Agriculture Reference
In-Depth Information
unripe fruit
during fruit ripening
conidium
appressorium
infection peg
wax layer
cuticle
epidermal cell
infection restricted to outer layer of fruit skin -
no symptoms visible at this stage
infection develops in fruit
and symptoms appear
conidia are washed onto
developing fruit by rain
conidia are produced in fruiting bodies
on the surface of lesions
conidia increase in the tree canopy
Fig 2.4 Disease cycle of avocado anthracnose caused by
Colletotrichum gloeosporioides
.
Symptoms and life cycle
Large numbers of spores (conidia) form in acervuli
in lesions on foliage, branches, twigs and fruit.
The fungus is most active during warm, wet
conditions and the spores disperse by rain splash.
Young growth on new leaf f flushes is the most
susceptible to infection. Fruits can be infected at
any stage of development. Spores germinate on the
fruit surface, producing an infection structure
(an appressorium). This produces an infection peg,
which penetrates the fruit skin. Here it remains
dormant or quiescent until fruit begins to ripen.
The fungus then resumes activity and rapidly invades
the fruit, causing extensive decay.
Management
Effective management of the pathogen includes orchard
hygiene and good crop management, pre- and postharvest
fungicide applications, postharvest temperature and
ripening management, and resistant varieties, where
available. Further details are provided in specific sections
for each crop.
ARMILLARIA ROOT ROT
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Cause
The fungus
Armillaria luteobubalina
.
Hosts
Colletotrichum gloeosporioides
causes important problems,
particularly as a fruit pathogen, on most tropical fruit
crops including avocado, breadfruit, carambola,
cherimoya, citrus, durian, fig, guava, lychee, mango,
papaya, passionfruit and rambutan.
Importance and hosts
Armillaria luteobubalina
is a native fungal pathogen
distributed widely in Australian native forest and
woodland areas. The fungus infects more than 200 species
across more than 50 plant families, and most host species
are endemic to Australia.
