Fumigation of Wheat Using Liquid Ethyl Formate Plus Methyl Isothiocyanate in 50-Tonne Farm Bins

Abstract

Australian Standard White wheat, Triticum aestivum L. (a marketing grade with mixed grain hardness),with a moisture content of 12.5% was fumigated with a new ethyl formate formulation (95% ethyl formate plus 5% methyl isothiocyanate) identified and developed by Commonwealth Scientific and Industrial Research Organization Entomology, Canberra, Australia. Wheat was fumigated with the formulation at a calculated application rate of 80 g/m3 in two 50-tonne sealed metal vertical silos located at Fisherman Islands, Queensland, Australia. Access was gained through the top of the silo where the application of the formulation was completed within a few minutes by pouring it onto the top of the wheat. After 2 h of recirculation, using a 0.5-kW fan, the in-bin concentrations of ethyl formate achieved equilibrium with a concentration variation < 7%. The ethyl formate concentration, in both silos 1 and 2, during the first day's exposure period remained above 10 g/m3. The concentration of ethyl formate by time product achieved was 790 and 650 g h/m3 in silos 1 and 2, respectively. In silo 1, the formulation was sufficient to kill all life stages of mixed age cultures of Sitophilus oryzae (L.), Rhyzopertha dominica (F.), and Tribolium castaneum (Herbst). In silo 2, control was 100% for R. dominica and T. castaneum and 99.4% for S. oryzae. After 5 d fumigation, the silo top-hatch was opened but no forced aeration was initiated. The in-bin concentration of ethyl formate was lower than the Australian experimental threshold limit value of 100 ppm. The ethyl formate and methyl isothiocyanate residues in the grain had declined to below the Australian experimental maximum residue limit of 0.2 and 0.1 mg/kg, respectively. The workspace and environmental levels of ethyl formate and methyl isothiocyanate were less than the detection limit of 0.1 ppm. The treatment with ethyl formate formulation had no affect on the wheat germination and seed color compared with untreated controls.

Concurrent application of ethyl formate and 1‐methylcyclopropene to control Tetranychus urticae on exported sweet persimmons (Diospyros kaki Thunb. ‘Fuyu’)

“…Its application has been reported successful as a cylinderized gas mixture of EF and carbon dioxide and as liquid EF mixed with water (Ren et al . ). Recently, a method has been developed for applying liquid EF with nitrogen gas by using a special vaporizer.…”

“…Ethyl formate has been developed as a fumigant for stored dried fruits since 1925, and its successful use has been reported in India and Australia since 1980 (Ryan and De Lima 2013). Its application has been reported successful as a cylinderized gas mixture of EF and carbon dioxide and as liquid EF mixed with water (Ren et al 2008). Recently, a method has been developed for applying liquid EF with nitrogen gas by using a special vaporizer.…”

Insecticidal Effects of Fumigants (EF, MB, and PH3) towards Phosphine-Susceptible and -Resistant Sitophilus oryzae (Coleoptera: Curculionidae)

“…It has been used for dry fruit insect control since 1927 and has also been used for the disinfection of cereals, stored dry beans, tomatoes, and preserved foods [27,28]. In the United States, pesticides have been registered [29] for the control of pests in storage products such as Tribolium confusum and Ephestia figuliella in raisins [30].…”

Ethyl formate plus methyl isothiocyanate—a potential liquid fumigant for stored grains

“…Metam sodium degrades in the soil to MITC, which in turn acts as a fumigant 18. Previous research has shown that MITC used in combination with EF can significantly reduce the dosage of EF required to concentrations below the flammablity level and result in effective fumigation 19. For example, adults of S. oryzae were unaffected by 5.9 mg L −1 of EF used alone for 24 h at 25 °C; however, with the addition of 5% MITC, there was an observed 99% mortality of S. oryzae adults, showing quite remarkable synergism between EF and MITC 19…”