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

FREEDOM PALESTINE FREEDOM PALESTINE FREEDOM PALESTINE
170 Postharvest Diseases of Fruits and Vegetables
The Use and Development of Fungicides - Perspectives
It should be emphasized that the use of a fungicide or bactericide is
not a substitute for appropriate storage conditions, since these
compounds only seldom affect the physiological deterioration of the
product. Moreover, chemical compounds are more effective when the
fruit or vegetable is held under storage conditions which maintain the
natural infection resistance of the produce, but are not good for the
growth of the pathogen. However, when appropriate refrigeration or a
controlled atmosphere cannot be installed, the chemical treatment may
be the only means available to prolong the postharvest life of fruits and
vegetables.
In the past, the selection of fungicides for development was largely
based on their fungicidal performances and safety to the consumer and
operator. However, there is now a greater awareness of the need to
define other aspects of new fungicides early in the development process.
According to Knight et al. (1997) these include, in addition to
cost-effective fungicidal activity: low toxicity to humans and wildlife, low
environmental impact, low residues in food, and the ability to integrate
with other disease control technologies. Examples of substances with low
environmental impact and low residues in the treated commodity are
compounds that are 'generally recognized as safe' (GRAS) and naturally
occurring plant products, as given below.
D. GENERALLY RECOGNIZED AS SAFE (GRAS)
COMPOUNDS
Fungicides that leave low or non-detectable residues in the commodity
are actively sought in research programs. Compounds are selected that
rapidly degrade on the host surface or metabolize quickly in the tissue.
Hydrogen peroxide is such a compound; it degrades into O2 and H2O
leaving no harmful residue, and is considered a generallyrecognized-as-safe
(GRAS) compound by the Food and Drug
Administration of the USA. Vapor phase hydrogen peroxide treatment
was found significantly to reduce the number of germinable Botrytis
cinerea spores on grapes. It also resulted in reduced decay in
non-inoculated 'Thompson Seedless' and 'Red Globe' grapes after 12 days
of storage at 10°C, without affecting grape color or soluble solids content
(Forney et al., 1991).
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