Fumigation Tour

Southern Fumigation Services

BY SCARLET ROXBY VALUE CHAIN FACILITATOR, STONEFRUIT

On October 20, WA Stonefruit held a tour of the methyl bromide (MB) facilities at Southern Fumigation Services in Cockburn Central. Fourteen guests joined the two Adrians and Kylie to understand the inner workings of the fumigation process for produce coming from the Perth Markets.

The tour provided an understanding of MB requirements, variability and longevity of produce being fumigated, and gave growers peace of mind that Adrian and Adrian handled the produce professionally to provide customers with quality produce. The following provides notes from the discussion and tour.

Here are a few notes from the discussion and tour.

Fumigation process

Successful MB fumigation is dependent on an ideal combination of dosage rate, treatment time and treatment temperature. If one of these factors is incorrect then fumigation is not effective. (Successful fumigation = dosage rate x treatment time x treatment temperature). Produce must be greater than 10°C as a minimum and less than 32°C as a maximum, with the ideal range between 17°C – 20.9°C (see Table 1). At lower temperatures, the respiration of insects is reduced, therefore uptake of fumigant by insects is lower. Below 10°C insects are in a dormant state with limited respiration and movement. When produce arrives for treatment, the temperature of random pallets is measured with dosage rate being worked out based on the lowest temperature measured. Produce is brought up to 17°C in the fumigation room with a fan circulating air evenly. Pallets are spread out to assist air/ fumigant flow. MB concentration is monitored, recorded, and checked throughout the treatment, using three sensors equally distributed across the fumigation room. The fumigation process takes two hours, with an additional hour to vent MB gas before the room can be opened. The MB concentration reading is recorded manually 30 minutes after the MB release and 1 hour before the end of fumigation process, after which the gas is vented from the room.

MB must be below 5 parts per million (ppm) in the fumigation room before produce can be safely removed. If fumigation is occurring at night, the room can be scheduled to be a cool room on completion of fumigation. Most pallets have a same day turnaround time for fumigation, dependent on the time the produce is received, as fumigated produce will not be released until authority to do so is received from Quarantine WA (QWA). Southern Fumigation Services have the capacity to fumigate 45 pallets a day.

TABLE 1. FUMIGATION RATES FOR 2HR PERIOD.

Temperature (°C) 21+ 17–21 10–17 Rate of methyl bromide (g/m3) 32 40^

54

^ Best results

Methyl bromide is a controlled substance.

f TOUR group listening to Adrian and Adrian (left in yellow and orange) as they talk about the fumigation process.

f METHYL bromide signage.

Quarantine WA (QWA) & Quarantine Direction Notice (QDN)

Produce trucks coming into WA go to the transport company depots at Market City. Quarantine WA (QWA) then inspects the produce to determine if it is acceptable or if fumigation is required. This depends upon the product, protocols in place and what quarantine treatment has occurred prior to entry in WA.

If required, a Quarantine Direction Notice (QDN) is issued, for a fumigator to treat appropriately. The details on the notice must match the details of produce on the pallets, called a Quarantine ID (QID), including number of pallets/boxes, product, place of origin and destination. The quarantined produce is taken for fumigation and cannot be released without approval from QWA who provide a quarantine release notice. If the fumigation process is completed, and no release notice has been received, the fumigator must hold the produce until notice is received. If a QDN specifies that fumigation must occur before a set time and date and fumigation does not occur by this date/time, then a new QWA inspection is required.

Insect eggs are difficult to fumigate while larvae/pupae are killed easily. Risk of insects escaping from the fumigation facility (i.e., outside treatment room) is low because produce is cold (therefore insects are not moving). Southern Fumigation Services are currently investigating with DPIRD if it is feasible to do a low dose fumigation treatment for longer (e.g., 18g/m3 @ 18°C for 5 hours), however any change to protocol is dependent upon agreement between markets and Traceability is important and starts at the packshed. other States. Getting export markets and each state to agree to make changes to fumigation process/requirements is a difficult process. Areas of improvement

Methyl bromide characteristics

MB has no colour, taste or odour and dissipates quickly in air. The gaps between pallets allow the MB to penetrate through polystyrene, plastic etc, even when produce is in packaging. Like many pests, MB enters the produce via the stem area. Samples of produce are tested at markets to check the safety of MB treated produce for consumption. The dosage rate also accounts for the MB maximum residue limit (MRL) allowed in produce. MB is a controlled substance manufactured in India and imported through one company into South Australia. It is then sent to a depot in Perth for purchase by West Australian fumigators. MB is harmful to the ozone layer, with its only approved use in fumigation to limit the release of MB into the atmosphere. Records are kept showing the total amount released per year.

Traceability is important and starts at the pack shed. Traceability is tracked through the QDN for each pallet. Each pallet may contain a mix of produce from multiple growers; thus, traceability cannot always be narrowed down to a specific grower. What was in the fumigation chamber at same time is known due to QDN information. If traceability were to start at the individual grower level, determining the source of pest outbreaks could be quicker. However, any changes in traceability would need to be approved across all states before implementation. Despite MB being the best fumigation tool in many instances, the process can cause variable damage depending on the product. Heating fresh produce up to 17°C – 20.9°C is a problem as it reduces shelf life. Ideally, produce could be treated at picked temperature rather than heating up produce which has come out of a cool room or refrigerated truck. Upon removal from fumigation chamber, damage is sometimes noticeable, e.g., fruit burn when there is moisture / condensation on the fruit. Fans and airflow help to dry condensation from fruit but this can be less effective if produce is packed in plastic containers.

Fumigation facility feasibility

With recent outbreaks of Queensland Fruit Fly there has been thought about setting up fumigation facilities in growing regions to help mitigate the effects of an outbreak. Things to consider would include: • WA Department of Health need to approve a facility. Urban sprawl into the growing regions could make this difficult. • Continual throughput is important for the financial viability of a fumigation business. • If a pest outbreak were to occur and the fumigation facility was located within the Quarantine Zone, it would not be permitted to operate. A mobile facility could alleviate this risk, though approvals would still be necessary, and any movement of the facility would probably require additional approvals. Finally, we would like to thank Kylie, Adrian and Adrian at Southern Fumigation Services for hosting the tour of their facilities and thank you to Rachel Lancaster (Horticulture Biosecurity Liaison Officer) for providing detailed notes.

This event was held to help stone fruit growers gain a better understanding of the fumigation process and how it is implemented to help reduce the risk of biosecurity outbreaks in WA. ●

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