School Science Lessons
Pineapple Project
Updated: 2008-03-29
Please send comments to: J.Elfick@uq.edu.au
See also: Interesting
websites
Table of contents
Preface
1.0 Introduction to the Pineapple Project
2.0 Parts of the plant
3.0 Soils for growing pineapples
4.0 Leaves
5.0 Roots
6.0 Flowering and forcing
7.0 Planning the pineapple garden
8.0 Types of planting material
9.0 Selecting plants for planting material
10.0 Planting
11.0 Pineapple growing
12.0 Keeping records
13.0 Fertilizers
14.0 Pests of pineapples
15.0 Weeds
16.0 Improving pineapple production
17.0
Understanding the records
Preface
Before teaching this project, discuss the content of the lessons with
a field officer of the Ministry of Agriculture and get advice on
planting
material, planting distances, site for planting, approved mulch,
composting,
and control of pests and diseases. Use only the procedures,
agricultural
chemicals and insecticides recommended by the local field officer of
the
Ministry of Agriculture. If you cannot control insects by hand-picking,
ask the Ministry of Agriculture to recommend a chemical spray. All
insect
sprays are dangerous. Show the students how to use them safely. Do not
get the spray onto your hands. Do not breathe in the spray. Wash your
hands
well after using spray. Keep the spray container in a safe place where
students cannot get it. Spray on a day of no wind but if you must spray
when there is a wind, spray down wind. Make sure the spray does not
blow
on other people.
Start planting as early as possible in the year but make sure you can
get enough planting material. Do not make the garden too big. A smaller
garden with bearing good fruit is better than a big garden that is
untidy
and has poor quality fruit. In some places pineapple growing is not a
good
standard. In some places the pineapples do not produce good fruit as
well
as they could and growers do not make much money from them. Ask the
local
agriculture department officer to help you with information and
practical
help.
1. To improve pineapple production pay
attention to the following:
1.1 Know how to choose better planting material.
1.2 Take care with weeding and stopping pests and diseases.
1.3 Giving pineapples enough fertilizers of the right kind.
1.4 Handle fruit carefully.
2. Before you begin the project, make sure that you have the following
materials:
2.1 Digging tools, spades
2.2 Hoes for weeding and shaping beds
2.3 Fertilizers as recommended by local agricultural officer
2.4 Chemicals for killing mealy bugs as recommended by local
agricultural
officer
2.5 Flower inducing chemicals or plant hormones, e.g. NAA, as
recommended
by the local agricultural officer
2.6 Weedicides as recommended by local agricultural officer
1.0
Introduction to the Pineapple
Project
See also 19.2.9.1: Jelly using fresh pineapple and
tinned pineapple
See also 7.4.3: Bromelain enzyme from
pineapples
Bring a pineapple into the classroom.
1. Show a ripe pineapple fruit. Cut it into small pieces and taste it.
2. The scientific name for the pineapple plant is Ananas comosus.
Pineapples
are in the botanical family Bromeliaceae, genus Ananas, species
comosus.
Ananas is modified from the original South American name for the plant
"nana", meaning fragrance. The species name "comosus" means "long
hair".
Pineapples are terrestrial herbs with very short stems bearing rosettes
of long narrow leaves that may have spines. The flowers of the dense
terminal
inflorescence stick together so that a fruit called a syncarp forms.
Above
the inflorescence the main axis keeps growing to form a terminal crown
of leaves. The original pineapples from South Brazil and Paraguay
spread to Central
America and in the 16th century were taken to Asia and Africa by
explorers.
Pineapples were introduced to the Pacific region in the 19th century.
When Christopher Columbus brought the first pineapple to Spain in 1493,
the Spanish thought it resembled a pine cone and called it Pine (pina)
of the Indies. The English called it an apple because of its taste. So
the name "pineapple" is Spanish and English. Commercial production in
order
of amounts grown is as follows: Hawaii, Mexico, Cuba, Puerto Rico,
Brazil,
Nigeria, South Africa, Kenya, Taiwan, Philippines, Malaya, Australia.
3. Pineapples are high in sugar content. When mature the yellow flesh
of the fruit has 10 to 18% sugar and 0.5 to 1.6% acid.
The main food
value
is as a protective food because pineapple contains useful amounts of
vitamins
A, B and C. Pineapples can be eaten as fresh ripe fruit, peeled,
sliced,
cored and put into cans, crushed to make pineapple juice, used in
cooking.
In some areas a pineapple wine is fermented. Pineapples also contain
bromelain,
a protein digesting and milk clotting enzyme similar to pepsin.
Bromelain
is used commercially to tenderize meat and may be good for your
digestion.
4. Add pineapple juice to milk. The milk protein begins to coagulate
and degrade as it reacts with the bromelain. Pineapple juice will also
remove the gelatine emulsion surface on black and white
photographic film!.
5. Pineapples will grow quite well on soils that are not very rich,
but they grow better if given some fertilizers. Pineapple plants can
keep
living through dry times. Tops cut off fruit can be kept alive in the
shade
of a dry room for nearly a year.
6. A moderate rainfall of 1000 to 1500 mm is preferred for best growth,
but pineapples grow well in heavier rainfall conditions, provided the
soil
is well drained and the area frost free. The best environmental
conditions
are cool nights and sunny days.
2.0 Parts of the plant
See diagram 60.2: Pineapple plant parts
The pinapple plant is a herbaceous perennial that grows to 1.5 m high
and 1 m wide with a rosette of leaves around a terminal bud. The leves
are long and pointed. The terminal bud produces a flowering stem thta
becomes an inflorescence of red purple flowers attache dby a leaf like
pointed bract. The pineapple has no seeds because they develop
fruit even if not pollinated and pineapple cannot self-pollinate. Some
wild pineapples do have seeds. The pineapple fruit is a multiple fruit
formed from the fusion of over 100 fruitlets embedded in an
edible stem. The ovary of each flower becomes a berry so all the
berries squash together to form a single structure. he tough waxy skin
contains what remains of the pointed bracts and the flowers.
1. The plant consists of a main shoot and several side shoots. The
main shoot keeps growing straight up. A shoot consists of a shoot apex
or growing part and a stem. The shoot apex, the "growing point", it is
always growing upwards and never dies. The fruit is formed in the stem
when the shoot apex makes a flower bud instead of a leaf bud. In the
angle
between the leaves and the stem are buds called axillary buds. These
buds
may grow out into side shoots, suckers or slips. The lower buds may
grow
into roots.
2. The fruit is coloured yellowish orange when it is ripe.
3. The butt is the main stem or stalk of the plant below the fruit.
4. The top is the small leafy shoot that keeps growing above the fruit
This part makes the best planting material
5. Suckers are large strong shoots, branches, from the main stem or
butt. The suckers come from axillary buds at the lower part of the
butt.
Suckers may not grow at all if the plant has produced too many slips.
6. Slips are small leafy shoot branches that grow up from the upper
part of the main stem or butt. Slips come from axillary buds at the
upper
end of the butt, just underneath the fruit. If the plant has too many
slips,
they take some food that could have gone into the fruit.
7. Roots grow from the bottom of the stem and the butt. Also some roots
may grow from the axillary buds low down on the stem.
3.0 Soils for growing pineapples
1. Pineapples grow well on some Pacific Islands but they will not grow
well on coral soils. Pineapples grow well in the lowlands and in the
highlands
to an altitude of about 1700 metres.
2. They grow best on the slopes of hills if the soils have come from
volcanic, basaltic, rocks.
3. Most pineapple soils are not very rich; in fact most of them are
poor soils that do not contain much plant food so pineapple soils need
fertilizers.
4. Pineapples must have a soil with good drainage If the soil is badly
drained the clay subsoil should be ripped up by tractors to loosen it.
5. The best place to plant pineapples is on a slope of about 40 degrees
If the soil is flat, then the soil should be heaped up to make beds in
line with the direction of maximum slope. Because pineapples do not
cover
the ground well, rain may wash away the good topsoil. To prevent this
erosion occurring, pineapples should be planted only on flat or gently
sloping land.
6. The best soils for pineapples are well drained, slightly acidic
soils pH 4.5 to 5.5 with good drainage, high soil organic matter and
high potassium, K. Pineapples can tolerate high levels of Aluminium, Al3+,
and Manganese, Mn2+. Pineapples are very heavy feeders on
foods
in the soil, particularly nitrogen and potassium. Plants that have been
growing in the same area for a few years commonly have red leaves
because
nitrogen is scarce. Yields will start to decrease and fertilizer must
be
applied to increase the yields again. Plant material applied as a mulch
can also provide food for the crop. If waste material from other crops
is available, this can be spread over the ground as a mulch to keep
down
weed growth, In some countries paper or black plastic is laid on the
ground
to prevent weed growth. Perhaps the best method is to plant the
pineapples
under the shade of another crop, for example bananas, so that the weeds
will be shaded out.
4.0 Leaves
See diagram 60.4: Pineapple leaves
1. The leaf is long, up to 100 cm, and ends in a point. The leaf is
curved upwards on the side facing the stem. The back of the leaf is
rounded.
Two main varieties are the rough leaf variety with spines on the leaves
and produces a good eating fruit, and the smooth leaf variety with
spineless
leaves and larger but not as tasty fruit. Some varieties have smooth
leaves
that contain water storing tissue. Other varieties have spines. You
need
gloves to handle the spiny leaves.
2. Cut across a leaf with a sharp knife to see that the thickness of
the leaf has two parts: (a) dark green food making part, and (b)
lighter
coloured water storing part.
3. Look at a whole plant from the side to see the angle of the leaf
to the stem is greatest with the lower leaves and smallest with the top
leaves
4. Find two leaves in line one above the other. The pineapple leaves
grow very closely together. They are joined in a spiral to the stem.
Usually
every 13th leaf is directly above another leaf lower down. There are
usually
5 spirals between the 2 leaves that are in line.
5. The older leaves of pineapples do not drop off as with many other
plants.
6. Count the total number of leaves on one plant. When the pineapple
plant makes a fruit there are usually from 60 to 80 large leaves formed
7. The largest leaves are usually found at the top of the plant. The
largest and most recent leaf to mature is called the "D leaf". This is
the highest leaf on the plant and it stands nearly straight up.
8. The leaves are made by the shoot apex, growing point. Select a top
that has been cut off a fruit. Use a sharp knife to make a cut straight
down through the middle of the top. Look at half the top to see how the
shoot apex makes the leaves
5.0 Roots
Dig up one plant so the roots can be seen.
1. Most of the roots come from the bottom of the stem or butt. Other
roots often grow from the axillary buds of the lowest leaves. These are
called axillary
roots
2. Pineapple roots usually grow sideways for one to two metres and
grow down about 85 cm.
3. Measure the thickness of some roots.
4. Dig up some roots growing at one side of a plant and see how far
sideways they grow.
5. Dig a small hole straight down to find if there is a hard layer
of subsoil there that might stop the roots going down.
6.0 Flowering and forcing
See diagram 60.6: Pineapple life cycle
1. When the pineapple plant is big enough, the shoot apex makes flower
buds usually when it has 60-80 leaves about 14 months after planting.
The
flower is an inflorescence of 100 to 200 flowers with three fleshy
sepals and petals, six stamens, and the ovary in 3 parts. The fruit is
a
cylindrical,
compound fruit formed by fusion of berry-like fruitlets. The leafy
shoot
at the apex called the crown.
2. The making of the flower buds is called "flower initiation". The
flower buds turn into the fruit that is really a big flower. The fruit
is many individual berries fused to the central stalk. So the "fruit"
has
leaves on top due to the continued growth of the stalk beyond where the
berries are attached.
3. After 4 to 5 months post initiation the fruit is ready.
4. Suckers planted in November to December will start growing about
December
the next year. The fruit will be ready during April to June the next
year
after that.
5. Suckers planted in March to April will initiate in April to June
the following year. The fruit will be ready in September to November.
6. If a field of pineapples can be made to produce a crop
simultaneously
repeated labour harvests are avoided. Growers learned to use ethylene,
acetylene or the plant hormone auxin to bring all plants to flower
together.
The process is called "forcing" or "closing out", or "induction".
Nowadays
the growth regulator ethephon, an ethylene releasing compound, is
sprayed
onto pineapple plants to promote uniform flowering. Pineapple fruits
usually
mature at certain times of the year so that there are times when
pineapples
are not available. By using these ethylene releasing compounds or
flowering
hormones, pineapples can be made to fruit earlier than they would have
naturally. Also it can make all plants in one area fruit together so
that
operations like harvesting and de-suckering can be carried out more
easily.
7. Apply forcing to plants when they look big enough to carry fruit
depending on the type of planting material used and the growing
conditions.
If applied too early, small sized fruit will result. Mix a few drops of
the forcing solution with water then pour into the heart of the plant,
e.g. Fifty drops for half a bucket of water, 4.5 litres is enough for
75
plants. After applying the forcing solution fruit should be ready for
harvesting
from rough leaf pineapples in 22 to 24 weeks, and for smooth leaf
pineapples
in 26 to 30 weeks. Ask the local agriculture officer for help with
forcing.
One recommendation is to use 0.5 Kg Ethephon, 80 Kg urea for
absorption,
Na2CO3 for pH increase to 9.0, 2250 - 3000 litres
water per hectare. Forcing with growth regulators is most effective
during
cooler seasons. Hot weather
is not good for good floral induction. During
hot seasons when night temperatures are greater than 25oC do
not use nitrogen (N) fertilizer for four to six weeks before forcing to
improve flower induction.
7.0 Planning the pineapple garden
See diagram 60.7: Pineapple garden beds | See also 6.9.14
Composting
1. Plant pineapples early in the year where there is a little slope
so that water will run away from the planting material. Pineapples will
not grow well if the soil in that place is too wet, or if there is bad
drainage. The soil on the slope may be a better red volcanic soil. The
slope must not be too steep because rain washing down may cause soil
erosion
and the soil will be lost.
2. Build up beds 60 cm apart and 30 cm high with the plants at least
30 cm apart in the beds. Pineapples can be planted in rows, or
individually.
One system has two rows planted next to each other, 60 cm apart, and
with
30 cm between plants within rows. A distance of 1.8 metres is left
between
the centre of one double row and the centre of the next. If bananas are
also grown and if the spacing between these is about 4 m x 2 m, then
there
is plenty of room to plant double rows of pineapples between the rows
of
bananas. To give 100 students a reasonable sized piece of pineapple
(say
200 gm) once per week, about 800 plants would be required. At the
recommended
spacing, using double rows, this would take an area of about 220 square
metres, 22 m X 10 m. If pineapples are grown under the shade of
bananas,
the area required to give a supply of bananas to 100 students was 30 m
x 20 m. If pineapple were grown in the spaces between these bananas,
there
could be enough room for about 850 plants. Commercial production may
use
rows 60 cm apart within beds and plants 28 cm apart within rows, a
total
of 75,000 plants/Ha for the fresh pineapple market.
3. Before land is used for the next crop all old pineapple plants must
be dug up and burnt because old plants may have diseases or pests, e.g.
mealy bugs.
4. After marking out the pineapple garden area mark the corners of
the plot with stakes. A suitable garden may measure 65 m wide by 10 m
long.
This would give us enough room to have five rows each about 10 m long
After
marking out the area, dig the area and form it up into
separate gardens. Pull out all the weeds. New land must be well cleared
then dug to a depth of 30 cm and any leaves or grass left to rot. The
crop
does not cover the ground well so the soil is exposed to the sun and
weed
growth can be vigorous. Weeds must be controlled so that a good crop
can
be obtained. Weeding with a hoe or a grass knife is the usual method.
Chemicals
that kill the weeds but do not affect the pineapples can be used, e.g.
Diuron, dissolved in water.
5. Sprinkle some mixed fertilizer over the soil on the beds A
fertilizer
mixture that contained nitrogen, phosphorus, potash, magnesium and some
zinc and iron can be used. After mixing the fertilizer well, spread
over
the soil at the rate of about 150 gm per square metre of bed. Also
spread
some insecticide, e.g. heptachlor, over the soil to kill mealy bugs.
Take
great care to avoid getting any of this chemical on their hands. Ask
your
agriculture department officer to show you how this must be done.
8.0 Types of planting material
See diagram 60.8:
Pineapple plant
1. Commercial pineapples are not grown from seed. Commercial cultivars
from Hawaii
and the West Indies are self-sterile. The tiny flowers cannot be
fertilized.
Pineapples are reproduced by vegetative propagation, using crowns,
slips, or suckers. The 5 types of planting material used are as
follows:
2. Tops or crown is the leafy vegetative shoot that grows on the top
of the fruit. Plants that grow from tops take longer to fruit than
those
grown from suckers and slips. They are the best kinds of planting
material,
especially if they are large and come from a plant that had a big
fruit.
Planted year round they 2 years to produce fruit or can be forced 9
to 13 months later. Plant crop duration is 15 to 20 months in cooler
areas
and 11 to 14 months in warmer tropical areas
3. Aerial suckers are leafy branches carried on the stem above ground
level. Plants grown from aerial suckers produce fruit more quickly than
other sorts of planting material, and yield lots more fruit.
4. Suckers or ground suckers are leafy branches or side shoots that
arise from axillary buds of the leaves on the stem at or below ground
level. Suckers
are very good planting material. They are usually the heaviest kinds of
planting material, and may weigh as much as 1 kg each. They grow faster
and may make a fruit after 18 months. They can make a second crop or
ratoon
crop of fruit. However suckers may not grow very strongly if there are
many slips because slips take all the food from the leaves. Plants may
have 6 to 12 slips but plants with many slips will not sucker until the
slips are removed. Some plants never make any suckers. Suckers take 17
months to produce fruit.
5. Slips are the leafy side shoots carried on the fruit stalk that come
from axillary buds just below
the fruit. It is good if there are no more than four slips on each
plant,
and best if there are only two slips. If there are too many slips on a
plant, it is best to break them all off using a forked stick. Also, cut
the growing point or shoot apex so that this plant can never be used to
supply planting material. If it were used, the new plants would also
make
too many slips. Plants from slips take 20 months to produce fruit.
6. The butt is part of the stem below the fruit. This can be used as
planting material, but it grows very slowly and is not often used.
Butts
or ratoons are the stems of the plants that can be used for planting
after the
fruit
is harvested. The base of the stem and the fruit stalk are cut away and
the leaves are removed. Plants grown from butts are very slow to
produce
fruit and do not yield very well.
Propagation is by crowns and slips for commercial production and ground
suckers and suckers for non-commercial production. All this material
needs
to be prepared for planting by stripping off the leaves at the base to
allow it to dry in the sun for a few days to help a vigorous root
system
get established
9.0 Selecting plants for planting material
1. If the best plants are used for planting material, the plants will
produce bigger fruit for better prices.
2. The food made by photosynthesis in the leaves goes up the stem to
be used to make the fruit, slips and suckers. Plants that make the best
pineapples have a big fruit and no more than two slips. Poor plants
have
six to seven slips and may not make any suckers. So do not take
planting
material from plants that have four or more slips to each plant because
they will grow into poor plants where most of the food goes into making
the slips, and not into the making of fruit and suckers.
3. Look at many pineapple plants to find (a) some plants with only
two or three slips and (b) plants with many slips. Find any suckers on
these plants.
4. Select plants that make strong suckers quickly because these will
grow into a strong following crop. Good planting material comes from a
healthy plant with big well formed fruit. The plant should have only
two
or three slips. Tops are the best planting material because they are
nearly
always the same size so they grow evenly and make fruit simultaneously.
The next best are big slips especially if the plan has few of them.
Planting
material should all be about the same size and weight otherwise the
fruit
will ripen at different times so you cannot send it away to be sold
because
some fruits are not ripe. Also if you use a hormone to make the plants
form a fruit some plants will be too small and the fruit will be too
small
to be sold.
10.0 Planting
1. Before planting break off a few leaves from the bottom of the
planting
material and leave it in the shade for a few days. Dig the surface of
the
garden lightly. Lay out the planting material on the ground and check
that
each bed has only one kind of planting material in it. Plant different
kinds of planting material in different beds to see the difference in
the
way they grow.
2. All the planting material in any one bed should be about the same
weight. Discard and burn any poor planting material.
3. After planting, the soil must be pushed down firmly around each
planting piece. Water the planted pieces.
11.0 Pineapple growing
See diagram 60.11:
Pineapple fruit
1. After planting the stem grows up and the growing point, or shoot
apex, makes new leaves.
2. When the shoot apex has 60 to 80 leaves it then makes a flower bud
This is called "flower initiation".
3. The flower becomes a small pineapple fruit that grows bigger. After
four months the fruit is ready to pick.
4. The shoot apex at the top of the fruit then keeps on growing and
makes the "top". Axillary buds in the leaves growing from the butt turn
into "slips" (high up) or "suckers" (low down). When the fruit is still
forming, use a forked stick to break off all the slips on plants with
more
than two or three slips.
5. Time to maturity differs with different planting materials. The
difference in the time taken for the fruit to be set and mature is that
plants grown from aerial suckers produce first, then ground suckers,
then
slips, then tops, with butts taking the longest. A crop from aerial
suckers
will produce fruit in a year.
6. Harvest as shell colour changes from green to yellow at base.
Pineapples
are non-climacteric fruits because they do not ripen after harvest.
Pineapple
fruit quality is at its best only if the fruit matures on the plant.
They
do not become sweeter if harvested earlier since there are no starch
reserves
to be converted to sugar. The sugar content must come from the rest of
the plant. Pineapples do not store well and should be eaten soon after
harvesting.
12.0 Keeping records
See also 6.9.20.0:
Understanding the records
Keep the following records:
1. Date of making garden
2. Date of planting pineapples
3. Height of plants each month and number of leaves made
4. The number of months when the plant seems to have made a
flower/fruit
bud.
5. The number of months for the flower bud to turn into a ripe fruit
ready to pick.
6. The number of months before the first slip is made
7. The number of months before the first sucker is made.
8. Rainfall during the project.
9. Cost of items bought for the pineapple project.
13.0 Fertilizers
1. The most important plant foods are nitrogen, N, phosphorus, P, and
potassium, K, so a mixed fertilizer should contain these substances
However,
it should also include other elements, e.g. zinc, Zn, and iron, Fe.
Fertilizers
must be applied at the following times:
(a) Before planting - a mixed fertilizer
(b) 3 weeks after planting - ammonium sulfate spread down the middle
of the bed between the planting materials
(c) 7 weeks after planting - a mixed fertilizer containing urea, iron
sulfate, zinc sulfate At this time some Diazinon should also be spread
on the soil to stop mealy bugs.
(d) 12 weeks after planting - a mixed fertilizer NPK 10-1 -15
(e) 20 weeks after planting - same as for 7 weeks
(f) 30 weeks after planting - same as for 7 weeks
(g) 37 weeks after planting - a mixed fertilizer NPK 10- 1 - 15
(h) 44 weeks after planting - Ammonium sulfate only
(I) 48 weeks after planting - mixed fertilizer NPK 10-1 -15
2. Ask an agricultural officer how much of these fertilizers to put
on the soil each time. If fertilizer is to be added, a mixture high in
nitrogen and potassium should be used. Four bags of urea (200 kg) and
two
bags of muriate of potash (100 kg) would be an economic amount for a
hectare
of plants in a year. For 500 square metres, 10 kg of urea and 5 kg of
muriate
of potash would be sufficient. This amount should be applied in three
or
four applications throughout the year.
14.0 Pests of
pineapples
See diagram 60.14: Pineapple pests
1. Ask your agricultural officer to help you decide what chemicals
to use and how to use it. Be very careful if children handle these
chemicals
as they are poisonous. Dig up and burn all old pineapple plants at
least
six months before planting new material Treat the soil with a chemical
like Diazinon before planting pineapples Treat all planting material
with
recommended chemicals before it is planted. Treat the soil around the
growing
crop with chemicals to kill the bugs. Some bugs may live at the base of
the leaves, but spraying the leaves does not stop the disease because
most
of the bugs are under the ground.
2. The Mealy bug (Dysmicoccus brevipes) causes mealy bug wilt,
the most serious disease of pineapple. However mealy bugs are
"ant-attended",
so using a recommended insecticide to kill the ants helps control the
Mealybug.
All crowns, suckers and the like could be treated with Malathion or
diazinon
and let dry before planting. The Mealybug is a small white insect that
can often be seen on the fruit or at the base of the leaves. This small
animal lives mostly under the ground and feeds on the roots. It carries
a disease called mealybug wilt virus that infects the pineapple roots.
This makes the roots stop growing, become soft and then rot. If they
are
a problem in a particular area, planting material should be dipped in a
solution of Malathion, e.g. Add 25 mL Malathion 50% Miscible
Oil to 10
L of Water.
3. Pineapple wilt disease, caused by a fungus, can be treated in the
same way as mealy bug. If you look at the roots and you cannot see any
mealy bugs. However, if the roots are rotten, then it may be the root
rot
disease caused by the fungus. It only grows in soils that do not have
good
drainage so doing anything to stop this disease may not be possible
until
the ground is cleared for the next crop Then either give the soil
better
drainage or leave this soil and move the garden to a better
place.
15.0 Weeds
1. Weeds are any plants that are growing where you do not want them
to grow Weeds have the following bad effects on pineapples:
(a) They take soil water from the pineapples.
(b) They steal plant food from the pineapples. If you put some
fertilizers
on the soil, some of these plant foods will be used by the weeds.
(c) Weeds may also take light away from the pineapples by shading them.
(d) Sometimes strong growing weeds may take living space from
pineapples.
2. You can kill weeds by:
(a) Digging them out by hand This can be done in a small garden, but
cannot be done if many pine apples are being grown.
3. Some weedicides can kill grown weeds Others are called pre-emergent
weedicides because they kill the weeds when they have only just come
through
the soil. Weedicides like Bromacil, Ametryne and Diuron are
pre-emergent
weedicides.
16.0 Improving pineapple production
1. At the end of the project it is a good time to think of how
production
of pineapples could be improved, e.g. better selection of good planting
material because far too many poor plants are growing, too many mealy
bugs,
too many weeds growing, not enough fertilizers used. A very common
mistake
in pineapple growing is to leave the plants growing in the same
position
for many years. After a plant has produced a fruit, it will not produce
another one. Instead, one or more of the sucker plants that grow out
from
the mother plant will carry a fruit. If all the suckers are left on the
other plant, small fruit will be produced.
2. After a fruit has been harvested the mother plant must be cut off
and only one sucker left. The other suckers must be removed and soil
heaped
around the base of the remaining sucker so that the roots can obtain
food
easily from the soil. This is called ratooning and will produce a
ratoon
crop. Each plant propagated produces one fruit at the top of its stem.
This high quality fruit is called the plant's crop. After the fruit is
harvested, several suckers develop and one year later produces the
ratoon
crop. The fruits are smaller and of lesser quality. A second ratoon
crop
can develop after the first crop is harvested. After that, the field is
dug up and replanted. When this has been done twice, that is when three
fruits have been harvested from one planting, it is best to remove the
crop and replant. This is because the fruit becomes smaller with each
ratoon
crop. Large fruit will be obtained again after replanting.
3. It is best to plant the new crop on new ground and plant a different
crop on the old area, or allow it to rest for a few years. This helps
to
prevent a build up of weeds, insect pests and diseases in the area.
Planting
can be done at any time of the year provided sufficient planting
material
is available and the soil is not too dry.
History
These teaching materials were originally written and illustrated by
Mr J. A. Sutherland, Faculty of Education, University of New England,
Armidale,
Australia and later edited by Dr J. Elfick, School of Education,
University
of Queensland, Brisbane, Australia.