Regulators and traders around the world need internationally accepted, economical, and environmentally friendly treatment options to sanitize wood and allow its safe trade. With methyl bromide being phased out by 2015 (Montreal protocol) and severely restricted in some countries, including Canada, new treatments are needed to support international trade. A promising alternative fumigant, phosphine, is more environmentally friendly, easier and safer to use, and cheaper than methyl bromide. It is registered by the Pest Management Regulatory Agency for use on wood in Canada. However, specific efficacy data against pests associated with wood products are needed if phosphine is to be accepted through IPPC as a treatment recognized under ISPM-15 or ISPM-28. Over the last three years, FPInnovations has developed small-scale methods for evaluating fumigant efficacy using 10L glass jars that allow accurate control of temperature, fumigant concentration, and exposure time. These tests have shown that commercially suggested dosages for phosphine (200-500 ppm for 3-5 days at temperatures above 16°C) were not effective in killing pine wood nematodes, two species of bluestain fungi and one decay fungus. Nematodes and fungi also survived exposure to phosphine for 5 days at 800ppm, at 15 and 20°C. With additional funds received by CFS in 2011, we conducted additional tests where pine wood nematodes, two bluestain fungi and one decay fungus were exposed to the following concentrations of phosphine: 300, 600, 1000, 1500, 2000, 2500 and 3000 ppm over 5 days at 20°C and 25°C. The fungi were not killed with any of the combinations, while the number of nematodes was drastically reduced, but they were not fully eradicated.
Further work is needed to evaluate additional concentrations and times, and determine field feasibility in collaboration with international partners before we could advise the Canadian government whether a submission of efficacy data on phosphine to IPPC would be likely to succeed.