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

FREEDOM PALESTINE FREEDOM PALESTINE FREEDOM PALESTINE
308 Postharvest Diseases of Fruits and Vegetables
storage the fungus produces a coarse, erect, white mycehum that gives
rise to globular black sporangia with new sporangiospores.
G. Alternaria alternata (Fr.) Keissler
Alternaria rot is common mainly in plums and cherries. The fungus
survives on dead material in the orchard and its spores are disseminated
in the air. Infection is usually associated with injury that occurs during
harvesting and handling. In cherries, fungal penetration can take place
through cracking or splitting of the skin while the fruit is still on the tree
(Snowdon, 1990). In apricots, the fungus can penetrate the sound fruit
via stomata (Larsen et al., 1980).
Lesions are firm, slightly sunken, and bear a dense mat of olive-green
or dark conidia.
H. Cladosporium herbarum (Pers.) Link
Cladosporium survives on dead plant material in the soil and produces
an abundance of conidia, which are disseminated in the air, and
constitute the most common component of the air spora (Gregory, 1973;
Barkai-Golan et al., 1977b). Cladosporium herbarum is a weak pathogen
infecting fruit that has been damaged by rain or rough handling. Plums
that have been shaken from the tree and collected from the ground
exhibited a particularly high incidence of infection (Michaelides et al.,
1987).
Lesions are limited in area and covered with a velvety mat of dark
green spores. Thanks to its low minimal growth temperature of -4°C
(Sommer, 1985), Cladosporium can grow and infect the fruit even at cold
storage temperatures.
Control Measures
Postharvest disease control of stone fruit pathogens consists of an
integrated combination of pre- and postharvest fungicide applications,
sanitation practices, cold storage, modified atmosphere storage and
biological control techniques. Chilling the fruit, which is the most
commonly used method, both slows ripening and inhibits the growth of
most decay pathogens (Eckert and Ogawa, 1988).
To control infection by wound pathogens, such as B, cinerea,
P. expansum, A alternata, R, stolonifer and M piriformis, control
measures should include the prevention of mechanical damage during
harvesting and handling, and application of sanitation practices in the
orchard and in the packinghouse, to minimize the level of infective
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