Post harvest diseases fruits and vegetables - Xavier University ...

FREEDOM PALESTINE FREEDOM PALESTINE FREEDOM PALESTINE
Postharvest Disease Initiation 21
spore-bearing mycelium within the fruit core, without causing the
external rind to decay (Miller, P.M., 1959). Core rot of apples, that
results from infection through the sinus between the calyx and the core
cavity, may be attributed to various pathogens, including Aspergillus
niger and Fusarium spp. (Miller, P.M., 1959); Botrytis cinerea, Mucor
piriformis, Pleospora herbarum, Penicillium funiculosum and P.
expansum (Combrink et al., 1985; Spotts et al., 1988); Phomopsis mali
(Rosenberger and Burr, 1982) and Trichothecium roseum (Raina et al.,
1971).
3. PENETRATION DURING AND AFTER HARVEST
Penetration via Wounds
In contrast to pathogens that attack the fruit and vegetable in the
field, most of the storage pathogens are incapable of penetrating directly
through the cuticle or epidermis of the host, but require a wound or an
injury to facilitate their penetration. Therefore, the fungi and bacteria
that develop during storage are often called "wound pathogens". The
wound can vary in nature. Growth cracks present on harvested fruits
and vegetables are natural avenues of infection. The actual harvesting is
accompanied by mechanical injuries that enable the weak pathogens to
penetrate. Careless separation of the fruit or vegetable from the parent
plant might result in an injury liable to be attacked by the pathogen. The
extent of injury caused by mechanical harvesting is far greater than that
caused by a manual operation (Fuchs et al., 1984). Each scratch, incision,
blow or other mechanical injury inflicted on the fruit or vegetable during
each of the handling processes - harvesting, gathering, transporting,
sorting, packing and storing - might present adequate penetration points
for the storage pathogens. A likely penetration point is the stem-end
separation area, where damage often occurs during fruit picking. In this
regard, the separation area is no different from any other injury. It often
happens that simultaneously with the injury, a large amount of fungal
spores and bacterial cells arrive at the injured area, some of which will
use the injury site to penetrate and infect the host.
Penetration through wounds is characteristic of Penicillium
digitatum and Penicillium italicum conidia in citrus fruits. Yet it has
turned out that the depth of the injury, combined with the atmospheric
humidity conditions during storage, can determine the fate and extent
of the infection (Schiffmann-Nadel and Littauer, 1956; Kavanagh and
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