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

FREEDOM PALESTINE FREEDOM PALESTINE FREEDOM PALESTINE
270 Postharvest Diseases of Fruits and Vegetables
fruits, causing 'nesting'. The green mold typically infects adjacent fruits
that have been injured (Barmore and Brown, 1982). The dusting of sound
fruit with Penicillium spores from decayed fruit, termed soilage, is often
of greater economic importance in retail cartons than is the decayed fruit
(Stange and Eckert, 1994).
Penicillium digitatum is capable of producing ethylene during its
development (Biale, 1940; Ilag and Curtis, 1968). The production of
ethylene, which is considered to be the ripening hormone, increases fruit
respiration (Achilea et al., 1985a; Biale and Shepherd, 1941), hastens
peel coloring and accelerates button senescence (hence leading to the
initiation of stem-end rotting). By producing and releasing ethylene,
P. digitatum reduces the storage life of healthy fruits in the same
container or sometimes even in the same room.
Geotrichum candidum Link ex Pers., the sour rot fungus, has been
reported from most citrus growing areas. The disease is usually of less
importance than the green mold and blue mold decays or the stem-end
rots. It is, however, particularly important after prolonged wet seasons
when heavy losses have been recorded. Furthermore, the importance of
sour rot may generally be underestimated because initial infections are
easily overgrown by other molds (Smoot et al., 1983).
Sour rot is primarily a disease in storage and in transit, although
infection may also occur on the tree. The spores (oidia), which are
thin-walled cells derived from the fragmentation of fungal hyphae, are
soil inhabitants being splashed during irrigation or rain to low hanging
fruits or contaminating the fruit by soil contact. Infection may initiate
preharvest at injuries caused by insects or via mechanical wounds
sustained during harvesting and packinghouse handling (Laville, 1974).
It is found most often on lemons, limes and grapefruits, which are often
stored for extended periods, but they may infect other citrus fruits as
well. Ripe fruit is more susceptible to the pathogen than green and
immature fruit (Baudoin and Eckert, 1985).
Early symptoms are similar to those of the green and blue mold
decay, being a water-soaked spot that enlarges along with or following
the growth of the fungus within the fruit tissues. At a later stage, a thin
water-soaked, off-white mycelium is developed on the affected area.
When a total decomposition of the fruit tissues occurs, a sporecontaining
juice leaks from the rotten fruit and can infect healthy
adjacent fruits.
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