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

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Postharvest Disease Summary 279
(Laville, 1974), and suppress growth of the fungus Trichoderma, whose
minimum growth temperature is about 5°C (Gutter, 1963).
BANANA
The most important diseases of bananas are: crown rot, caused by a
complex of pathogens; anthracnose, incited by Colletotrichum musae; and
fruit rot, caused by Botryodiplodia theobromae.
1. Crown Rot Fungi
Several fungi may be involved in banana crown rot, which is the
principle cause of postharvest disease losses of bananas in international
trade. They include C. musae, (Berk. & Curt.) v. Arx, Fusarium spp.
[mainly F. pallidoroseum (Cooke) Sacc], Verticillium theobromae (Turc.)
Mason & Hughes, B, theobromae Pat., Acremonium spp., Cephalosporium
spp. and Ceratocystis paradoxa (Dade) Moreau.
Crown rot pathogens commonly grow saprophytically and sporulate on
senescent flower parts and leaf debris in the plantation. The spores are
spread to the developing hands by rain splash and wind (Meredith,
1971). Harvested bananas carry the spores of pathogenic fungi into the
tank of water, in which they are floated to permit latex to flow from the
cut tissue of the crown (the portion of the node that has been severed
from the stem). The tank (or the 'dehanding' tank) is believed to be the
major site of crown rot inoculation, and the newly exposed tissue is
vulnerable to infection (Eckert, 1990; Shillingford, 1977).
2. Colletotrichum musae (Berk. & Curt.) v. Arx
This fungus is one of the components of the crown rot complex, and the
principle cause of banana anthracnose: one of the major diseases of
bananas in all producing countries. The fungus exists on debris in its
asexual state, as conidia located in a special acervulus. Spores are
liberated by rain splash or irrigation water and dispersed by air currents
onto young green fruits. Following germination under moist conditions,
the conidia produce appressoria, which remain quiescent on the fruit
skin. When the fruit ripens and its susceptibility to invasion increases,
the fungus becomes active and infects the fruit. The presence of an
antifungal compound in the unripe banana fruit has been related to the
latency of C. musae in this fruit (Mulvena et al., 1969).
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