Fumigation of edible cut flowers with ethyl formate mixed with CO2

Abstract: The Western flower thrips, Frankliniella occidentalis (order Thysanoptera) is a
thrips species that represent major plant pests. It is a polyphagous species capable of adversely affecting crop production. As such, in the European Union, these thrips species are regulated as quarantine organisms. F. occidentalis can cause considerable damage to susceptible plants by feeding on them and transmitting several viruses responsible for serious plant diseases. Israel is responsible for 50 % of the fresh herbs market in Europe, among them is considered the edible cut flowers market. However, phytosanitary failures due to quarantine pests with no optional treatment to control them, in the past decade, reduced significantly export volumes. Up to day, there is no effective disinfestation post-harvest treatment. Due to its association with the depletion of the ozone layer, the fumigant methyl bromide (MB) has been phased out and today is serving as a Quarantine and Pre-Shipment fumigant. However, MB is known for its phytotoxic character, especially on leafy products and foliage. Ethyl formate (EF) was suggested as an alternative to MB due to its rapid action, low mammalian toxicity, being benign to the environment, and its rapid breakdown with minimum or no residues. Trials conducted in Israel on various flower species treated with 30 g/m3 EF mixed with CO2 (1:6 ratio) at 1, and 1.5 h in 10 and 15 °C obtained high efficacy in controlling all life stages of F. occidentalis. In 2 h exposure time at 15 °C resulted in complete mortality with no adverse effects on the flowers or their shelf lives. EF fumigation was found as a suitable treatment for quarantine purposes and as an appropriate alternative to Methyl bromide.