Treatment of rail cars
Rail cars are very difficult to seal and when moving, fumigant will be drawn out by wind action. It is recommended that rail cars are fumigated only if they can be well sealed, for example, lined with polythene sheeting, and can be held stationary for the duration of a treatment.
Pest management of insects
Fumigating small quantities of commodity
Small quantities of commodity may be fumigated conveniently with phosphine. The commodity can be placed in small containers such as empty oil drums or dustbins, provided they are sound, uncorroded and can be properly sealed. Commodities can also be fumigated in sacks made from plastic film, or in woven sacks fitted with liners of plastic film.
Phosphine applied as tablets is the most effective and simple method of fumigation for small quantities of produce. The tablet or pellet is placed in a paper envelope, which is then pushed down into the commodity before sealing the container. If the container has a well fitting lid, it may be sealed with adhesive tape. Containers without lids can be sealed by placing a plastic sheet over the top and securing this tightly with tape.
A major problem with fumigating small quantities of commodity is that of obtaining appropriately small quantities of phosphine-generating formulation. The normal packages of tablets (20 or 30 tablets per tube) are too large to be used at once and cannot safely be re-sealed. Some manufacturers are marketing sealed packs of three or five tablets, while some tablets can be obtained in resealable flasks. Recently, sachets equivalent to 3 g phosphine have become available.
Ship and barge fumigations
Commodity fumigation on ships is a hazardous operation that is difficult to do successfully. Fumigation has to be done in compliance with the ship’s flag regulations and those applicable at the port of call or of destination. The Recommendations on the Safe Use of Pesticides in Ships issued by the International Maritime Organization (IMO) provide a useful framework and are incorporated into many national regulations, making them mandatory in most instances.
On-board fumigation must be supervised by a qualified fumigator who selects the treatment, determines which spaces of the ship, if any, are safe for occupancy during fumigation, and manages the process. The responsibility for the treatment lies with the fumigator except where fumigation will be conducted in-transit, in which case it rests with the ship’s master.
Not all ships can be considered for in-transit fumigation as not all ship designs can guarantee a safe confinement of the gas to the space to be fumigated. Bulk carrier and tanker-type ships are generally deemed to be the most suitable for in-transit fumigation, tween-deckers being less suitable. In any case, cargo holds should be tested for gas-tightness and a fumigation protocol should be approved by the ship’s master and the relevant port authorities before in-transit fumigation can be considered.
Another significant problem with fumigation is ensuring the adequate distribution of fumigant throughout the holds, and subsequently its complete removal from the ship.
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Due to the considerable depth of grain in some of the larger vessels, some form of gas recirculation system may be required. If such systems are not used, then fumigation treatments will not be effective and may be regarded as only cosmetic.
Depending on the depth of the grain, a variety of methods of applying phosphine are available. These are of two basic types. The phosphide preparation may be confined to an easily accessible location and the gas that is generated may then be circulated and recirculated by a fan. Alternatively, the preparation may be inserted into many locations at various depths in grain so that the gas will be distributed when it is generated. Failure to distribute the fumigant sufficiently throughout the cargo will reduce the efficacy of the treatment and, where phosphide tablets or pellets are used, could lead to the occurrence of visible powdery residues in or on the cargo.
These residues could present problems for phytosanitary inspection and acceptance by the consignee.
In-transit ship fumigations should only be undertaken where it is expected that the duration of the voyage will be sufficient for the total release of the fumigant.
Otherwise the ship might dock with undecomposed fumigant preparations present in the cargo. This outcome would be more likely to occur when cargoes such as grain are shipped at lower than normal moisture content. The result would be a failed fumigation and a serious hazard to health for anyone exposed to, or working with, the cargo. The IMO issued a circular in 2003 advising that ships carrying bulk cargoes under fumigation should notify the appropriate authorities prior to arrival and ensure that the ship’s hold and its cargo are gas-free upon berthing.
Barges of sound construction may be fumigated using the same technique of application for bag stacks. Hatches should be sealed during the course of the fumigation.
Fumigation of shipping containers
With the general increase in the use of shipping containers, this type of treatment is now becoming more common. In some situations, containers fumigated with phosphine may be loaded onto ships without opening; the ventilator seals being removed during the voyage. Containers ‘under gas’ are always carried on deck. Care is needed to ensure that fumigated containers are properly labelled.
Some containers have wooden floors which are not gas-tight, although they can be sealed. Due to their very nature, even well designed containers will become damaged when they are handled, so all containers should be tested for gas-tightness prior to fumigation. Options include pressure testing, smoke tests, and the Contestor (an automated system for pressure testing containers).
Pest management of insects