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

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Postharvest Disease Summary 319
Alternaria alternata and species of Colletotrichum, Botryosphaeria and
Phoma (Hawthorne et al., 1982; Opgenorth, 1983; Pennycook, 1985;
Sommer et al., 1994).
A. Botrytis cinerea Pers. [perfect state: Botryotinia fuckeliana (de
Bary) Whetzel]
The gray mold rot caused by B, cinerea is the most serious disease of
kiwifruit in storage (Sommer et al., 1994). Botrytis conidia are capable of
surviving on the surface of kiwifruit, where they remain viable and
infectious throughout the growing season (Walter et al., 1999). Under
moist conditions invasion may take place via senescent floral parts at the
blossom end, after which the fungus remains quiescent for some time in
storage before resuming activity (Opgenorth, 1983; Sommer et al., 1983).
Botrytis may also penetrate the fruit through the cut stem or through
wounds in the skin (Sommer et al., 1983). Conidia on the leaves and
those accumulated on the hairy surface of kiwifruit are the major sources
of inoculum for infection of the picking wound at harvest or after it
(Pennycook and Manning, 1992).
Infection results in soft rot at the site of penetration, and it continues
to develop, although very slowly, at 0°C. During prolonged storage the
fungus can spread by contact from decayed to sound fruit, causing a
typical 'nesting' of gray mold rot. In addition to the direct losses caused
by B. cinerea, infected fruit produce ethylene in cold storage, which
accelerates softening of healthy fruits (Brook, 1991).
B. Other Pathogens
Species of Phoma, Colletotrichum and Botryosphaeria are capable of
colonizing dying flower parts and entering the young fruits on the tree.
However, they remain quiescent at the site of penetration until the fruit
ripens after harvest. Hence, the name 'ripe rot' frequently given to these
rots (Snowdon, 1992). Phomopsis actinidiae (perfect state: Diaporthe
actinidiae Sommer & Beraha) may initiate stem-end rots when the fruit
ripens (Hawthorne et al., 1982). Although the fungal development is
suppressed in cold storage, growth is resumed when the fruit is
transferred to shelf-life conditions. Decay can also be caused by several
species of Penicillium, which penetrate the fruit via injuries. Alternaria
species may grow on the fruit surface but are not considered primary
pathogens (Eckert and Ogawa, 1988).
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