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

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Chemical Control 161
of thiabendazole-resistant Colletotrichum musae isolates has been
reported in banana plantations that have commonly received pre- and
postharvest thiabendazole treatments (de Lapeyre de Bellaire and
Dubois, 1997). The ability of the benzimidazoles to persist in the fruit
throughout the storage period ensures continuous contact with the
pathogen, which exerts continuous pressure for selection of
benzimidazole-resistant strains with various degrees of resistance. In
addition, pathogens which develop resistance toward one benzimidazole
compound, show a *cross-resistance' to other compounds with similar
chemical compositions and structures (Eckert and Ogawa, 1985).
The emergence of fungal strains resistant to benzimidazoles, and the
resulting decrease in the efficacy of the postharvest benzimidazole
treatments, raise questions about the future use of these compounds in
the control of Penicillium rots in citrus fruits and apples and of Botrytis
rot in various fruits and vegetables. The risk of the emergence of such
resistant strains significantly increases when these compounds are
applied as both pre- and postharvest treatments in certain crops.
In order to broaden the scope of benzimidazole activity, as well as to
solve the problem of the emergence of resistant strains, their
combination with a fungicide of a different chemical structure and a
different mode of action, was suggested. It is thus possible to use a
combination of benomyl and prochloraz in order to control both
Penicillium and Alternaria in pears stored at 0.5°C (Sitton and Pierson,
1983). A combination of benomyl and dicloran is effective in controlling
the two main decays in stone fruits: the brown rot caused by Monilinia,
and the watery rot caused by Rhizopus (Wade and Gipps, 1973).
Similarly, a combination of TBZ and iprodione controls both
TBZ-resistant and TBZ-sensitive Botrytis strains in stored celery
(Barkai-Golan et al., 1993a), and is effective against both Botrytis and
Alternaria in white cabbage, although it is ineffective against bacterial
soft rots in this crop (Geeson and Browne, 1979). Thiabendazole and
dicloran dust, applied to white cabbage in alternate years, was
recommended by Brown and collaborators (Brown, A.C. et al., 1975) to
minimize the development of benzimidazole-resistant strains of
B. cinerea in storage. For solving the problems associated with the
emergence of benzimidazole-resistant strains of P. expansum in pears,
TBZ was combined with captan, and this combination was alternated
with another fungicide (imazalil, etaconazole or iprodione). Such a
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