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

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Postharvest Disease Summary 311
may be one of the main pathogens of blueberries and gooseberries
(Dennis et al., 1976). Similarly, Phomopsis spp., which are generally of
minor importance in strawberries, may be of greater importance in
harvested blueberries (MilhoUand and Daykin, 1983). Other fungi
responsible for postharvest rotting include species of Cladosporium,
Penicillium and Pestalotia (Snowdon, 1990). The incidence of the less
common or minor pathogens may vary from year to year, from season to
season and from place to place, suggesting that climate factors may affect
the amount of inoculum available or the infection resistance of the fruit
(Dennis, 1983a).
STRAWBERRIES AND RASPBERRIES
A. Botrytis cinerea Pers. [perfect state: Botryotinia fuckeliana (de
Bary) Whetzel]
The gray mold fungus is a most important pathogen of soft fruits,
worldwide. It survives on organic debris in the field, frequently as
sclerotia, and under favorable conditions it sporulates, releasing quantities
of spores that serve as a potential source of inoculum for infection of
flowers (Braun and Sutton, 1987). Temperature and duration of humidity
have the greatest effects on inoculum production: the optimal temperature
for sporulation is between 17 and 18''C, but under sustained humidity the
temperature range for profuse sporulation extends to 15-22°C
(Sosa-Alvarez et al., 1995). Under alternating wet and dry periods, the
total duration of high humidity and the length of wet periods determine
the amount of inoculum produced. No sporulation occurs at 30°C.
During the flowering and fruiting season fungal spores are common in
the atmosphere (Jarvis, 1962), and at harvest time the fruit is already
contaminated with Botrytis spores. Conidia are deposited on flowers by
air or water (Braun and Sutton, 1987) and primary infection of
strawberries takes place through senescent floral parts where the conidia
remain quiescent in the base of the receptacle. Disease is manifested as
stem-end rot only when the fruit ripens (Powelson, 1960), so that the
fruits may be harvested in apparently sound condition only to decay
during transit and marketing (Aharoni and Barkai-Golan, 1987).
In raspberry fruits the fungus invades stigmas and styles, resulting in
infection of individual fruitlets (Williamson and McNicol, 1986).
Mummified fruits and receptacles entirely covered with fungal spores are
often found on raspberry plants. After harvest, infections of strawberries
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