School Science Lessons
Pineapple Project
2012-05-12 SPwp
Please send comments to: J.Elfick@uq.edu.au
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
13.1 Boron deficiency
14.0 Pests and diseases 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 19.2.9.1: Jelly using fresh pineapple
and tinned pineapple
See 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 pineapple 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 leaves are long
and pointed. The terminal bud produces a flowering stem that becomes an inflorescence
of red purple flowers attached by 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:
2.1 the dark green food-making part, and
2.2 the 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 to 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, 2 250 to 3 000 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 | 9.14.0
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 × 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 × 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 ×
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 the following:
3.1 some plants with only two or three slips and,
3.2 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 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:
1.1 Before planting, mixed fertilizer
1.2 3 weeks after planting, ammonium sulfate spread down the middle of the
bed between the planting materials
1.3 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.
1.4 12 weeks after planting, a mixed fertilizer, NPK 10-1-15
1.5 20 weeks after planting, same as for 7 weeks
1.6 30 weeks after planting, same as for 7 weeks
1.7 37 weeks after planting, a mixed fertilizer NPK 10-1-15
1.8 44 weeks after planting, ammonium sulfate only
1.9 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 m2, 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.
13.1 Boron deficiency
See 6.9.15.4: Boron deficiency
Boron deficiency in pineapple, causes fruitlets to separate and the gaps
between them become corky. Root growth is poor but only when the deficiency
is severe does the growing point die or the leaves show symptoms.
14.0 Pests and diseases
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. Phytophthora causes top
and root rot of pineapple
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:
1.1 They take soil water from the pineapples.
1.2 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.
1.3 Weeds may also take light away from the pineapples by shading them.
1.4 Sometimes strong growing weeds may take living space from pineapples.
2. You can kill weeds by digging them out by hand This can be done in a small
garden, but cannot be done if many pineapples 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.