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

FREEDOM PALESTINE FREEDOM PALESTINE FREEDOM PALESTINE
268 Postharvest Diseases of Fruits and Vegetables
I. SUBTROPICAL AND TROPICAL FRUITS
This group of fruits comprises unrelated species, most of which are
chmacteric (pineapple being an exception). All the fruits of tropical and
subtropical origin are characterized by their perishability: the harvested
fruits have lost most of the intrinsic resistance characteristic of young
and immature fruits, are rich in nutrients, have high moisture contents
and are susceptible to attack by several pathogenic fungi (Eckert, 1990).
The storage life of tropical fruits is relatively short - generally a few
weeks under optimal conditions. The use of refrigeration to extend their
storage life is limited since these fruits are sensitive to chilling injury
and cannot be stored below their critical chilling range (Wang, 1990).
Sensitivity to cold storage varies with the fruit species or cultivar, and
also with the state of maturity. Because of their sensitivity to chilling
injury, bananas should be stored at 13-16°C, lemons, grapefruits or
mangoes at 10-15°C and papayas at 7-10°C. Under these conditions,
pathogens such as Colletotrichum gloeosporioides or C. musae will
continue to develop on mango or banana fruits, respectively, as will
Penicillium digitatum, P. italicum and Geotrichum candidum on various
sensitive cultivars of citrus fruits. In fact, postharvest decay losses of
tropical and subtropical fruits have been estimated to be up to 50%,
especially in developing countries where postharvest handling and
storage are not optimal (Eckert, 1990). However, the demand for tropical
fruits in the markets of non-producing countries continues to increase, as
indicated by the expansion of trade among widely separated countries,
although to reach some markets the fruits must undergo journeys long in
terms of distance and time (Burden, 1997).
CITRUS FRUITS
1. Wound Pathogens
Penicillium digitatum Sacc. (the green mold fungus) and
P. italicum. Wehmer (the blue mold fungus) are the main wound
pathogens of citrus fruits, causing the most common and the most
devastating postharvest diseases. They occur in all citrus growing
countries, worldwide and may attack the fruits in packinghouses, in
transit, in storage and in the market. The green mold, which is specific to
citrus fruit, is more prevalent than the blue rot, and may account for
most of the postharvest decay of citrus fruit in storage. The two fungi
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