Safeguarding Australian exports logs – methyl bromide

Australian log exports rely on the fumigant methyl bromide (MB) to control pests and meet the phytosanitary requirements of key markets such as China and India. However, MB was banned internationally for specific uses under the United Nation’s Montreal Protocol because it degrades stratospheric ozone. There is increasing international pressure to cease use of MB for other purposes, such for export logs. For example, the European Union have banned the use of MB for all treatments including quarantine, and other countries like New Zealand mandate the recapture and destruction of the compound.

Work Safe Australia recently reviewed the use of fumigants including MB and changed its time-weighted average (TWA) value from 5 to 1 ppm. Practically, the TWA value guides the safety standards and operational procedures imposed by government for MB fumigations. Therefore, the APVMA will need to review the buffer zone distances and recapture requirements associated with MB use before the new TWA values come into place on December 1, 2026. Increased buffer zones for MB use could have massive implications for Australian log export, as seen in New Zealand where they increased up to 700 m. Therefore, industry urgently needs strategic directions to address the risk of MB withdrawal and restrictions on its use, especially new research on alternative treatments.

In response, Forest and Wood Products Australia funded work led by VSICA Research to address these issues and provide strategic direction for industry. The project aims to:

1. Review all potential MB alternatives for log export,
2. Evaluate the current international regulatory environment and risk of MB phase-out,
3. Consult exporters and fumigators to benchmark current MB use in logs and identify potential barriers to adoption of alternative treatments,
4. Conduct proof-of-concept research on a new ozone-friendly alternative (methyl iodide) with equivalent effectiveness and application technology to MB, and
5. Design a strategic research program for FWPA on alternative(s) for industry.

As part of the project, VSICA Research have already completed an extensive literature review of 114 international studies published in the scientific literature on alternative treatments to MB for control of pests in export logs.

The review identified the advantages and disadvantages of different treatments including their relative cost, with the fumigants methyl iodide, ethanedinitrile, sulfuryl fluoride, and phosphine emerging as short-term prospects, and joule and microwave heating as longer-term solutions. Preliminary field experiments conducted in Portland, Victoria showed that methyl iodide killed natural and surrogate pest populations in log stacks very effectively. Though more research is required, early data also showed that methyl iodide can kill wood wasp larvae (Sirex noctilio) in logs, which is an important quarantine pest for Australia’s trading partners (Fig 1).

If you are interested in learning more about the research project or have any questions relating to the topics discussed, please email Dr. Dylan McFarlane at dylan.science@outlook.com.

Source: Dr. Dylan McFarlane (VSICA Research, VIC)