MANGO - Tropical Fruits - page 282

associated with a higher incidence. It is caused by Fusarium moniliforme , with
mites playing a minor role. A highly signifi cant reduction in malformation is
achieved, with an increase in yield, by spraying with GA 3 and NAA, singly and
in mixtures, with a second application 2 weeks later. Pruning all malformed
vegetative and fl oral fl ushes, followed by spraying with copper oxychloride
(4 g/l), is more ef ective than pruning alone to reduce the percentage
of malformed panicles and increases the yield in the following season
(Azzouz et al. , 1989).
Two other diseases with unidentifi ed causes can sometimes cause
serious loss, although little is reported in the literature. The fi rst af ects the
bark at the base of the trunk, with increased gummosis on the upper trunk
and large limbs. Wilting of branches occurs, followed by death, particularly
to trees around 8 years old. It is especially serious in Nayarit and Sinaloa
States in Mexico and has been reported from Colima State in Mexico and
from Guatemala. Both Fusarium and Phytophthora are suspected but have
not been confi rmed. The other condition is a disease of the fruit, with no
puncture wounds or insects being observed. The external symptom is a
black spot 0.5-1.5 cm in diameter, usually located at the nak of the fruit.
When the blackened area is cut, there is a hollow 'tunnel' leading to the seed
cavity. The seed and seed cavity are blackened. When the fruit is cut open,
many show the peduncular vascular system leading to the endocarp to be
disintegrated (Nakasone, 1979). It was observed to be extremely serious in
orchards of 'Tommy Atkins' in Nayarit and on 'Kent' in Campeche, Mexico,
and subsequently reported to occur in the Canary Islands and in Guatemala,
where it is called 'pepita negra'. Lakshminarayana et al. (1985) reported a
similar preharvest stem-end disease of 'Tommy Atkins' in Mexico, except that
no mention was made of the black spot on the nak of the fruit. Preliminary
studies isolated a mixture of six species of Fusarium and produced more
diseased fruit with typical symptoms than any other single isolate. Bacterial
black spot ( Xanthomonas campestris ) of the mango appears to be a relatively
serious disease in South Africa and Australia. It has also been seen in
Hainan, China.
Insect pests
Mediterranean and Oriental fruit fl ies are spread widely throughout the world.
Other fl ies are confi ned to specifi c regions, but together they constitute a
major problem, particularly to the export trade (Table 10.6). Irradiation, hot
water and vapour heat treatment have been developed to meet disinfestation
requirements in importing countries. This is probably the most important
pest of mango, since the presence of a larval form in the fruit renders it non-
exportable to many countries. Exports are generally allowed to countries
where the winters are very cold and the fl ies do not survive. The female fl ies lay