Caballero B. (ed.) Encyclopaedia of Food Science, Food Technology and Nutrition. Ten-Volume Set

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cultivated trees are common. The trees are also found

in the wild. The fruits are most pleasant and refresh-

ing; they are eaten fresh and can be processed into

juice, jams, and organic vinegar. The fruit is well

suited for cooking. The fruits are borne on long stalks

hanging down from branches and trunks. The edible

portion of the fruits is the segmented juicy translucent

pulp. Most rambai is sour but there are trees purport-

edly producing fruits that are less acid. The fruits are

seen in the markets during the season (June to August).

0008 There are usually two compartments in a fruit,

with two segments. In a ripe fruit, the segments are

enclosed in thin membrane. The juicy pulp adheres

firmly to the small flat seed.

0009 The rambai tree grows to a medium size (8–10 m)

however, some can reach up to 20 m height, spreading

with large green leaves 15–30 cm in length and

7.5–15 cm wide. The thin papery leaves are smooth

on the upper surface and darker green than the under-

surface. Flowering spikes arise from the trunk and

branches but rarely on smaller branchlets. The short

spikes grow as the flower buds mature and when the

light yellow flowers open, the spikes have already

extended and hang down. The strong sweet fragrance

of the flowers attracts tiny insects for pollination.

Young fruits are green and roundish with straight

tapering at the apex. Mature/ripe fruits have a mauve

color with less latex present (Figure 1). The rambai

tree is hardy and can tolerate a wide range of environ-

ments. Fruits are produced in abundance. It would be

useful to explore and look into greater use for the

fruits, particularly in downstream processing.

Baccaurea polyneura

(Jentik-jentik)

0010 Baccaurea polyneura is found only in peninsular Ma-

laysia and Sumatra. The trees are quite rarely culti-

vated and the fruits are sometimes seen in the market

in the northern states of Peninsular Malaysia when

in season (July to September). The fruit is an ovoid

capsule, 2.0–2.5 cm long, and orange to slightly

brown in color (Figure 2). They are juicy and have a

sweet-sour taste and are eaten fresh. An interesting

characteristic of the fruit is that it can be made to split

by flicking and appropriately is called jentik-jentik,

i.e., flick-flick.

Canarium odontophyllum

(Dabai,

Kembayau)

0011Dabai is a fruit that would seem to have potential as a

widespread food source in the tropics. The trees are

very heavy-bearing. The fruit is often white when

immature, turning black when it is ripe. The oblong

fruit, 35–50 25–30 mm, is ready for harvest when

fruits lose the white sheen covering the fruits. A good-

quality fruit has an oily yellow appearance when the

black outer skin is removed. The edible portion is

the mesocarp which is 2–3 mm thick and surrounds

the hard triangular seed. It is a good source of protein

and is usually softened in hot water before being

eaten with sugar or soy sauce. The sugar or soy

sauce enhances the richness of the fruit. By itself, the

fruit does not have much flavor but it is popular

throughout Sarawak during the season (around Oc-

tober to January). Dabai is also common in Brunei

Darussalam, and is found in most parts of the country

except in the swamps and coastal sand.

Dimorcarpus longan

ssp.

malesianus

var.

malesianus

0012Dimorcarpus longan ssp. malesianus var. malesianus

(mata kucing, isau, sau, kakus) trees are found all

over Indo-China and Malesia; the greatest variation

is found in Borneo. The fruits are globular to slightly

fig0001 Figure 1 (see color plate 74) Fruits of Baccaurea motleyana.

fig0002Figure 2 (see color plate 75) Fruits of Baccaurea polyneura.

2818 FRUITS OF TROPICAL CLIMATES/Lesser-known Fruits of Asia

oblong and smooth to warty. The fruit is drupaceous,

and is about 2 cm in diameter. Seeds are globular with

shining blackish-brown testa enveloped by a thin

translucent flesh. In Peninsular Malaysia, the most

common form of this taxon is the one with globose

smooth fruits which turn brown when ripe. It has a

very thin arilloid (flesh) and is hardly worth eating.

Superior forms are found in Sarawak, all with densely

thick warty fruits and thicker arilloids. The compos-

ition of the fruit is not very different from longan, but

carbohydrates and energy values are much lower,

whereas much higher figures are given for mineral

content.

Flacourtia rukam

(Rukam, Indian Prune)

0013 Flacourtia rukam is a small tree which is widely dis-

tributed but scattered, both cultivated and wild, all

over Malesia. The fruit is a round berry, 2–2.5 cm in

diameter, light green to pink or purplish-green to dark

red with whitish, juicy, acid pulp. There are four

to seven flat irregular-shaped seeds. The ripe fruit

(Figure 3) can be eaten raw; it is rubbed between the

palms of the hand because bruising the flesh elimin-

ates astringency. It is also served in fruit salad (rojak)

with a spicy sauce, pickled, or sweetened with sugar

to make jam or confectioneries. The young leaves are

eaten raw in side dishes. Immature fruit is used to

prepare traditional medicine against diarrhea and

dysentery. The wood is hard and used to make house-

hold utensils such as pestles and furniture.

Garcinia atroviridis

0014 Garcinia atroviridis (asam gelugor, som-maw won) is

native to Peninsular Malaysia and Myanmar. It is a

distinctive narrow tree growing to about 8–25 m in

height with drooping branches, twigs, and leaves.

Leaves are commonly about 14–26 cm long and

narrow with a pointed tip and upturned edges. They

are dark green and glossy, and new leaves are bright

pink; all of them droop in a limp way. The female

flowers have four cherry-red, slightly convex petals

surrounding a thick green ovary which is capped by a

dull red stigma. Fruits are solitary on the twig ends

and hang down with their weight. They are about

7–10 cm in diameter and fluted from top to bottom

with 12–16 deep grooves (Figure 4). The skin be-

tween the flutings is smooth and thin. The fruit is

green at first, ripening to a bright orange-yellow.

0015Ripe fruits are acid and astringent in taste. They are

sliced and sun-dried, and used in cooking. The young

leaves can be eaten fresh or also used in cooking.

Although the fruit is not eaten fresh, the narrow tree

with drooping branches is conspicuous and would

make a beautiful ornamental tree if planted along

roadsides.

Garcinia hombroniana

0016Garcinia hombroniana (manggis hutan, beruas)

resembles mangosteen. The tree forms a crown of

dark green foliage, some extending 10 m, with tiers

of extended branches. The fruit is round, about 5 cm

in diameter, like a small mangosteen, and pinkish

orange in color when ripe. Fruits are borne at the

terminal axil. Between the red fruit rind and the

seeds is a sour edible pulp.

0017The tree thrives on sandy and rocky soil. The hardi-

ness of the tree offers the opportunity for this species

to be used as rootstock for the more valuable mango-

steen. The tree can also be planted as a shade tree and

looks attractive as a roadside tree when planted in a

row. Perhaps in the near future, when more informa-

tion becomes available, the fruits, seeds, and rind may

yield exciting products.

fig0003 Figure 3 (see color plate 76) Fruits of Flacourtia rukam.

fig0004Figure 4 (see color plate 77) Fruits of Garcinia atroviridis.

FRUITS OF TROPICAL CLIMATES/Lesser-known Fruits of Asia 2819

Garcinia prainiana

0018 Garcinia prainiana (cerapu, mencupu, cerpu) is an-

other species that is closely related to mangosteen and

not less attractive compared to other known species.

It is a rather small tree found over a small area of

the Peninsular Malay, chiefly about the south end

of the main range and also in the state of Perak,

often in village orchards. The fruit is round with the

top and bottom a bit flattened, and is about 3 cm in

diameter. The rind is green, smooth, and shiny when

immature and turns into a very attractive color of

shiny orange when ripe.

Mangifera caesia

syn. Mangifera

kemanga

0019 Mangifera caesia (binjai, belunu, kemang) has nat-

ural distribution in Sumatra, Borneo, and Peninsular

Malaysia. They are rather rare in forests and found

more frequently in periodically inundated areas and

marshes. In cultivation, binjai has spread to Bali,

Peninsular Thailand and, rarely, to western Java. Bin-

jai grows into a huge tree exceeding 30 m with the

crown held high above the ground. Branches that

hold up the crown are dense. Leaves are 10–30 cm

long and 4–11 cm wide, green, and with prominent

mid-ribs and veins. At flowering, the crown is covered

in a mass of tiny purple, magenta, or pink flowers

held together in erect inflorescences.

0020 Mature fruits are 10–15 cm long and 6–8cm

wide, oblong, brownish or yellow in color. The

juicy, sweetish-sour binjai fruit can be eaten fresh

when ripe. Mature fruits weigh 0.5–1 kg. The flesh

is white, juicy, smooth and almost devoid of fiber.

The wani form, which is mainly found in Bali but

also in East Kalimantan, is much liked this way

and fetches a high price in local markets, as the fruit

is palatable, juicy, and sweet, almost fiberless, and

the strong smell is completely absent. It is excellent

for making creamy juices. Binjai is often used to

prepare a spice based on chillies (sambal). In some

areas, the flesh of ripe fruit is pickled and preserved

with salt in jars, to make sambal when there is

no fresh fruit. Binjai contains 74.1 mg vitamin C per

100 g edible part.

0021 Binjai has potential as an export fruit, however,

there is a need for greater research on the fruit.

Nephelium rambutan-ake

syn.

Nephelium

mutabile

0022 The Nephelium rambutan-ake (pulasan, kapulasan,

bulala, ngoh-khonsan) tree is similar to rambutan, if a

little smaller, and the leaves are narrower. Leaves have

two to five pairs of leaflets which are about 8–14 cm

long and 3–4 cm wide. Fruits are oblong, about

5–7cm by 4–6 cm. The skin is very dark red when

ripe and is covered with short, rather pointed knobs

which are thick and fleshy but not elongated, as in the

rambutan fruit. The flesh is transparent, whitish or

rather yellow and the flavor is very sweet. Pulasan is

native to the Malesian region and can be found in

Malaysia, Thailand, Indonesia, and the Philippines.

There are several different races grown, which pro-

duce varying qualities of fruit.

Syzygium malaccense

0023Syzygium malaccense (Malay apple, jambu bol,

jambu merah) originated in South-east Asia but is

more restricted to Java, Sumatra, and Peninsular

Malaysia. Current distribution ranges from India

through South-east Asia to the Pacific Islands. The

trees are cultivated in home gardens and along drive-

ways and paths. The tree is about 5–20 m high;

the bark is gray and almost corky, and leaves are

large, 15–35 cm long, and 7–17 cm wide and are

bunched at the twig ends. The base is widened

abruptly from leaf stalks which are short and very

thick. Flowers, 5 cm across, are very striking, for

they are deep pink or cerise, and are in almost stalk-

less bunches on the upper part of the trunk and

on bare mature wood behind the leaves (not at the

twig ends).

0024The fruit is a berry, ellipsoid, 5–8 cm in diameter,

usually red with pink or white streaks, or dark red or

purplish-yellow or yellow-white. There is one seed in

the fruit; this is 2.5–3.5 cm in diameter and brown.

There is a central hollow; the flesh is thick, rather dry

and scented, and quite pleasant to eat. Eighty percent

or more of the fruit is edible. It contains more than

90% water.

See also: Fruits of Tropical Climates: Commercial and

Dietary Importance; Fruits of the Sapindaceae; Fruits of

the Sapotaceae

Further Reading

Aman R (1999) Buah-Buahan Malaysia. Kuala Lumpur:

Dewan Bahasa dan Pustaka.

Tinggal S (1992) Brunei Darussalam Fruits in Colour.

Brunei Darussalam: Universiti Brunei Darussalam.

Verheij EWM and Coronel RE (eds) (1992) Plant Genetic

Resources of South-East Asia, no. 2. Edible Fruits and

Nuts. Bogor, Indonesia: PROSEA.

Yaacob O and Subhadrabandhu S (1995) The Production of

Economic Fruits in South-East Asia. Kuala Lumpur:

Oxford University Press.

2820 FRUITS OF TROPICAL CLIMATES/Lesser-known Fruits of Asia

FUMIGANTS

R Davis, Pest Management Consultants & Associates,

Savannah, GA, USA

Background

0001 In the approach to this discussion of fumigants, an

attempt is made to define a fumigant and its uses in

the preservation and protection of food, feed, seed,

and fiber. This is followed by a listing of common

chemicals used as fumigants and their formulations

and major characteristics. Finally, there is a discus-

sion of common applications in use today with a

listing of suggested readings and resource industries

to supplement the presentation.

0002 Most importantly, it must be stressed that anyone

planning to use a fumigant should secure the manu-

facturer’s label, application manual, and a Material

Safety Data Sheet (MSDS). These documents can

usually be secured from the distributor. After reading

these completely, all directions should be followed

carefully. Local and national government entities

may have additional requirements such as training

and licensing.

0003 A fumigant can be defined as a chemical that

will exist as a lethal gas at ambient temperatures

and pressures. As a gas, it will diffuse through

air and permeate soil and most products of the farm

and forest. This includes food and nonfoods (raw and

processed), as well as most packaging materials, with

the exception of metals. This permeation interferes

with the biological processes of organisms, producing

a lethal effect on most living organisms, both pest and

nonpests, including man and his domestic animals.

This definition excludes aerosols that are particulate

suspensions and are dispersed as smokes, fogs, or

mists into the space to be treated. Aerosols being

particulate in form lack the ability to penetrate the

commodity to be treated. Fumigants are rarely com-

mercially available as gases. Availability is usually as

cylinders of pressurized liquids that become gas as

they are released in normal atmospheric pressure.

Hydrogen phosphide (phosphine) is available in a

solid form, a metal phosphide, and requires exposure

to atmospheric moisture to activate the gas. When

safely and effectively used, fumigants are efficacious

and important pesticides for those involved in pro-

ducing, storing, transporting, and processing many

products from farms and forests.

0004 A major reason for the wide acceptance of fumi-

gants in the past has been their ease of application

and the availability of different application method-

ologies. Additional modifications of application

methods have usually been available to meet varying

climatic conditions and storage characteristics. How-

ever, in today’s approach to pest control, the use of

fumigants has been limited in the numbers of fumi-

gants available and in their widespread use. This

limitation is due to the adverse effect on our environ-

ment, particularly interaction with our food prod-

ucts, resulting in unacceptable residues and in the

use of methyl bromide with its adverse effect on our

earth’s protective atmospheric ozone layer. An ideal

fumigant should: (1) have a low cost per effective

fumigation; (2) be highly and acutely toxic to all

stages of the target pest, but not unduly hazardous

to man and his domestic animals; (3) be highly vola-

tile, with a good ability to penetrate, but not be

excessively sorbed on and in the commodity, its

container or package; (4) have adequate warning

properties for easy detection; (5) be noncorrosive,

nonflammable and nonexplosive under practical

conditions; (6) be of low molecular weight to aid in

diffusion and penetration; (7) possess a good storage

life; (8) be readily removed by aeration; (9) be non-

injurious to seed germination or field and nursery

stocks; (10) produce no quality changes in raw and

processed foods; and (11) be easy and safe to apply.

0005Within this area of pest control, fumigants are used

in several important areas: (1) in the treatment of

wood and wooden structures for infesting insects,

primarily termites and boring beetles; (2) in the pre-

planting treatment of soil for the control of weed

seeds, soil infesting nematodes, and insects attacking

tobacco, various vegetables and nursery stock; (3) in

the control of rodents in and around structures and in

orchards; (4) as a preventive treatment in a nation’s

quarantine activities; and (5) in the treatment of raw

and processed stored commodities. It is the use of

fumigants in areas 2 and 5 that we are principally

concerned with in this presentation.

0006Today, with our increased ability in chemical an-

alysis, we can now measure minute quantities of

pesticides, including fumigant gases and their residues

in the air, and on and in the treated commodity. As

most pesticides, including all fumigants, are highly

toxic to man and the environment, it is now very

important that these highly toxic chemicals be only

applied by trained and licensed technicians. Anyone

planning to use fumigants as a control should investi-

gate what government regulations are in place and

what needs to be observed. In the rare event that there

is no regulating authority at the location where the

FUMIGANTS 2821

fumigation is to be carried out, the manufacturer’s

directions accompanying the fumigant should be

carefully followed. In the USA, the certification of

pesticide applicators and registering of pesticides is

vested in the Environment Protection Agency (EPA)

and in individual States’ Environment Departments.

Physical, Chemical, and Biological

Characteristics

0007 The primary factors that will increase or decrease the

activity and distribution of fumigants are tempera-

ture, atmospheric moisture, application duration, fu-

migant formulation, dosage, application procedure,

storage structure or other fumigation containments,

pressure (vacuum), aeration, pest population charac-

teristics and habitat, commodity, and contamination

(e.g. dockage in grain).

0008 The safe and effective use of fumigants depends,

in large part, on knowledge of the fumigant’s primary

chemical and physical properties. Table 1 below lists

fumigants that are in common use, in limited use,

or, in some instances, banned from use in many

countries. In the USA, only methyl bromide, hydro-

gen phosphide (phosphine), and sulfuryl fluoride,

Vikane

, are in common use and are approved by

the US Environmental Protection Agency. In this pre-

sentation, only methyl bromide and hydrogen phos-

phide will be discussed. Currently, sulfuryl fluoride

has very limited approval for use on foodstuffs.

0009 The temperature and atmospheric moisture of the

environment and commodity to be treated are the two

most important variables in achieving efficacy in fu-

migation. It is important in a good fumigation for the

fumigant to come into equilibrium with the tempera-

ture of the commodity being treated. An increase in

temperature increases the molecular activity of the

fumigant, which facilitates the diffusion and penetra-

tion of the gas with decreasing sorption. The opposite

effect occurs as the temperature decreases. The bio-

logical activity of the pest organism will increase with

temperature changes that are within the temperature

range of the life processes of the organism. This in-

crease in activity results in a more rapid respiration

rate. The acceleration in respiration increases the

intake of the fumigant resulting in a quicker kill.

Temperature decreases result in a lower biological

activity and will lengthen the time of application.

Also, it may result in a fumigation failure if the pest

does not receive adequate exposure to the fumigant.

0010The moisture content of a commodity, such as

grain, generally increases the sorptive capacity of the

kernels, with a resulting loss of fumigant concentra-

tion. In general, an increase in fumigant dose or fumi-

gation duration can compensate for sorption and

penetration when grain moisture is high. Atmos-

pheric moisture is essential for the activation of phos-

phine from magnesium or aluminum phosphide. If

the atmospheric moisture is too low, insufficient

phosphine may be produced in the prescribed time

required for insect kill.

0011In the release of cylinder gases such as methyl

bromide and sulfuryl fluoride, moisture can result in

increased residues on the commodities treated. Also,

with the release of methyl bromide, it may be neces-

sary to heat the pressurized liquid, so when it expands

to a gas, it will not use the air’s ambient heat, resulting

in freezing the moisture that condenses on the nozzle.

If this freezing occurs, it may prevent the release of

the fumigant. When releasing sulfuryl fluoride, it is

necessary to ‘shoot’ the gas into a warm air stream

created by a fan. If this procedure is not used, the cold

gas may cause the condensation of the atmospheric

moisture and create a fog that will plate out on the

tbl0001 Table 1 Common fumigants and their essential properties

Chemicalname Molecular weight

Boiling point (



Specific gravity as a vapor (air ¼1)

Flammability

Acrylonitrile 53.06 77.0 1.83 3–17

Carbon disulfide 76.13 46.3 2.63 1.25–44.0

Carbon tetrachloride 153.84 77.0 5.30 Nonflammable

Chloropicrin 164.39 112.0 5.70 Nonflammable

Ethylene dibromide 187.88 164.4 6.48 Nonflammable

Ethylene dichloride 98.97 83.0 3.35 6–16

Ethylene oxide 44.05 10.7 1.52 3–80

Hydrogen cyanide 27.03 26.0 0.93 6–41

Methyl bromide 94.95 3.6 3.27 Nonflammable

Phosphine 34.04 87.4 1.20 1.79

Sulfuryl fluoride 102.6 55.2 2.88

Nonflammable

From Weast RC, Atle MJ and Berger WH (eds) (1984) Handbook of Chemistry and Physics, 65th edn. Boca Raton, FL: CRC Press.

Harein PK and Davis R (1992) Control of stored grain insects. In: Sauer DB (ed.) Storage of Cereal Grains and their Products, pp. 491–534. Minneapolis,

MN: American Association of Cereal Chemists.

Vikane Gas Fumigant – Structural Fumigation Manual (1998) Indianapolis, In: Dow AgroSciences.

2822 FUMIGANTS

walls of the enclosure or on the commodity being

treated.

Methyl Bromide

Soil Treatments

0012 Methyl bromide has been the fumigant of choice in

the preplanting treatment of soils, because of its effi-

cacy for a wide range of plant pests residing in the soil

including fungus, nematodes, insects, and weed seeds.

Additional advantages include its relatively low cost,

ease of application, and short duration needed for

effective control and ease of aeration. Preplanting

fumigations, for the purpose of discussion, can be

divided into two general approaches – area applica-

tion and raised bed and row applications.

0013 The soil preparation, regardless of the application

methods, is similar. The soil must be plowed or other-

wise tilled to a depth required for an effective treat-

ment. This depth is usually 15–20 cm. The soil must

be worked until it is free of clods or large lumps. Crop

residues should be burned or worked into the soil

after harvest to allow for decomposition. Soil mois-

ture should be sufficient for seed germination and

should be maintained for several days prior to treat-

ment for best results. Soil temperatures should be at

15–27



C at a depth of 15 cm. Fumigations should not

be attempted if air temperatures are below 10



0014 Area applications Area applications should be

accomplished with a chisel-type applicator with a

spacing of not more than 30 cm between chisels. The

fumigant should be injected to a depth of 15–20 cm.

The soil should be covered immediately with polyethyl-

ene film by simultaneous film laying equipment. If a

soil compactor is used, the soil should be covered with

film or other suitable cover within 20 min. Recom-

mended applicator rates vary between 200 and

275 kg Ha

1

, depending upon the soil texture. Very

heavy soils may require greater dosages; in every in-

stance, the fumigant manufacturer’srecommendation

must be adhered to. Exposure times are usually 24–

48 h with a 72-h aeration; however, this aeration period

will vary with the crop to be planted. The aeration

period will need to be at least 5–7 days if the treated

area is to be used for transplanted seedlings.

0015 Raised bed and row applications These are modifi-

cations of the area application treatment. In row

applications, the polyethylene film is usually in rolls

90–130 cm wide and 305 m long. Alleyways are left

between the beds to allow for working the crop.

Application of the fumigant is as described above

for the area treatment.

0016The raised bed applications are used in small fields

or in greenhouses where table beds are used. Soil

preparation is the same as in the area application.

To prepare a raised bed, the area around the bed is

trenched with the soil thrown to the outside of the bed

so it can be used to bury the edges of the tarpaulin.

The tarpaulin or polyethylene film will need to be

raised and held off the soil to provide a space for the

fumigant to evaporate and distribute. This can be

achieved by using burlap bags stuffed with paper or

straw, flower pots, landscape timbers, etc. On green-

house tables, tape or glue can be used to hold and seal

the tarpaulin.

0017The introduction of the fumigant is through poly-

ethylene tubing anchored under the tarpaulin to an

evaporation pan. One pan should be of the appropri-

ate size to accept the required amount of fumigant

and should be of plastic or metal (do not use alumi-

num). In the absence of oxygen, liquid methyl brom-

ide reacts with aluminum to form methyl aluminum

bromide, which ignites spontaneously in the presence

of oxygen. The fumigant is introduced through the

tubes into the pans. Do not remove the pans or tubes

until aeration is complete. The fumigant may be va-

porized before introduction by means of a commer-

cial heat exchanger or by using a coil of copper tubing

immersed in a vat of hot water.

0018Other soil fumigants that have been used or are

currently available include – chloropicrin, dazomet,

dibromochloropropane (DBCP), dichloropropene,

and metam-sodium.

Space Treatments

0019Currently, only two fumigants are approved in the

USA and used to treat food, feed, and seed and

their processed intermediate and end products.

These fumigants are methyl bromide and phosphine

(hydrogen phosphide). Sulfuryl fluoride is the only

other common fumigant used in the USA where it is

the fumigant of choice for the control of termites.

Sulfuryl fluoride is a proprietary product of Dow

Chemical Company and is registered and sold as

Vikane

. It is not very effective for the control of

insect eggs and therefore is not believed to have

much promise for general use in chambers or other

types of structures. Vikane

may have some promise

for greater use in insect control. It is an excellent

fumigant for the control of the active stages of

insects. Termites, when they hatch, need to be fed

by the active stages of the species to transfer the

digestive fauna to the new generation. If no active

stages are available, it results in the death of

the colony. Currently, Vikane

is being investigated

for possible use in a broader range of pest-control

problems.

FUMIGANTS 2823

0020 Methyl bromide has both advantages and disad-

vantages as a fumigant. Recently, a major disadvan-

tage has come to light. This is that the bromide ion

has been determined to be a destroyer of our protect-

ive ozone layer. Other disadvantages are that it pro-

duces both inorganic and organic residues that often

exceed acceptable levels. In its application, its great

weight produces pools or puddles in the low parts of

chambers and other types of structures. This may

create hazardous situations that require special atten-

tion during exposure and aeration. When methyl

bromide is used, it is essential that the following

items are removed before the fumigant is introduced:

(1) all exposed food, feed and medicines; (2) seeds,

bulbs, and living plants unless being treated; (3) all

pets (including fish); (4) furs; (5) horsehair products;

(6) natural rubber goods; (7) photographic films and

blueprints; (8) automobiles; (9) cinder blocks; and

(10) all articles containing sulfur. It is also essential

to extinguish all flames such as pilot lights, turn off

electric heating elements, open all interior doors and

openings to attics and crawl spaces, and open all

drawers and cabinet doors when treating structures.

0021 The advantages are numerous but not of sufficient

importance to overcome all the disadvantages.

Methyl bromide is an excellent fumigant for quaran-

tine purposes. It has a low phytotoxicity and there-

fore can be used to control pests on live plants. It is a

relatively quick fumigant, very quick if used in

vacuum chambers, and is effective in the control

of most living organisms. It also follows a regime of

concentration times time (C T) for the control of

insects under a range of temperatures. This allows the

fumigator to vary either the fumigant dose or the

application duration to affect the desired control.

This fumigant behavior is particularly important in

the control of quarantine species. There is also a great

volume of C T data currently available on a multi-

tude of quarantine organisms.

0022 Chamber (vault) fumigations In these fumigations,

the material to be treated is loaded into the vault not

exceeding 75% of the available space. All the exhaust

ports are closed, circulating fans are turned on, and

doors are closed. The fumigant is introduced from

outside into the chamber above the material(s) to be

treated or into a shallow pan in front of a fan to allow

for complete vaporization and distribution.

0023 The exhaust ports should be opened, exhaust fans

turned on for aeration at the end of the exposure

period, inlet ports opened and/or the door opened

slightly to allow for fresh air to wash the fumigant

out of the chamber. It may be advisable to close the

chamber after a period of aeration and allow the load

to further degas. Then, further aeration should be

carried out until it is determined to be safe to remove

the material(s) and distribute. In the USA, it is safe to

enter the chamber and handle the products when the

gas level is 19 mg m

3

or less.

0024Vacuum chamber fumigations After the materials

to be fumigated have been placed in the steel vacuum

chamber, a vacuum is drawn to a level of 100–

380 mmHg depending on the product to be treated.

The methyl bromide is released into the chamber,

usually through a heat exchanger, to insure vaporiza-

tion. After completion of the required exposure, the

vacuum is released and the chamber air exchanged at

least twice using 380 mmHg per exchange. Released

air should be 19 mg m

3

or less to unload the

chamber safely.

0025Railcar, truck, van, and container fumigations In

the fumigation of these vehicles, two points must be

observed. First, they must not be moved while under

fumigation. Movement may reduce air pressure on

the outside of the vehicle and suck the fumigant out

of the vehicle or break the sealing and reduce the

available fumigant for the control of the pests. It

may also cause a possible hazardous situation.

Second, these vehicles are not manufactured to be

used as fumigation chambers. Many are constructed

using rivets that cannot be assumed to be airtight,

or have wooden floors that have cracks between

the boards. Containers (ship-truck type) often have

wooden floors and large rear doors. Both are very

difficult to seal. These containers are also used for

air shipments. This use requires that the containers

have pressure vents for the equalization of the atmos-

pheric pressure inside the container as it is moved

between different altitudes. If there is any doubt as

to whether or not the vehicle is sealable, it should be

rejected as not being acceptable for fumigation.

Aeration of these vehicle containers should be to

19 mg m

3

or less before unloading.

0026Tarpaulin fumigations The material(s) to be fumi-

gated should be stacked on an airtight surface and

covered with a tarpaulin that is of sufficient size to

provide a gas distribution dome and also allow for

sealing the tarpaulin to the floor. The methyl bromide

should be released from outside the stack and into

shallow pans in the distribution dome, one pan for

each 28 m

0027Aeration should proceed as follows: if fumigation

is being conducted inside a closed structure, all doors

and windows should be opened to provide cross-

ventilation. The tarpaulin should be opened on one

end to allow the stack to aerate for at least 30–60 min

before removing the tarpaulin completely. Again, it is

2824 FUMIGANTS

important to monitor the vicinity to insure that

the fumigant concentration is 19 mg m

3

or less,

and the material(s) fumigated is safe to handle and

distribute. If the fumigation is conducted outside a

structure, the aeration should be conducted in steps as

above with monitoring of the immediate surrounding

vicinity for safety.

Fumigation of Structures

Outside Release of Fumigant

0028 This type of fumigation is somewhat limited in use.

With very large buildings and multistory buildings,

this method is not usually practical. When treating

the building as well as its contents, exterior sealing

of the building is usually required. For treating the

contents of the building, interior sealing or tarping

the contents will be required. Release of the fumigant

should be into shallow evaporating pans (one pan per

35.3 m

) in front of a fan or through a heat exchanger

into the building in front of fans for gas distribution.

The building should be locked and guards placed

outside if required or needed. Opening the doors

and starting the exhaust fans followed by opening

all the doors and windows to complete aeration

should achieve aeration. Entrance must be prohibited

until gas levels are at or below 19 mg m

3

Inside Release of Fumigant

0029 This is the more commonly used method of fumigat-

ing buildings with methyl bromide. In this applica-

tion, cylinders of gas are placed in the upright

position throughout the structure after the building

has been sealed. The cylinders are arranged so that, as

the cylinders are opened, the fumigators can walk

away from the released gas as they leave the building.

As methyl bromide is a heavy gas, more gas is usually

released on the upper floors of multistoried buildings.

It is recommended that fans be placed throughout the

building (one fan per 1400 m

) to assure distribution.

The entire operation of releasing the fumigant should

be completed in less than 30 min. The fumigators,

when releasing the gas, should work from a map

and in pairs for safety.

In-transit Shipboard Fumigation

0030 Methyl bromide is rarely, if ever, used for this type of

fumigation. The weight of the gas makes it difficult to

remove it from a ship’s hold, and the duration of the

treatment is the duration of the voyage, which can

be up to a month or more. During long voyages, the

methyl bromide is usually sorbed in the commodity,

particularly if it is grain in bulk. This can result in

unacceptable residues. The methodology of this

fumigation treatment has been largely limited to

bulk grain fumigation with hydrogen phosphide

(phosphine).

Hydrogen Phosphide (Phosphine)

0031Phosphine is usually produced from either aluminum

phosphide or magnesium phosphide in the presence

of atmospheric moisture. This chemical reaction is as

follows: metallic phosphide þ3H

O > metallic (OH)

þ phosphine gas. The manufacturer, in order to pre-

vent fire and/or explosion, has appropriately buffered

this reaction. After the gas has been evolved, the

residue remaining consists of the metallic hydroxide

that appears as a gray–white powder. A small amount

of undecomposed metallic phosphide may be present

in this powder, and the phosphide must be deacti-

vated, as directed by the manufacturer before it can

be disposed of. Care needs to be taken that this dust is

not inhaled.

0032Phosphine is available in several formulations

that facilitate the ease of using this fumigant. Not all

the manufacturers or distributors usually have all the

brands or formulations available. The various formu-

lations are as follows:

0033Rounded tablets of 3 g each which produce 1 g of

phosphine and usually are available in resealable

aluminum flasks of 100 and 500.

0034Pellets of 0.6 g each, which produce 0.2 g of phos-

phine and are available in resealable aluminum

flasks of 1660.

0035Sachets, bags, or blister packs of varying shapes

weighting 34 g, which produce 11 g of phosphine.

This product comes in steel cans, and the sachets,

bags, and blister packs are often in chains or

fastened together in some manner for ease of

application.

0036Phosphine in a mixture of 2 parts of phosphine in

98 parts of carbon dioxide. This mixture is avail-

able by employing a firm that has a phosphine

generator or by purchase of the premix in cylin-

ders. The gas is applied through a closed system or

released in a sealed structure.

Not all formulations are available or approved for use

everywhere

0037Phosphine is very toxic to all forms of animal life,

and even any exposure to man in very small amounts

must be avoided. The threshold limit value has been

set at 0.42 mg m

3

by most countries for the 8-h

workday. Phosphine produces a toxic effect on the

organism’s utilization of oxygen. It is known that in

insects, this effect is potentiated by the presence of

additional carbon dioxide. In the evolving of the

gas from the metallic phosphide, the most important

FUMIGANTS 2825

variables are the ambient temperature and atmos-

pheric moisture. An increase in either or both will

increase the rate of gas production. All directions

provided by the manufacturer – label, material safety

data sheet, and application manual – must be

followed carefully.

0038 Phosphine as a fumigant has a number of advan-

tages in addition to its toxicity. The small amount of

phosphide necessary to generate the gas required

makes the fumigant very portable. Its low molecular

weight, which is close to that of air, allows the gas to

distribute well and rapidly penetrate packaged com-

modities such as processed foods and kernels of grain

and seeds of legumes. Although very toxic, its mode

of action on animal respiration is rather slow and

allows for the use of low concentrations, particularly

when there is sufficient time for long exposures.

0039 There are also several disadvantages in the use of

phosphine. It is corrosive to metals such as copper,

copper alloys, and precious metals such as silver and

gold. This can result in damage to electronics and

electrical office and other equipment. It is important

to protect such metals and equipment or remove them

from the area being fumigated. Areas with low

oxygen levels or where insect respiration is low from

low temperatures may result in poor or incomplete

control. Phosphine can be spontaneously explosive

when it exceeds a concentration of 1.79% of the

volume of the atmosphere. This prohibits its use in

vacuum chambers or in other situations where the

atmosphere may be reduced in volume. Phosphine

has not been used successfully in the treatment of

soil organisms, as many of them use very little

oxygen. It also has been difficult to confine the gas

to the soil area long enough to be treated because of

the inability to seal the area adequately and because

of the great activity of the gas. Although it has been

recommended for the fumigation of wood and wood

products, it has not been used extensively, because of

site safety, difficulty in securing a satisfactory seal,

and achieving the required penetration during the

exposure duration.

0040 However, the use of phosphine as a fumigant has

been used successfully in the control of insects

attacking a wide range of dried food commodities

both raw and processed. Phosphine has been used

very extensively for the treatment of grain and grain

products in both static and in-transit conditions. It

has also been used successfully for treating many

nonfood commodities. With the exceptions noted

above, phosphine can be used in most situations

where methyl bromide has been used or is currently

being used.

0041In every use of a fumigant, it is incumbent upon the

fumigator to read carefully and follow the manufac-

turer’s instructions. In countries with a pesticide regu-

latory authority, the fumigator should secure all the

information made available. In most countries with

regulatory authority, their instructions on the use of

pesticides have the effect of law.

See also: Cereals: Bulk Storage of Grain; Handling of

Grain for Storage; Cleaning Procedures in the Factory:

Types of Disinfectant; Insect Pests: Insects and Related

Pests; Problems Caused by Insects and Mites; Pesticides

and Herbicides: Types of Pesticide