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

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Postharvest Disease Summary 281
Studying the potential for biocontrol of Lasiodiplodia theobromae in
banana fruits, Mortuza and Ilag (1999) found that Trichoderma viride is
capable of reducing rotting by up to 65% in inoculated banana fruits. The
time of application of the antagonist and the inoculum levels of both the
pathogen and the antagonist are important factors in the biocontrol
activity. The best activity was exhibited at high concentrations of the
antagonist and low concentrations of the pathogen, and when the
antagonist was applied 4 hours prior to the pathogen.
MANGO
The most serious postharvest diseases of mango are anthracnose,
caused by Colletotrichum gloeosporioides; and stem-end rot, caused by a
complex of fungi, of which Botryodiplodia theobromae is the most
common.
1. Colletotrichum gloeosporioides (Penz.) Sacc. [perfect state:
Glomerella cingulata (Stonem.) Spauld. & v. Schrenk].
This pathogen causes anthracnose, which is responsible for severe
losses of fruit in all mango-growing countries. It is the same fungus that
causes anthracnose in avocado, citrus and papaya fruits.
C. gloeosporioides may exhibit both the asexual state (acervuli with
conidia) and the sexual state (perithecia and ascospores). The asexual
conidia are produced in wet seasons on dead twigs and leaves, from
which they are washed down to the fruit. Perithecia have also been
found on dead twigs and leaves but they probably do not play an
important role in anthracnose infection (Fitzell and Peak, 1984).
Disease is initiated by conidia in unripe mango fruits in the plantation,
the fruit being susceptible to infection from blossoming and during its
developmental stages on the tree. Germinating conidia give rise to
appressoria, but at this stage or after the production of fine
subcuticular hyphae, the infection remains quiescent. Fungal growth is
renewed only when the fruit ripens (Daquioag and Quimio, 1979). The
resistance of unripe mango fruits has been attributed to the presence of
preformed antifungal compounds in the peel, which act on the
subcutaneous hyphae from germinating appressoria (Prusky and Keen,
1993). A fruit with quiescent infection, without any visible symptoms, is
liable to be stored and will start to rot later, during storage or
marketing.
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