Fumigation Defined
It is a process where a fumigant which is a chemical at a required temperature and pressure can exist in gaseous state in sufficient concentration which will be lethal to a given pest organism.
Why Fumigate?
Fumigation of cargo becomes very essential because there are possibilities of hidden infestation in the cargo, which is being exported. It can happen due to following factors.
- The infestation develops due to high moisture level in the cargo
- It depends on the place of storage prior to shipment.
- It happens during the time of transit due to previous cargo residues, which might exist in the container/ ship hold.
- Infestation also happens during transit from other cargoes which are migrated.
The infestation rapidly develops during the voyage period and when the cargo reaches port of discharge it is re-fumigated again at the cost of exporter/ buyer. It is always good to carry out fumigation prior to export to avoid huge fumigation and handling cost at the port of discharge.
Methyl Bromide Fumigation
Methyl Bromide is most widely used fumigant for Quarantine purposes. It is a preferred fumigant for most of the quarantine authorities around the world, because of its good penetrating ability, rapid action, high toxicity to a broad spectrum of insects and pests. It is frequently used for fumigating timber, agricultural products, empty containers, food stuffs, and other agricultural produce.
When fumigation is carried out with Methyl Bromide fumigant residue problems will not be there as aeration can be carried out easily. It is very effective in controlling all stages of insects from egg to the adult stage. Quarantine Authorities around the world have stipulated that methyl bromide fumigation has to be carried out for all the packing materials which are made out of Wood, Straw materials.
Fumigation Of Wooden Crates
Methyl Bromide fumigation should be carried out for packing wood crates, skids and other packing materials. Plant material such as straw, rice hulls and similar plant material used as packing material can carry exotic insect pest and diseases. The wooden crates have to be treated prior to shipment by carrying out fumigation with Methyl Bromide. The maximum thickness of the packing wood should not exceed 200 mm.
After completion of fumigation ISPM marking will be marked on the wooden crates for eg: IN 001 MB
Dosage And Exposure Period For Methyl Bromide
Methyl Bromide fumigation is carried out at the dosage between 32 gms per cubic meter to 80 gms per meter cube. The dosages vary as per the quarantine requirements of each country. The exposure period of Methyl Bromide fumigation is between 24 and 48 hours. This again depends upon the quarantine requirements.
Normally fumigations are carried out with Methyl Bromide for all cargoes containing wooden packing materials. Sometimes, the containers are moved for shipment before they are degassed. When this happens the degassing has to be carried out at the port of discharge by an approved fumigator.
The process will be opening of the doors completely and a fan has to be used to flush out the fumigant from the container. After the ppm levels reaches 0.1 ppm then it is safe for the unloading personnel to enter the container for de-stuffing the cargo.
Aluminium Phosphide Fumigation
Aluminium Phosphide is in the form of tablets and is packed in a flask. It is used worldwide for fumigation of raw and processed commodities including grains, tobacco, cocoa beans, nuts seeds, animal feeds, tea, coffee leaf, wheat flour, processed spices, and dried fruits. It can also be used for fumigating storage.
Dosage And Exposure Period For Aluminium Phoshohide
Aluminium Phophide fumigation is carried out at the dosage between 9 gms and 12 gms per Metric tone depending upon the buyers requirement. The exposure period of Aluminium Phosphide is 120 hours (5 day) after which aeration is carried out.
Heat Treatment
Heat treatment is carried out by storing the wooden pallets inside a closed chamber and Forced Hot Air is passed on through the wooden pallets inside the chamber. Blowers are placed inside the heating chamber for the circulation of hot air. Temperature monitors are placed at different levels inside the hot treatment chamber and the hot air temperature is monitored.
The hot air is generated with the help of a diesel burner firing it into a chamber and the hot air is collected from the chamber and passed on to the wooden storage section. The temperature is 560c is maintained for a period of 30 minutes after which the temperature is brought down slowly and the wooden pallets are removed from the chamber and HT mark is made.