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

FREEDOM PALESTINE FREEDOM PALESTINE FREEDOM PALESTINE
Chemical Control 149
successfully controlled both preharvest and postharvest diseases in the
early 1970s (Jordan, 1973). Following the emergence of benzimidazoleresistant
B, cinerea strains because of the very specific site of action of
the chemicals (Dekker, 1977), dicarboximide fungicides (including
iprodione and vinclozolin), which have a different mode of action, were
adopted for preharvest application to soft fruits. Sprays with iprodione
several times during the flowering season have provided good control of
Botrytis rot during subsequent storage (Aharoni and Barkai-Golan, 1987;
Dennis, 1983a). In this case, the use of preharvest treatments not only
matches the mode of fungal penetration, but is probably the only way to
apply chemicals for decay control because of the great sensitivity of the
fruit to wetting. However, dicarboximide-resistant strains have also been
found on soft fruits (Hunter et al., 1987). Furthermore, similarly to the
benzimidazole compounds, the dicarboximides are also ineffective against
Mucor and Rhizopus species, and their use may result in increased
incidence of postharvest diseases caused by these fungi (Davis and
Dennis, 1979). Following the discovery of dicarboximide-tolerant
B. cinerea strains in strawberry fields and in cucumber greenhouses,
control strategies, including the use of dicarboximides in combination
with other fungicides or in rotation with an unrelated fungicide, were
developed (Katan, 1982, Katan and Ovadia, 1985; Creemers, 1992).
Field treatments are generally less effective than postharvest
treatments in controlling wound infections, since only part of the
field-sprayed fungicides will remain attached to the product to protect
wounds that occur later. In addition, fungicides that do remain on the
surface of the produce may be removed by washing and waxing (Eckert,
1978). However, several investigations have indicated that in some cases
field sprays may also be effective in reducing wound decay or lenticel
decay, because of the sedimentation of the fungicide in the infection site
and its maintenance in appropriate levels. It was thus possible to reduce
wound infection in i?/ii2:opus-inoculated peaches by sprays of dicloran
applied in the orchard 1 week before harvest, while orchard sprays with
benomyl reduced lenticel infection by Gloeosporium spp. in apples, and
orchard sprays with benomyl, thiabendazole and carbendazim in the
1970s controlled the blue mold (Penicillium expansum) and the gray
mold {B. cinerea) in stored pears (Eckert and Ogawa, 1988). Similarly,
sprays of benomyl and thiabendazole, applied in the grove 30 days before
harvest, markedly reduced the green mold (Penicillium digitatum) in
stored oranges (Brown and Albrigo, 1972; Gutter and Yanko, 1971).
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