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

FREEDOM PALESTINE FREEDOM PALESTINE FREEDOM PALESTINE
250 Postharvest Diseases of Fruits and Vegetables
integration of early harvest, low fruit nitrogen, high fruit calcium, yeast
or yeast + one-tenth of the label rate of thiabendazole, along with a
controlled atmosphere (2% O2, 0.6% CO2), was found to reduce blue mold
severity in inoculated fruit by 95, 61 and 98% in three successive years,
after 2-3 months at 0°C. Side rot caused by P. malorum was completely
controlled when the combined treatments included the antagonistic
Cryptococcus, early harvest and high fruit calcium.
Control of brown rot of sweet cherry was achieved by postharvest
application of a combination of the antagonistic yeast C. laurentii or
C. infirmo-miniatus, with low doses of iprodione to the fruit (Chand-Goyal
and Spotts, 1996b). However, following the ban on the application of
iprodione less than 7 days before harvest, Spotts et al. (1998) showed that
a combination of a single preharvest treatment with iprodione, in
conjunction with postharvest biological control by C. infirmo-miniatus,
gave significantly better control of the brown rot in stored sweet cherries
than iprodione alone, although the yeast by itself had no suppressive effect
on decay development. The effectiveness of such a combined treatment
resulted from the fact that M fructicola was sensitive to the residues of
iprodione, whereas the antagonistic yeast was resistant to them.
In contrast to its lack of effect on M fructicola, the yeast alone did
suppress the development of P. expansum, which infected cherry fruits
naturally. Combinations of preharvest iprodione and postharvest
Cryptococcus applications resulted in the prevention of blue mold
infection in storage (Spotts et al., 1998).
In addition, brown rot in sweet cherries, which was reduced by
modified atmosphere packaging alone, could be further reduced as a
result of synergism between the antagonistic yeast and the modified
atmosphere. The O2 and CO2 percentages within the sealed package,
after 42 days of storage at 0.5°C, were 11.4 and 5.1%, respectively;
reduction of decay under these conditions was attributed to the
accumulation of CO2 in the atmosphere. Furthermore, when CO2
dissolves in water, carbonic acid is produced and the pH is lowered.
Such conditions may favor yeast growth. Thus, the Cryptococcus-MA
synergism may result from a combination of suppression of M fructicola
and stimulation of C. infirmo-miniatus (Spotts et al., 1998). When these
two postharvest treatments - biological control and modified
atmosphere packaging — were combined with preharvest iprodione
spray, the incidence of the brown rot was reduced from 41.5% in the
control to only 0.4%.
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