Agriculture Reference
In-Depth Information
Symptoms
Fruit do not usually show any external symptoms.
Internally, the formation of corky tissue on the walls of
the fruitlets makes them leathery and brown.
Source of infection and spread
See fruitlet core rot.
Importance
Leathery pocket occurs sporadically in Queensland
pineapple crops.
Fig 16.12 Internal symptoms of a
Phytophthora cinnamomi
infection.
Management
See fruitlet core rot.
INTERFRUITLET CORKING
■
PHYTOPHTHORA HEART (TOP) ROT
■
Cause
The fungus
Penicillium funiculosum
, which also causes
fruitlet core rot and leathery pocket.
Cause
The oomycetes
Phytophthora cinnamomi
, which also causes
severe root rot and green fruit rot, and
Phytophthora
nicotianae,
which
also causes heart rot and a minor root rot.
Symptoms
Fruit affected by interfruitlet corking often show shiny
patches on the shell early in their development, where the
trichomes (hairs) have been removed by mite feeding.
Symptoms
Heart rot occurs with both
P. cinnamom
i and
P. nicotianae
.
Plants of all ages are attacked, but three- to four-month-old
crown plantings are most susceptible. Sometimes, fruiting
plants or suckers on ratoon plants may be affected. The
first symptom is a colour change of the heart leaves to
yellow or light coppery brown. Later, the heart leaves wilt
(causing the leaf edges to roll under), turn brown and
eventually die.
Externally, corky tissue develops on the skin between the
fruitlets, but usually only 'patches' of eyes are affected.
Fine, transverse cracks may also develop on the sepals and
bracts. In moderate to severe cases, corkiness surrounding
fruitlets prevents their development and one side of the
fruit will be malformed.
Once symptoms become visible, young leaves are easily
pulled from the plant, and the basal white leaf tissue at the
Source of infection and spread
See fruitlet core rot.
Importance
Interfruitlet corking is limited almost exclusively to fruit
initiated in early autumn. It is sporadic and often confused
with boron deficiency.
Management
See fruitlet core rot.
LEATHERY POCKET
■
Cause
The fungus
Penicillium funiculosum
, which also causes
fruitlet core rot and interfruitlet corking.
Fig 16.13 Heart rot caused by
Phytophthora cinnamomi
. The
background shows healthy plants.
