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

FREEDOM PALESTINE FREEDOM PALESTINE FREEDOM PALESTINE
284 Postharvest Diseases of Fruits and Vegetables
1. Colletotrichum gloeosporioides (Penz.) Sacc. [perfect state:
Glomerella cingulata (Stonem.) Spauld. & v. Schrenk]
Anthracnose, caused by this pathogen, is generally initiated by the
asexual state of C. gloeosporioides (acervuli with conidia), although the
sexual state (perithecia and ascospores) has been recorded. Conidia are
produced on dying leaves or petioles and are spread by rain and air
currents onto the fruit. Under moist conditions, the conidia germinate
within a few hours to form appressoria and infection hyphae, which
penetrate the cuticle and form quiescent infections in the immature fruit
(Dickman and Alvarez, 1983). Renewed growth and characteristic disease
symptoms, including fungal colonization and the development of an
abundance of salmon-pink conidia, appear when the fruit ripens after
harvest.
C. gloeosporioides is also responsible for multiple small lesions of the
'chocolate spot' type (Dickman and Alvarez, 1983), which similarly arise
from quiescent infections but only occasionally develop into anthracnose
lesions.
2. Stem-End Pathogens
Botryodiplodia theobromae Pat. and Phomopsis spp. are characteristic
stem-end pathogens of tropical and subtropical fruits.
Infection takes place by conidia (produced within pycnidia), which are
liberated and dispersed during wet conditions in the orchard.
Germinating spores penetrate via newly cut stem ends or through
crevices between the peduncle and the fruit flesh (Chau and Alvarez,
1979), but infection may also be initiated at any injury incurred by the
fruit shortly before harvest, and which has not yet healed.
Phoma caricae-papayae (Tarr) Punith. (perfect state: Mycosphaerella
caricae H.& P. Sydow) can infect uninjured developing fruit during wet
weather (Simmonds, 1965). Infection may be initiated anywhere on the
fruit surface, by asexual spores (conidia) or by sexual spores (ascospores
produced within perithecia) (Chau and Alvarez, 1979). Infection may,
however, occur via the cut stem during harvest resulting in the formation
of stem-end rot (Srivastava and Tandon, 1971).
3. Phytophthora palmivora (Butler) Butler
Phytophthora infection is initiated during the rainy season by the
asexual state of the fungus (sporangia with zoospores), although sexual
spores (oospores) have also been recorded. Following dispersal of the
lemon-shaped sporangia, the zoospores, which are liberated during wet
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