Onions, Shallots and Garlic - Crop Post-Harvest: Science and Technology - page 416

micro-organisms were applied to the onion rhizoplane at
transplanting in order to identify those most effective
against storage rots and the best time for application.
Trichoderma harzianum strain TM was effective in
reducing basal rot infection from 16% to 4%. When the
antagonists were applied to onion necks at top cutting, both
T. harzianum TM and Bacillus amyloliquefaciens strain
BL-3 completely suppressed neck rot in one test.

lait' of garlic, caused by Pseudomonas fluorescens , was
found in several European countries (Jacques et al . 2000).
Mites which attack garlic in storage include Aceria
tulipae . Courtin et al . (2000) studied its biology to identify
the environmental conditions which most favour the pest.
They found that a temperature of 25°C was ideal for rapid
multiplication. The mite's development was arrested by
low-temperature storage, but it was not completely killed.

Pests
Some pests can become a nuisance in onion stores. In
Egypt, a number of mites found on onions have been
shown to transmit Aspergillus spp. and other moulds
between onions or garlic in storage, either on the outside of
their bodies or via the digestive tract (Abdel-Sater & Eraky
2002). Stores which are not kept clean can also harbour
other pests such as beetles which can damage onion
bulbs; stores should also be well protected against rodents
and should be checked regularly for signs of the gnawing
damage to the structure which will allow them to enter
(Brice et al . 1997).

LONG-DISTANCE TRANSPORT BY SHIP
Onions are often transported in steel shipping containers:
for preference, these should be temperature controlled and
have the possibility of being ventilated with ambient or
recycled air en route , particularly if the journey will take
several weeks. Onions from Australia and New Zealand go
through several climatic zones before reaching Europe and
the use of 'fantainers' or refrigerated ('reefer') containers
is recommended to keep the onions in good condition.
Failure to take care of onions in transit can lead to expensive
losses, for example through condensation water falling on
the bulbs and staining the skins, or by the development of
severe surface moulds (usually Penicillium spp.). Delays in
tropical ports can be disastrous if the ventilators cannot be
kept running. On arrival at the destination port, the onions
will probably be damp skinned and should be unloaded and
dried out as rapidly as possible, so as to stop further water
losses. Once the skins have dried out to a safe moisture
content but are still flexible, the onions can be put over a
grader and packed for market into mesh bags. The poorer
quality external scales are usually lost at this stage so the
appearance of the bulbs improves when the brighter
underlying dry skins are revealed. Onions showing
signs of damage, staining, sprouting and so on make the
batch unsuitable for the higher-quality classes but the
lower grades may still have a value for processing where
surface-quality criteria are less important. The problem of
maintaining quality after shipping was studied by Dean
and Patil (1995) in the north-western United States in
connection with exports of sweet onions to Japan.

GARLIC PATHOGENS AND PESTS
IN STORAGE
A somewhat different collection of pests and diseases can
attack garlic: these include storage mites (Abdel-Sater &
Eraky 2002), which are less often a problem on onions, and
Penicillium spp. moulds which can attack individual cloves
and dry them out or reduce them to powder. Studies in
Poland found that garlic was infected by species such as
P. viridicatum and other Penicillium species. These species
were also found on the roots before harvest, as was
Fusarium oxysporum (Machowicz-Stefaniak et al . 1998a,
1998b). In Botucatu, Brazil, fungi present on or in garlic
bulbs were identified as Penicillium spp., Fusarium spp.,
Aspergillus spp. and Embellisia allii : various fungicides
were tested for efficacy against them (Soares & Kurozawa
1998, 1999). In Maharashtra, India, A. niger was the most
important pathogen found on garlic bought in local
markets (Guldekar et al . 1999), whereas in Khorasan, Iran,
F. oxysporum was the most damaging fungus (Mahmoody
1998). In Egypt, several other fungi were also found,
including A. niger , A. versicolor , P. chrysogenum , P. funic-
ulosum and several 'field fungi' and the three mites species
found were capable of moving these fungi from one plant
to another within the store (Abdel-Sater & Eraky 2002). In
Jiangsu, China, bacterial diseases caused by Erwinia ,
Bacillus spp ., and Rhodococcus spp. were identified on
garlic, as were the fungi P. chrysogenum , A. niger and
F.oxysporum (Ge & Xu 2001). A bacterial disease, 'café au

MARKETING ONIONS AND GARLIC
TO CONSUMERS
Plastic mesh sacks holding 12 to 25 kg are commonly used
to transport onions from packhouses to commercial outlets
(in the United States, 50 pound (22.7 kg) bags are com-
monly used). In less-developed countries, very large jute or
hessian sacks containing over 100 kg may be used for
onion transport (David & Moustier 1998): these are not
ideal since they can crush the onions and also allow people
to walk or lie on the bags when being transported by truck.