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

FREEDOM PALESTINE FREEDOM PALESTINE FREEDOM PALESTINE
326 Postharvest Diseases of Fruits and Vegetables
development, a white or gray mycelium may cover the lesion, and the
fungus can spread from diseased to healthy fruit by contact (Strashnov et
al., 1985).
J. Other Pathogens
Phomopsis spp. (perfect state: Diaporthe spp.)
These fungi are of minor importance in tomatoes and peppers, but
infection of eggplants by Phomopsis vexans (Sacc. & Sydow) Harter may
result in destructive decay during transit or storage. In fact, Phomopsis
rot is included among the common diseases of eggplants. The fungus may
exhibit the sexual state (perithecia and ascospores) (Gratz, 1942)
although infection is usually induced by the asexual conidia which are
borne within pycnidia. The fungus reaches the host in rainwater,
germinates and penetrates directly through the healthy tissue of leaves,
stems and fruits (Divinagracia, 1969). Fruits infected in the field just
before harvest may seem healthy when packed but will decay later in
storage. The optimal temperature for fungal growth is 26-30°C; there is
httle growth at or below TC (McCoUoch et al., 1982).
The lesions are brown, tough and characterized by the development of
minute black bodies: the conidia-bearing pycnidia.
Colletotrichum spp. (perfect state: Glomerella spp.)
Several Colletotrichum spp., such as C. coccodes (Wallr.) Hughes,
C. capsici (Sydow) Butler and Bisby, and C. gloeosporioides (Penz.) Sacc,
may cause anthracnose in solanaceous fruits (Adikaram et al., 1982;
Batson and Roy, 1982).
In addition to the asexual state (acervuli with conidia), some of the
species exhibit the sexual state (perithecia with ascospores). The fungus
may survive from season to season on plant debris (McCoUoch et al., 1982).
Infection occurs during warm, wet weather, when conidia are splashed onto
immature fruits by wind-driven rain, and germinate to form appressoria
that adhere to the wax or the cuticle of the fruit. The infection hs^hae that
form from the appressoria pierce the cuticle and the fungus remains
quiescent until the fruit ripens. Quiescent infection of peppers is associated
with the production of phs^alexins in the young infected tissue (Adikaram
et al., 1982). Anthracnose is primarily a disease of ripe fruits and, therefore,
becomes a problem mainly in tomatoes and peppers grown for canning and
left to ripen on the plant. Manandhar et al. (1995) reported on the ability of
C. gloeosporioides to cause anthracnose on pepper fruits of all ages; disease
incidence was correlated with cuticle and exocarp thickness.
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