Agriculture Reference
In-Depth Information
Provide optimum irrigation and nutrition to prevent
stress, which may favour disease development.
•
OTHER POSTHARVEST DISEASES
■
Cause
Some fungi other than
Colletotrichum
spp. may cause
postharvest disease in lychee.
Alternaria alternata
and
Phomopsis
sp. are most commonly isolated from diseased
lychee fruit. Other species involved include
Curvularia
sp.,
Fusarium
sp.,
Phoma
sp., and
Pestalotiopsis
sp.
Penicillium
sp. may cause lesions in fruit treated with sulphur dioxide.
Symptoms
Diseased areas on fruit usually have distinct margins
visible on the inner wall of the pericarp. Symptoms are
generally restricted to the pericarp, although a collapse of
the translucent f lesh beneath the diseased area may occur.
Fig 10.2 A number of fungi may be responsible for the development
of stem-end rot.
lesions may be covered with whitish masses of fungal
growth. Symptoms of infection by different fungi can
appear similar and fungal isolations are generally required
to confirm the causal organism.
Source of infection and spread
Very little is known about the infection process and spread
of stem-end rot pathogens. Infection may take place when
the fungus, which is living asymptomatically in the stems of
lychee, infects developing fruit. It is thought that this kind of
infection is favoured by poor tree health through factors
such as inadequate nutrition or irrigation. Alternatively, the
pathogen may invade the cut end of the fruit pedicel after
harvest. Spores on the surface of the fruit may wash into the
open wound and infect it.
Importance
Stem-end rot is very common and can cause significant losses
depending on factors such as tree health and causal organism.
Management
•
Prune dead leaves, twigs and fruit from canopies to
reduce inoculum levels and to improve ventilation.
Fungicide applications used to control anthracnose and
pepper spot may provide some control of stem-end rot.
•
Cool fruit rapidly after harvest and store fruit in cool
storage to reduce deterioration of fruit and reduce
development of stem-end rots.
•
Fig 10.3 Postharvest fungal disease caused by
Alternaria alternata
.
