Agriculture Reference
In-Depth Information
Fig 4.30 Verticillium wilt on an avocado tree. Only part of the tree is
showing symptoms. Dead leaves remain attached on the tree for
several months.
Fig 4.29 Stem-end rot caused by anthracnose.
Harvest only mature fruit.
•
If the bark of affected branches is peeled away, a dark
brown discolouration of the underlying xylem will be seen.
Older trees generally recover but symptoms may recur
in subsequent years.
Harvest only during dry conditions.
•
Handle fruit carefully to avoid damaging the skin.
•
Minimise the time from harvest to cold storage.
•
Apply the recommended postharvest fungicides to
control stem-end rot. Controlled ripening at 16-18°C
in combination with fungicide treatment will improve
stem-end rot control. See the temperature
recommendation for controlling anthracnose.
•
Source of infection and spread
The fungus is soil-borne and may survive for many years
in the soil as microsclerotia. Many crop plants and weeds
Minimise the time from harvest to retail sale.
•
VERTICILLIUM WILT
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Cause
The fungus
Verticillium dahliae
.
Symptoms
Leaves wilt suddenly and turn brown but remain attached
to the tree for many weeks. In older trees, often only one
branch is affected, but occasionally young trees are killed.
Fig 4.31 Verticillium infection in the water conducting tissues.
Compare the dark brown discolouration of the infected stem (above)
with the healthy stem.
