MB is limited in use because of poor gas evaporation at low temperature(<5℃) and there is phytotoxic effect or damage on quality in post-harvest vegetables and fruits even at >5℃. Two candidates of MB alternative, ethyl formate(EF) and phosphine(PH3), are used and being investig at edonvarious fruits and vegetables fumigation to replace MB. Aphids are known as quarantine pest that are hard to control when conduct short period fumigation with PH3 and low dosage of EF. In this paper, dose response assessment of EF and PH3 are presented for three different aphid pecies : cotton aphid(Aphisgossypii), green peach aphid(Myzuspersicae) and turnip aphid (Lipaphiserysimi). The LCt99% values of EF at room temp. and low temp. (5℃) were 4.42 and 4.45 g·h·m-3 for cotton aphid, 3.23 and 5.58 g·h·m-3 for turnip aphid, 3.23 and 5.58 g·h·m-3 for green peach aphid when 2-hours fumigation. PH3 showed 0% efficacy on all species when 2-hours fumigation.

With the increasing trend of global trades and protection of agro-ecosystem in importing and exporting countries against quarantine pest, quarantine and pre-shipment(QPS) fumigation in perishable commodites like strawberry is critical in terms of quality maintenance of fumigated commodites. Currently, there are limited use of MB fumigation on fruits and vegetables due to low temperature storage and phytotoxic effect or damage in postharvest qualities in many commodites. In this paper, efficacy and quality accessment of methyl bromide(MB) alternatives, ethyl formate and phosphine gas are presented for export strawberry. Efficacy of phosphine gas and ethyl formate are described in terms of concentration × time (CT) products to Frankliniella occidentalis, Aphis gossypii and Myzus persicae.