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

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Postharvest Disease Summary 291
spray with gibberelic acid (GA3), applied in the orchard 10-14 days before
harvest, delays fruit softening and extends the storage life of the fruit
(Ben-Arie et al., 1986). Following three GA3 sprays (20 |Lig ml-i) during the
development of the fruit in the orchard, the cal5^ was found to remain erect
until harvest and a smaller area was covered with the black spot disease
after 3 months of storage at 0°C. GA3, at concentrations of up to 200 |Lig ml-i,
had no direct effect on fimgal growth in vitro or on inoculated fruit, and the
effect of GAs on disease development was attributed to the enhancement
of fruit resistance to infection (Perez et al., 1995).
GUAVA
The fact that the guava fruit peel is easily broken leads to postharvest
infections by many wound pathogens (Eckert, 1990). These include:
Colletotrichum gloeosporioides, Botryodiplodia theobromae, Ceratocystis
paradoxa and species of Phomopsis, Phoma, Fusarium, Pestalotia,
Penicillium, Aspergillus, Rhizopus, Mucor and Erwinia (Adisa, 1985b;
Arya et al., 1981; Brown, B.I. et al., 1984; Singh and Bhargava, 1977;
Ramaswamy et al., 1984; Wills et al., 1982).
1. Colletotrichum gloeosporioides (Penz.) Sacc. [perfect state:
Glomerella cingulata (Stonem.) Spauld & v. Schrenk]
Anthracnose, caused by this pathogen, is the most significant disease
of guavas (Adisa, 1985). The fungus, which characteristically also infects
other tropical and subtropical fruits, attacks most cultivars of guava,
although several cultivars have been found to offer some resistance
(Tandon and Singh, 1970).
2. Botryodiplodia theobromae Pat.
Botryodiplodia rot, caused by this pathogen, is another disease
common to various tropical and subtropical fruits. It may invade guavas
in the orchard, causing a dry stem-end rot of developing fruits. Decay of
ripe fruits results from infection through the stem end or via wounds and
causes a soft breakdown of the tissue (Adisa, 1985; Srivastava and
Tandon, 1969).
3. Phom^opsis spp.
Infection by these pathogens may also be initiated either in the
orchard or after harvest (Srivastava and Tandon, 1969); it usually occurs
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