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

FREEDOM PALESTINE FREEDOM PALESTINE FREEDOM PALESTINE
160 Postharvest Diseases of Fruits and Vegetables
control of banana crown rot caused by several fungi (including
Colletotrichum, Fusarium, Verticillium, Botryodiplodia and Cephalosporium)
and anthracnose {Colletotrichum), carbendanzim and thiophanatemethyl
were superior to TBZ, but both were slightly inferior to benomyl
(Eckert, 1990).
The benzimidazole compounds are insoluble in water but are fairly
soluble in dilute acids and alkalis. They are generally applied to fruits as
water suspensions or in wax emulsions, but may also be applied as
solutions in a hydrocarbon solvent used in the formulation of fruit
coating (Eckert, 1975). TBZ is stable under postharvest application,
whereas benomyl is unstable and decomposes slowly in water to
methyl-2-benzimidazole carbamate (MBC). MBC is only slightly less
active than benomyl and probably plays a major role in disease control.
However, its penetration ability into the tissue is very small (Eckert,
1978).
One of the limitations of the benzimidazole compounds is that they are
not active against a number of important postharvest pathogens, such as
Rhizopus, Mucor, Phytophthora, Alternaria, Geotrichum and soft rot
bacteria (Eckert and Ogawa, 1988). Because of its lack of activity against
these pathogens, benzimidazole cannot be used alone to control total
decay in storage. Furthermore, the resistance of these pathogens towards
the benzimidazole compounds may result in changes in the normal
balance that naturally exists within the pathogenic population of each
product. Thus, diseases of relatively little importance, incited by
Alternaria and Geotrichum in citrus fruit or by Alternaria in white
cabbage and in zucchini squashes, may become a limiting factor in
storage of these products (Albrigo and Brown, 1977; Temkin-Gorodeiski
and Katchanski, 1974; Wale and Epton, 1981). Furthermore, of the two
species of Penicillium which attack citrus fruits, P. digitatum has proven
to be more sensitive to the benzimidazoles; continuous treatment of
citrus fruits with these fungicides resulted in a remarkable increase in
decay by P. italicum, the less sensitive fungus of the two (Gutter, 1975).
A very serious problem arising from long and continuous treatment
with the benzimidazole compounds, is the development of fungal strains
resistant to these fungicides, as a result of the heavy selection pressure
exerted by the chemicals on the pathogen populations, (Georgopoulus,
1977). Common examples are the resistant strains of P. digitatum and
P. italicum in citrus fruit, of P. expansum in pome and stone fruits, and
of B. cinerea in various crops, that have frequently been reported within
the natural sensitive population of these species. Recently the appearance
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