Agriculture Reference
In-Depth Information
dispersed by wind and rain. Warm (25-28
C optimum),
wet weather favours development of the disease.
°
Importance
The disease is present in most passionfruit crops and can
severely reduce the commercial quality of fruit, resulting
in most of the crop being suitable only for processing. It
also severely defoliates vines, causing an economic loss
of production.
Management
•
Prune vines to remove dead and weak sections. This will
allow better spray penetration.
Spray with recommended protectant and curative
fungicides. Use shorter spray intervals for protectant
fungicides when vines are growing rapidly (warm,
humid weather). When fungicides with post-infection
activity are used in the program, use an anti-resistance
strategy.
•
Fig 15.4 Postharvest symptoms of anthracnose showing a collapsed
lesion.
brown spots, which may become papery with black fruiting
structures. Postharvest anthracnose, which is thought to
develop from quiescent infections, appears as a large
greasy, sunken patch on the surface of the fruit. The lesion
collapses and becomes crinkled.
Plant varieties with greater resistance to the disease.
•
ANTHRACNOSE
■
Cause
The fungus
Colletotrichum gloeosporioides
.
Source of infection and spread
The fungus is a common inhabitant of dead tissue and
is spread by rain splash and wind-driven rain. Disease
development is favoured by warm, wet weather.
Symptoms
Anthracnose is most easily recognised on leaves and stems
as tiny brown to black fruiting structures (black dots) on
dead tissue. Fruit may show symptoms before or after
harvest. Preharvest symptoms appear as superficial light
Fig 15.3 Detail of anthracnose on passionfruit.
Fig 15.5 Preharvest symptoms of anthracnose on immature fruit.
