Agriculture Reference
In-Depth Information
Infection is mainly from conidia even though there is also
a sexual stage of the fungus. The disease cycle has not been
fully described.
fungal growth on the fruit surface. The main difference
between the two diseases is that growth from sooty mould
is easily removed by brushing, whereas that from sooty
blotch is not.
In dry areas, prolonged rain at f flowering and early fruit set
can favour development of mango scab. It can also be
observed on young seedlings in mango nurseries where
lush, young tissue, combined with frequent irrigation,
provide ideal conditions for its development.
Source of infection and spread
Infection is favoured by warm, wet weather. Spores of
Stomiopeltis
sp. are produced in large numbers after rain
from infected tissues.
Importance
Mango scab has been detected in most mango growing
regions of the world, but remains a minor disease in most
of these regions, including Australia. The disease was first
identified in Australia in an orchard near Darwin in 1997.
It appears to have been in the Northern Territory and
Queensland since the early 1990s but then thought to be
anthracnose of f flowers. In the early stages of development,
the symptoms are easily confused with anthracnose
symptoms.
Importance
Sooty blotch is a minor disease, seen mostly in unsprayed
orchards under wet conditions.
Management
•
Copper and strobilurin fungicides for anthracnose
control may help control this disease.
After harvesting, treat fruit on the packing line with a
disinfectant to remove the dark, superfi cial fungal growth.
•
The disease is not widespread in mango growing orchards
in the Northern Territory or Queensland mainly because
copper sprays in anthracnose management programs
indirectly keep it under control. Scabbed fruits would be
rejected or downgraded if infection levels were high.
Management
Copper sprays applied to control anthracnose will provide
some protection against scab. In countries where copper
fungicides are registered for scab control, the following is
recommended:
In young mango nurseries, apply weekly copper fungicide
sprays to protect the young, succulent tissue from
infection under irrigated, moist conditions.
•
Fig 12.36 Symptoms of sooty blotch on mango fruit.
In older orchards with the disease, start copper fungicide
spray applications as soon as fl ower panicles appear and
continue until after the fruit set.
•
Older fruits are generally not susceptible and thus there is
no need to spray fruit larger than golf-ball size.
•
SOOTY BLOTCH
■
Cause
An unidentified fungus, probably
Stomiopeltis
sp.
Symptoms
Sooty blotch appears as a black, superficial blemish on
branches, stems and fruit. It should not be confused with
sooty mould, which also appears as a dark, saprophytic,
Fig 12.37 Severe symptoms of sooty blotch on mango.
