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How to propagate and care for your mango tree
Part II
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Mango Propagation.
Even though cutting and air layering are methods of
vegetative propagation mangoes are usually not propagated by these
methods because of the resulting poor root system. In grafting, usually
a seed of a monoembryonic mango is planted to serve as a root stock;
when it has reached 3/8ths to 1/2 inch in diameter it is ready for
grafting. A piece of the original tree is transferred to the root stock
plant. It is this piece (the scion), bearing the genes of the
desirable fruit tree, that will bear the name and fruit of your new
tree.
Grafting techniques used are the side-tongue graft,
side-wedge, splice, and cleft. A Honolulu propagator uses the approach
or inarch method. In this method both stock and scion plants are on
their own roots at the time of grafting. This requires that the mother
tree have very low branches and young stock plants be raised to make
contact with mother tree branches to be used in grafting. Both the
mother tree and stock plant are given a tangential side cut and spliced
together. Ties to hold the two together are usually nurseryman's tape
or raffia. For those wanting to do grafting, check how these methods
are pictured and discussed in the library copy of Plant Propagation
Principles and Practices by Hartmann, Kester, and Davies or some other
reference. For the rest of us, buying a grafted tree from the nursery
is easier and more guaranteed. Request the cultivar you desire and they
will most likely be able to order it from the propagator. Grafted
trees are usually shorter and bear mangoes from 3-5 years. Seedling
trees usually bear in 5-7 years.
Planting and Watering.
Matured mango trees may occupy a space measuring 30
feet high by 30 feet wide. So check on overhead wires, underground
pipes and utilities, buildings, and neighboring trees. The tree is kind
of messy so plant it where leaf drop can be tolerated. Production
will be better if the tree is in full sun and has some kind of a wind
break - from a building or other trees. Most of the cultivars suggested
for Hawaii will do better if planted in drier parts of the island so
select your cultivar wisely. Dig a hole much larger and deeper than the
container the young grafted tree is growing in. Some compost can be
mixed in with the soil along with about 1/4th pound of fertilizer such
as 16-16-16 . Do not overuse commercial compost made with sewage sludge
due to possible burning. Even though the bag suggests one part compost
to one part soil I would use one part compost to two parts soil at the
most. Several persons told me that their trees died from using too much
of a good thing. They exceeded the bag's recommendation. Homemade
compost without manure is safe, but I would still use it at the same
ratio. Thoroughly mix the compost and fertilizer with the loosened soil
and return enough soil to the hole so that the plant ends up growing at
the same depth it was while in the container.
Remove the young tree from the container or mulch
bag. Some people say that planting with the container will "force" the
roots deeper. Containers restrict root growth. Loosening and amending
the soil with organic material will encourage deeper rooting because
oxygen and water can penetrate the soil more deeply. Because compacted
soils limit air penetration roots grow nearer to the surface to obtain
the required oxygen.
At the time of planting loosen the outer roots of the
root ball gently to encourage outward and discourage circling growth.
Plant the tree; firm the dry soil as you add it to the hole, but not to
the point that air penetration is restricted. If you firm moistened
soil it will compact and severely limit air penetration. Create a
watering basin and water immediately. Add organic mulch/compost to the
top soil but keep it away from the young tree's bark. Water every 2 or 3
days depending on the season and soil type. After the first year, once
a week watering may be sufficient. Matured trees need periodic
watering especially if they are growing in a sandy soil or if there has
been no rain. The planting technique described here can be used when
planting all types of trees.
Fertilizers.
I think most of us do not use enough fertilizers yet
we expect our trees to bear "bumper" crops. When we do fertilize we
might over apply because we were negligent previously and try to make
up. The amount of fertilizer you use will depend on the age of the
tree, its health, and whether it is a heavy bearer. You can apply one
pound the first year: one fourth pound at planting, another fourth
after four months, and a half a pound at the end of 12 months. During
the second, third, fourth, and fifth years apply two, three, four, and
five pounds to match the age of the tree. Divide the amount into three
or four portions and apply during the year. Mark this on a calendar so
that you do not forget. Thereafter apply one pound of fertilizer per
inch trunk diameter. Measure the trunk's diameter at six inches above
ground if the tree is smaller than four inches in diameter. If the tree
is between four and eight inches in diameter measure the diameter at 12
inches above ground. For matured trees greater than eight inches in
diameter, determine the trunk diameter at 54 inches above ground or just
below where the trunk branches out (for a low branching tree).
When the tree is bearing fruit, divide the fertilizer
to apply one half just before flowering and one half just after the
crop has been harvested. Broadcast the fertilizer uniformly from the
trunk out to the drip line and a little beyond. Water immediately and
as needed thereafter to make the nutrients available to the tree.
Use fertilizers with a ratio such as 1:1:1 (15-15-15) or 1:2:2
(10-20-20).
Diseases and Insects.
Anthracnose, Colletotrichum gloeosporioides, is a
dark colored fungus affecting flowers but more so fruit. Fruit with
black spots on the rind most likely have anthracnose. Powdery mildew,
Oidium mangiferae is a white (darkening to gray) fungus that affects
leaves, flowers, and young fruit. It usually causes new leafy growth to
twist, curl, and develop dark colored dead tissue. Flower clusters
look gray and the fungus is easily seen. Both fungi will cause flowers
and young fruit to drop. Sooty mold is a black fungus that is usually
found on leaves infested with scales. Scales give off honey dew that
the fungus lives off. Eliminating the scales by spraying Volck or
agriculture fine oil is the answer. Scales, aphids, white flies, and
mealybugs all exude honeydew on leaves and fruit which may lead to a
black sooty mold problem. The recommended oil treatment is good for
gardenias, citrus, etc., wherever sooty mold is a problem. Read and
follow the directions listed on the container.
To cure powdery mildew apply one tablespoon baking
soda with one tablespoon of Volck or agriculture fine oil per gallon of
water. Spray the mixture on leaves and flowers on a weekly basis
beginning when flowers first appear and until the small fruit have set.
Apply Benlate or Benomyl, a commercial fungicide to control both
powdery mildew and anthracnose. Two pounds of this fungicide can be
purchased from United Horticulture Supply on Papa Place in Kahului
(871-2622) . If smaller amounts are found at other stores you can buy
it from there. You need to take precautions when using all chemicals
(read the label) and maybe spraying just the lower branches will provide
you with enough mangoes.
My problem (and probably yours) is primarily powdery
mildew. I can use the safer baking soda cure. Benlate is probably more
effective, but for the homeowner it is more hazardous.
Insects.
The Mediterranean and Oriental fruit flies are a
problem at times. Garden shops sell baits (sex hormones) that are used
to attract male flies to a container containing an insecticide to
decrease the fruit fly population. The products are methyl eugenol for
oriental fruit flies and medlure for the Mediterranean fruit flies.
Hang the container with the chemicals on some other tree to attract the
males away from, rather than to, the mango tree. There is also a yeast
product (Stahley's bait) that is mixed with an insecticide that both
males and females eat and die. Pick up and dispose all fallen fruit.
Fruit fly larvae pupate in the ground prior to emerging as adults.
Burying fallen fruit is therefore not the solution.
Adult weevils lay eggs on small green fruit before it
is half grown. The eggs hatch and the larvae burrow into the soft seed
and remain there until becoming adults. After the fruit has ripened
and the flesh decomposed the weevils bore their way out. People eating
mangoes are unaware of seed weevils because there is no evidence of
their presence.
Because of fruit flies and the mango seed weevil,
mangoes cannot be shipped to the mainland. The State has experimented
radiating Haden mangoes and has successfully controlled the pests
without affecting the fruit. The radiation plant is located on the Big
Island. Whether mangoes are treated for export is to be worked out. I
think Hawaii can consume all the fruit we produce. Some areas where
flies and weevils do not survive the harsh winters (like Canada) already
import mangoes without a quarantine. However our pests do limit
exports of fruit and controlling or eliminating them would really open
up agriculture opportunities.
My Experiment.
This is the fun part. I obtained mangoes from Frank
Swan of Maui Meadows, Maui Tropical Plantation, and Yee's orchard in
Kihei. I photographed them and my wife and I sampled them for fiber
content, taste, seed size, and skin color. The results are:
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