From the Manual Of
Tropical And Subtropical Fruits
by Wilson Popenoe
The Mango
Pests And
Diseases
The commonest and most troublesome enemy of the mango in tropical
America is anthracnose. This is a parasitic fungus (Colletotrichum gloeosporioides Penz.)
which attacks many different plants, and is particularly known as the
cause of wither-tip in citrus fruits. It is a species of wide
distribution which springs up with no evident center of infection
whenever the weather is warm and moist. On the flowers and
flower-stalks of the mango it appears in the form of small blackish
spots. Often it causes many of the flowers to drop. On the leaves,
spots and sometimes holes are produced; these begin as minute black
dots and enlarge until they are about an eighth of an inch in diameter.
Young fruits may be attacked and made to drop in large numbers, while
older fruits become spotted with black or streaked, and their keeping
qualities are impaired.
S. M. McMurran, who studied anthracnose
control methods in Florida and reported his results in Bulletin 52 of
the United States Department of Agriculture, says:
"Spraying
before the buds begin to grow is of no value so far as protecting the
inflorescence, and later the young fruit, is concerned. These must be
kept covered with the fungicide (Bordeaux mixture) while growing, if
fungous invasion is to be prevented. The difficulty of so protecting
the inflorescence is at once apparent. Elongations of the panicle
continue for a period ranging from 10 to 15 days. Those which were
sprayed every third day were practically all disease-free when the
flowers began to open. This, however, required four sprayings in one
case and six in the other. Those sprayed every fourth day showed but
little more disease than those sprayed every third day, but those on
which the spray was applied at five and six day intervals had traces of
disease, showing that they were less perfectly protected.
"The
spraying of the inflorescence at least three times, beginning when the
buds are just swelling and repeated every fourth day until the flowers
open, will help to prevent the dropping of fruit caused by the disease
on the peduncles and pedicels.
"The inflorescence may be kept in
a clean condition up to the time of blooming; but, when this takes
place, immediately there are hundreds of points which are not covered
by the fungicide and are open to infection . . spraying is of little
or no value in controlling the blossom blight form of the disease, and
profitable sets of fruit can be expected only during seasons which are
dry at blooming time, unless varieties which are resistant to the
disease are developed and cultivated."
This disease is a serious obstacle to the production of marketable
mangos in the West Indies. J. B. Rorer,1
who conducted spraying experiments in Trinidad, found, however, that
"All of the sprayed trees set more fruit than the control trees, and
the greater part of the fruit ripened without infection, while the
fruit on unsprayed trees was for the greater part spotted or
tear-streaked. The fruit from sprayed trees matured a little later than
that from the unsprayed and was somewhat larger in size. The foliage of
sprayed trees was much heavier than that of the unsprayed." If fruit is
not sprayed to keep it clean while it is developing, it not only is
less attractive when placed on the market, but is subject to decay.
Anthracnose
does not appear to be mentioned by Indian writers on mango culture. It
is known, however, to be serious in Hawaii as well as in tropical
America. Bordeaux mixture used in its control can be made according
either to the 4-6-50 or the 5-5-50 formula, using a small amount of
whale-oil soap to make it adhere more tenaciously to the foliage.
Ethel
M. Doidge, in the Annals of Applied Biology (1915) describes a
disfiguring and rotting disease of mangos which occurs in South Africa.
It is caused by Bacillus
mangiferoe,
an organism which is carried by water or may be transported from tree
to tree by the wind. Woody tissues are not affected, but small angular
water-soaked areas appear on leaves, longitudinal cracks are produced
on petioles, and discolored spots on twigs and branches; while on the
fruit the first sign of the disease is a small discolored spot. This
spreads, becoming intersected with cracks, and may extend some distance
into the flesh. No means of controlling this bacterial disease has yet
been discovered.
1 Trinidad
and Tobago Bull. 5, 1915.
Of
the insects which attack the mango, the fruit-flies (Trypetidae) rank
first in importance. Belonging to this family are the Mediterranean
fruit-fly (Ceratitis
capitata Wiedemann), which has become a very serious pest
in Hawaii and several other regions; the Queensland fruit-fly (Batrocera tryoni
Froggatt), distributed throughout Malaysia and Australia; the mango
fruit-fly (Dacus
ferrugineus Fabricius), which occurs from India to the
Philippines; the Mexican fruit-fly (Anastrepha
ludens Loew); and Anastrepha
fraterculus
Wiedemann, another Mexican species, now distributed throughout Central
and South America and the West Indies. Several other species have also
been reported as attacking the mango. The females of these flies insert
their eggs beneath the skin or in the flesh of the fruit, and the
larvae render it unfit for human consumption. Control is difficult; the
sweetened arsenical sprays have met with varied success, and control by
means of parasites is receiving attention.
In some parts of India the mango hopper (various species of Idiocerus) is
troublesome. H. Maxwell-Lefroy1 writes:
"These
insects resemble the Cicadas superficially but are much smaller, being
one-sixth of an inch in length. They are somewhat wedge-shaped with
wings sloped at an angle over the back. Large numbers are found on the
mango trees throughout the hot weather but especially at the flowering
season when there is a flow of sap to the flowering shoots. These
insects pass through their active life on the tree, sucking the juice
of the soft shoots and causing them to wither. There is only
one
effective treatment which must be adopted vigorously. This is spraying
with strong contact poison such as crude oil emulsion or sanitary
fluid."
1 Indian
Insect Pests.
Another serious pest in India is the mango weevil (Sternochetus mangiferoe
Fabricius, better known as Cryptorhynchus
mangiferce).
It is not limited to India, but is found also in the Straits
Settlements, the Philippines, South Africa, and Hawaii. In the
last-named country it has become formidable. "The insect is a short,
thick-set weevil, dark brown in color, one-third of an inch in length.
. . . The grubs bore in the kernels of the mango fruit when it is
growing large; these grubs pupate inside the fruit and as the mango
ripens become beetles, eating their way out through the pulp of the
fruit, which they spoil." Maxwell-Lefroy recommends that all infested
fruits be destroyed, and that weevils hiding in the bark of the tree be
killed in August. Kerosene emulsion is useful in destroying those which
are on the bark. It is also advisable to cultivate or flood the ground
beneath the trees, in order to kill weevils which may be lurking there.
In
Florida, red-spiders and thrips are responsible for extensive injury to
foliage, leading to disturbances of the general health of the trees;
but contact sprays, e.g., lime-sulfur or nicotine, properly applied,
will effect complete eradication.
The mango bark-borer (Plocoederus
ruficornis Newman) is a formidable enemy of the mango in
the Philippines. This is a large beetle. C. R. Jones1
says of it:
"The
mango bark borer, while a comparatively unknown pest outside the
vicinity of Manila, is exceedingly dangerous, largely on account of its
feeding habits, which make detection difficult. The beetle has, so far
as we know, no natural enemies, being fully protected both in the
larval and pupal stages. Physical remedies are, therefore, necessary,
such as the removal of larvae and pupae from their burrows by hand."
The mango shoot psylla (Psylla
cistellata
Buckton) is reported only from India. "It injures the terminal shoots
by producing imbricated pseudo-cones of a bright green or yellow color
in which the larval and pupal stages are passed." Dinoderus distinctus
is a beetle which attacks branches of the mango in India. Sternochetus gravis
is the mango weevil of northern India, similar to the common mango
weevil described above. These and many other insects reported as
attacking the mango in various parts of the world are described in "A
Manual of Dangerous Insects," published by the United States Department
of Agriculture (1917). The scale insects are particularly numerous, and
cannot be listed here. Several of them are common in the mango orchards
of Florida. The genera Aspidiotus,
Chionaspis, Coccus, Pulvinaria, and Saissetia are well
represented in different parts of the world. Generally speaking, their
control by spraying is relatively simple.
1 Philippine
Bur. Agr. Circ. No. 20.
The
Mango
Botanical
Description
History and
Distribution
Composition
And Uses Of The Fruit
Climate
And Soil
Cultivation
Propagation
The Mango Flower
And Its Pollination
The
Crop
Pests And
Diseases
Races and
Varieties
Back to
The Mango Page
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