The Australian Government Department of Agriculture, Water and the Environment (DAWE) imposes seasonal measures to prevent biosecurity incursions of brown marmorated stink bug (BMSB). For the wine industry, these measures include a mandatory fumigation and/or heat treatment of high risk imported products such as oak barrels, corks, glass bottles and closures. Other winemaking additives and products may also be subject to treatment or random inspections or if they are part of a consignment that contains target high risk goods.
Fumigation treatments
The two fumigation treatments announced by DAWE are methyl bromide or sulfuryl fluoride. These agents have been used as insecticides for more than 50 years. They are toxic to a wide variety of pests and have the ability to rapidly penetrate into materials and then dissipate after aeration, leaving minimal, if any, residue.
Fumigation of glass with methyl bromide and or sulfuryl fluoride
The fumigation of palletised glass occurs prior to its arrival in Australia. This means that fumigation occurs either in transit or prior to leaving the country of origin, after the glass has been palletised and shrink wrapped. The fumigation treatment process takes three days, and involves the piercing of the shrink-wrapped pallets to ensure the fumigant penetrates inside the wrapped bottles. The fumigation is then followed by two days of airing. The goods will not be released until this process has occurred and the correct paperwork has been completed.
What are the risks of fumigation with methyl bromide and/or sulfuryl fluoride?
When the AWRI helpdesk was approached with questions on any risks associated with the fumigation treatments, a review of the literature was conducted. The following key points were identified based on that literature review:
- methyl bromide (MB) and sulfuryl fluoride (SF) are very volatile, with low boiling points
- both MB and SF will dissipate quickly after fumigation
- glass is inert and therefore will not absorb or retain any residues that can be transferred into wine upon packaging
- if glass bottles contain moisture at the time of fumigation, it is possible for some MB and SF to dissolve in this water residue; however, the amounts would be very small
- any residues remaining in the water would evaporate or be removed with rinsing
- it is extremely unlikely for tribromoanaisole (TBA) taint to occur from fumigation with MB
- It is possible that MB and SF might adsorb onto the plastic wrapping; however, the impact of this is unknown
- There is also potential that winemaking additives and processing aids present in fumigated containers could adsorb methyl bromide or sulfuryl fluoride, and that it could take some time for the adsorbed fumigants to dissipate.
As an extra safety precaution, the AWRI recommends that all bottles treated with MB and SF be subject to water rinsing on the bottling line instead of just gas rinsing (which will only displace physical residues). Due to its low boiling point, it is not possible to measure SF. It is possible to measure MB but not at the low levels likely to be present. It is also not possible to reliably measure for residual bromide and fluoride ions.
Regarding barrels, the AWRI’s helpdesk has not encountered any issues in the past of taints resulting from fumigation of oak barrels. However, if an oak barrel has a high moisture content, there is a possibility it could contain residual bromide (from methyl bromide) or fluoride (from sulfuryl fluoride) ions after fumigation. Consequently, it is advisable for fumigated barrels to be filled with water that has had any chlorine removed for 48 hours after airing, to minimise any risk of residual bromide or fluoride ions.
Heat treatment
The third treatment option proposed by DAWE is for containers to be heat-treated at 50 degrees Celsius or higher for at least 20 minutes. Note that the DAWE website only lists offshore treatment providers, so it appears that heat treatment must be performed before departure from the country of origin. One possible issue arising from heat treatment is the drying out of oak barrels, which has potential to cause leakage.
What to do if a pest is found?
The AWRI advises grapegrowers and winemakers who transport or receive goods from overseas to be vigilant in checking for BMSB and other biosecurity risks. If any type of live pest is found while unpacking or moving goods, it must be reported immediately to the DAWE Hotline on 1800 798 636. If a live pest is found:
- Collect and contain a specimen.
- Re-seal any opened boxes, re-pack the container where possible, and shut the container doors.
- Do not move the container, especially to an outside area.
If growers or winemakers think they have seen BMSB (or any other exotic pest) in the vineyard or winery, they should phone the Exotic Plant Pest Hotline on 1800 084 881.