Agriculture Reference
In-Depth Information
material is the primary means of spread to new fields,
and infected fruit provide inoculum for stem infections,
particularly in cultivars with a collar-of-slips habit.
Insects and wind are the primary means by which the
fungus spreads from infected to healthy plants.
protecting the inf lorescence and young fruit with
fungicides.
Although most strains of F. guttiforme cause fruitlet
core rot, some strains cause fusariosis. Besides
symptom development, there is no test available to
distinguish the strains, so identification requires
pathogenicity testing.
Importance
The disease is confined currently to South America
where fruit losses have reached 80% under severe
disease conditions. Smooth Cayenne is highly
susceptible.
What to do if you suspect fusariosis
This pathogen is a biosecurity risk to Australia. Any
suspected affected plants should be reported to the
nearest Department of Primary Industries or the Plant
Health Australia hotline (1800 084 881).
F u is a r i o is i is i is c o n t r o l l e d b y p l a n t i n g d i is e a is e - f r e e
propagation material, controlling insects and
Management
The sporadic nature of the disease makes chemical
control impractical and uneconomic. Miticide
applications at fl ower induction and three weeks after
forcing can reduce disease.
GREEN FRUIT ROT
Cause
The oomycete Phytophthora cinnamomi , which also causes
root and heart rot.
Symptoms
Green fruit in contact with the soil are liable to be infected.
Initially, a water-soaked rot develops internally behind
affected fruitlets with no external symptoms. As the
disease progresses, a general, water-soaked rot of green
fruit with a distinct brown margin develops in green fruit.
Source of infection and spread
The pathogen lives in the soil and requires free water for
spore production and fruit infection. Ratoon crop fruit
lying close to or touching soil are most affected. Spores
may be splashed by rain on to fruit near the ground.
Importance
Green fruit rot infection is generally minor but serious
losses may occur in ratoon crops following heavy rain
when plants have fallen (lodged) as a result of root rot.
Management
Apply the systemic chemicals that are used to control root
and heart rot.
Fig 16.11 External symptoms of green fruit rot caused by Phytophthora
cinnamomi .
Search WWH ::




Custom Search