Pineapples (Ananas comosus)

  1. Introduction

Pineapple is an herbaceous perennial plant in the family Bromeliaceae. It is native to South America, but is currently grown throughout the tropics and in warm subtropics. It grows to a height of 1.0 m – 1.5 m with 30 or more trough-shaped and pointed leaves (30 cm – 100 cm long), surrounding a thick stem. The fruit has high sugar content and is rich in vitamins A. Fresh pineapples is an excellent source of anti-oxidant vitamin C and also rich in B-complex group of vitamins like Folates, Thiamine, Pyridoxine, Riboflavin and minerals like copper manganese and potassium.

Plate 15.1 Pineapple field and Pineapple fruit

  1. Varieties

Table 15.1: Pineapple Varieties

Variety Description Remarks
Smooth Cayenne The fruit is pale yellow to yellow The fruits have a high sugar
flesh, cylindrical in shape. and acid content
Leaves are dark green with It is grown commercially for
purple patches along the base both canning and the fresh
of the upper surface and do not market
have spines along the margin. It produces 2 – 3 suckers
The fruit weighs 2 – 6 Kg
Variety Description Remarks
Hilo It is a variant of ‘Smooth Cayenne’ It produces no slips but
The plant is more compact and numerous suckers
the fruit is smaller and more
cylindrical.
The fruit weighs from 1.1 – 1.5 kg
It has a very small crown.
Giant Kew The variety bears a large fruit The core is large and its
averaging 2.75 kg – 4.5 kg. extraction results in too large
a hole in canned slices.
Monte Lirio Have smooth leaves with
no terminal pine. The fruit is
rounded, white-fleshed, with
good  aroma and flavor.
Red Spanish The plant is very spiny The fruit is fair for canning.
The fruit is more or less round It is highly resistant to
fruit rot though subject to
in shape, orange-red externally gummosis.
with deep eyes. The flesh is pale- The fruit  is  hard  when
yellow, fibrous, with a large core mature and breaks off easily
aromatic and flavorful at the base during harvesting
Fruits stand handling and
transport well.
Queen The fruit is conical, deep-yellow, The plant is dwarf, compact,
with deep eyes and weighs 0.45 cold and disease resistant
-1.13 kg; than ‘Smooth Cayenne’
It is less fibrous than ‘Smooth The plant matures early, it
Cayenne’ but more fragrant; it is is low yielding and suckers
juicy, of fine flavor with a small, freely hence requires
tender core. thinning.
It is sold fresh and keeps well.
lt is fair for canning because
of its shape which  results in
much waste
  1. Ecological Requirements

Altitude

Pineapples grow from 0 – 1600 m a.s.l. Altitude has an important effect on the flavour of the fruit; above 1800 m they become increasingly sour and acidic while below 1,350 m they are marshy and sweet. For canning, the recommended altitude should be be-low 1,350 m.

Temperature

A temperature range of 18 0C – 30 0C is favourable and 25 0C is optimal. The plant can tolerate cool nights for short periods. Prolonged low temperatures retards growth, delays maturity and cause the fruit to be more acidic. Temperatures below 20 0C can lead to chlorotic discolouring. The right combination of heat and moisture are important factors to consider for successful pineapple production.

Rainfall

Pineapple will produce fruit under annual precipitation of 650 mm – 3,800 mm depending on cultivar, location and atmospheric humidity (it should range between 70

  • and 80 %). Ideal rainfall for pineapple production is about 1,100 mm. Reasonable yields can be obtained with as little as 750 mm of well-distributed annual rainfall or with supplementary irrigation.

Soils

The best soil for pineapple growing is a well-drained, sandy loam with a high content of organic matter and should be friable for a depth of at least 60cm. Pineapples cannot stand water logging. The crop does well on soil of pH of 4.5 – 6.5. Soils with old anthills have a higher pH, and are not suitable for the production of good pineapples as it reduces the yields. Avoid black cotton soil, low lying areas and common red loams that are likely to flood.

  1. Agronomic practices

Land preparation

  • The land should be well prepared by deep ploughing before planting because the pineapple is shallow-rooted and easily damaged by post-planting cultivation.
  • Plough to a depth of 45 cm
  • Deep ploughing ensures proper root development and penetration and control of perennial weeds. Perennial weeds may also be eliminated by chemical control
  • After ploughing, harrow to obtain fine tilth.
  • In areas where the soils have high clay content, it is essential to plough also during the dry season to facilitate root penetration.
  • For land previously under pineapples, small-scale growers can uproot old pineapple plants by hand, while large-scale growers can use a large harrow to uproot and chop the stumps and leaves.

Fumigation

Soil fumigation is recommended for land under continuous cultivation of pineapples without a fallow period. Use recommended fumigants such as Basamid granular and Nemasol.

Propagation and planting

Commercial propagation of pineapple is vegetative. The planting materials should be from newly harvested field. Three types of planting material are used for vegetative propagation:

  • Crowns are the leafy growth on top of the fruit. They take long to come into bearing (25 – 28 months) and rot easily, but the growth is uniform and less susceptible to premature fruiting.
  • Slips are leafy shoot growth arising from the fruit stalks. They are graded according to size for growth uniformity. They ripen very unevenly and also take long to come into bearing (22 – 24 months).
  • Suckers are leafy shoot growth from the base of the plant where the roots grow (stem auxial buds). They give the highest yield, and have long harvest duration. They are more difficult to plant. Suckers take 18 – 22 months to come into bearing. Suckers of 600 g are too big and should not be used as they are too old and tend to flower early.

Plate 15.2: Pineapple planting material

Rapid multiplication

If there is shortage of planting material, each type of planting material can be split vertically into two or four sections each with a bit of root section and planted into irrigated nurseries at very close spacing. They can then produce new plantlets in 3 – 4 months.

To avoid infection by dry-rot fungus, all the shoots should be stored in a shady place for wounds to heal and suberize quickly. Care should be taken to ensure that no mealy bugs are present in the shoots or on the leaf blades by dipping the planting material into a mixture that contains recommended insecticide e.g. Nemacur 400EC. No soil should remain on the shoots to prevent an infection by soil-borne fungus such as Phytophtora spp. and/or nematodes.

Control of infection in planting material

Immerse planting material in hot water at 50°C for 20 minutes to control mealy bugs, phytophtora and nematodes. After this treatment it is important to drip-dry the planting material to avoid fungus attack and deterioration. The planting materials are spread thinly on the ground to avoid over-heating and rotting. Allow the chemical to dry on the seed.

Planting

Planting is normally done at the beginning of the long rains. Strip off the basal leaves of the material just prior to planting to expose the adventitious roots facilitating good con-tact between the plant and the soil. Leave the planting material exposed to the soil, if the planting material arrives well in advance of the intended planting date. Stack the material upside down and cover with thin layer of grass. Slips and suckers may be planted to a depth of 10 cm -15 cm without adverse effects.

Spacing

Spacing depends on cropping pattern chosen.

  • For mono-cropping where irrigation is available, a plant population of 70,000 plants to 100,000 plants/ha is possible. This can be achieved by planting double rows 40 cm apart, 60 cm between the double rows, and 20 cm between plants. This can give a yield of 100 tons to 120 tons/ha plus about 40 tons/ha for the ratoon crop.
  • Under rain fed conditions, spacing between double rows is increased to 60 cm apart and 90 cm between the double rows and 30 cm between plants. This spacing can yield about 75 tons/ha plus 30 tons/ha in the first ratoon.
  • In intercropping, the same double rows can be used and interplanted with legumes and/or cereals. The intercropped area and the pineapple area can then switch location when pineapples are replanted.

Mulching

Use of black polythene 150 gauge is recommended to conserve soil heat, retain moisture, improve fumigation and control weeds. In hot areas, use of mulch may not be essential. Use of grass mulch should be avoided as it may reduce yields since it does not maintain the desired soil temperature.

Fertilizer and manure

Soil nutrient analysis should be done to determine the levels. Where soils are depleted, the following can be applied:

  • 300 Kg of DAP 10 cm deep below the planting line in a furrow before mulching, or as a side dressing treatment at 11 g/plant when plants are about 2 months old. The fertilizer is placed at the base of the plant to avoid scorching.
  • 5 tons -10 tons/ha of manure can also be applied to the field 10 cm deep below the planting line in a furrow before mulching and planting.
  • Fertilizer is mainly used in large plantations. Application is as shown below
  • 850 Kg/ha of NPK and 750 Kg Sulphate of Ammonia (SA) after 6 months
  • 750 Kg/ha of SA (Sulphate of Ammonia) is applied 3 months after first harvest and 720 Kg/ha of SA 3 months later.
  • A general application of 100 Kg – 250Kg/ cre of rock phosphate should be added at the same time.
  • Each ratoon crop will again need a new supply of nutrients and will benefit from compost as well as rock phosphate at the same rate.
  • If legumes are used as green cover plants, it should be considered that they supply significant amounts of nitrogen to the soil when calculating the amounts of compost required. In this case, compost with a rather high Calcium/Nitrogen ratio should be used. If possible, the compost should be spread in two separate lots: one half (2.5 tons) before planting, and 2.5 tons to induce flower formation.
  • Organic foliar feed is also beneficial. However, too much nitrogen will result in watery/ glassy fruit as well as in production of multiple crowns on fruits and too many slips.
  • Deficits in the potassium supply can be balanced out by the use of wood ash (combined with compost).
  • In exceptional cases, the certification bodies will allow the use of Potassium magnesia in organic farming.
  • No fertilizer should be applied after the first bud stage

Irrigation

Irrigation is essential right after planting unless this is done during the rainy season. The field is watered thoroughly to initiate root establishment on the materials. After establishment, irrigation is only necessary when long dry periods occur. Overhead or drip irrigation is recommended while flood irrigation should be avoided.

The excess water should be drained to avoid pathogens infestation and increase aeration.

Flower induction

  • Pineapple flowering may be delayed or uneven, and it is highly desirable to attain uniform maturity and also to control the time of harvest in order to avoid overproduction in the peak periods.
  • Synchronized flowering can be induced by smoke (due to ethylene produced). Ethylene and ethylene-releasing compounds (e.g. Calcium carbide) used in conventional production are very effective.
  • Flower formation in agro forestry systems can be induced by selective tilling of the weeds and by cutting back trees two months before the time blossoming is supposed to occur.
  • The sudden increase of light will have a similar effect to using carbide. This enables the harvesting time to be controlled in response to market demand (e.g. before or after the usual regional harvesting season to gain a price advantage).

Weed control

Spot spraying methods are used where there are weeds. Light hoes/Jembes are also used. Chemicals such as round-up are used to control couch grass. Use of black polythene is also recommended.

Plate 15.3: Pineapple growing cycle

  1. Pests and Diseases

Table 15.2: Pests

Pests Symptoms Control
Thrips Thrips are considered important Controlling weeds that
(Thrips tabaci) pests of pineapples because they are habour thrips in the early
and Blossom vectors of the yellow spot virus, which stages.
or Cotton have been shown to be identical to Thrips are attacked
bud thrips the tomato spotted wilt virus. by predatory thrips,
(Frankliniella The blossom thrips feeds mainly on lacewings and predatory
schultzei) bugs.
flowers and its feeding results in the
Avoid use of pesticides
development of “dead-eye” in the
that kill natural enemies.
fruit.
Thrips feeding on the crown of fruits
results in concentric ring patterns
developing on crown leaves.
Pests Symptoms Control
Pineapple •   The mealy bugs are oval, pink in Control ants to give a
mealybug colour and up to 3 mm long. chance to natural enemies
(Dysmicocos •   They are covered with a whitish to keep mealy bugs under
brevipes) waxy secretion, which develops control.
into waxy filaments around the Drench planting material
body.
Pineapple •   Mealy bugs are sedentary insects, in recommended
which are moved from plant to insecticide
mealybug plant by attendant ants. Nemacur 400EC Regular
(Dysmicocos •   They are found at the base of
brevipes) leaves, moving on to healthy plants rogueing of affected
once their host starts to wilt. plants should be done.
Warm weather favours the build-up Use clean planting
of mealy bugs.
•   Infestation cause discoloration of material
bronze to red or pink with margin
bent abruptly backwards.
•   The mealy bugs feed in the floral
cavities, on both small and mature
fruit, and on the crown leaves.
•   Heavy infestations are conspicuous
because of the white waxy adults,
which often occur at the growing
points, around the stem nodes, on
the undersides of leaves, on the
fruit and on the roots.
Feeding on leaves causes yellowing
and drying up of the leaf-tips,
which progresses towards the base
of the leaves.
•   Feeding in the blossom cavities
causes wounds, which sometimes
become contaminated by fungal
spores resulting in a disorder called
black spot. Feeding on roots is
associated with the rotting of roots
and subsequent wilting of the
plant.
Nematodes Root-knot nematodes (Meloidogyne Practice crop rotation.
(Meloidogyne javanica) cause distinct swellings Allow extended fallow.
javanica and (galls/knots) on the roots. The root Use recommended soil
Pratylenchus lesion nematodes (Pratylenchus fumigants Basamid
brachyurus) brachyurus) develop brown lesions granular Nemacur 400EC,
(spots) on the roots, which may girdle
the roots and cause their premature
death.

Table 15.3: Diseases

Diseases Symptoms Control
White leaf spot The fungus causes white leaf spot, Choose sets with at least
(Ceratocystis black rot, base or but rot and soft three nodes to increase the
paradoxa/ rot or water blisters. likelihood that the buds
Thielaviopsis White leaf spots are yellow to towards the centre will
paradoxa) germinate before the fungus
brown measuring between 2.5 cm invades all the tissues.
to 5.0 cm long on the leaves. They In disease prone areas,
later dry to become papery and planting material should be
straw coloured. treated in hot water (50°C for
Base or but rot is a common 20 minutes)
Avoid extremely wet or dry
disease of crowns, slips and soil conditions.
suckers used for establishing new Do not plant freshly cut
plantings. pineapples unless dried out.
Rot of planting material occurs To prevent the spread of the
when they are not dried and are pathogen, avoid wounds to
packed with little aeration. tissue and remove infected
The fungus also destroys older plants. Improve soil drainage
plants by entering through injuries and avoid planting during
during weeding or other field wet weather.
operations.
In severe conditions the entire
plant may turn dark and rot within
2-3 days
Black rot is a post-harvest disease
occurring on injured fruit, and a
soft black rot with dark colored
mycelium develops.
Water blisters consist of a soft,
watery rot of the fruit flesh  with
overlying skin glassy, water-soaked
and brittle. Eventually, the skin,
flesh and core disintegrate and the
fruit dries out, leaving an empty
fruit carcass containing a few, black
vascular fibres.
The fungus enters the fruit through
wounds and the crevices between
individual fruits.

 

Diseases Symptoms Control
Pineapple wilt Infected plants turn yellowish-red Use planting material from
virus to bright red at the leaf tips. wilt-free areas. Control mealy
This colouration spreads down the bugs.
leaf with time and shows signs of
wilting; however the inner heart- Heat treatment of pineapple
leaves remain normal. Severely crowns in a large water bath
infected plants become stunted at 50°C for 20 minutes
and produce small, undergrade Crop planted on virgin
and immature fruits. land or well-fertilized soils
The first effect of the disease (especially rich in nitrogen)
appears on the roots which appear to be more resistant
stop growing, collapse then rot to wilt.
resulting in symptoms similar to
the effect of drought. Avoid adverse growing
The root system collapses and conditions which increase
rots before the first leaf symptoms the susceptibility of plants to
appear. wilt.
Younger plants stand a better
chance of recovery
Older plants are less
susceptible than younger
plants
Slips and suckers are less
susceptible than the mother
plant on which they are
borne.
Watery The fruit becomes completely Avoid applying nitrogenous
pineapples watery. The cause is mainly fertilizer when the plants
physiological and is associated have started to bear fruit.
with excessive late nitrogen
application.
Multiple crown The smooth Cayenne normally To minimize occurrence,
has one crown on a fruit but select suckers from single
occasionally more arise. High crowns only.
rainfall plus excessive Nitrogen
application favour this condition.
Diseases Symptoms Control
Yellow spot The yellow spot virus has been Avoid planting near host
virus shown to be identical to the plants of the virus e.g.
tomato spotted wilt virus. Thrips tobacco, egg plant.
are vectors of this virus. It infects
over a 100 species of plants Control weeds in and around
including peppers, tobacco, pineapple fields to reduce
eggplant, broad bean, spinach and the thrips population.
peas.
A number of wild plants, such as Destroy infected fruits
the black jack (Bidens pilosa), Emilia showing early symptoms to
sonchifolia and Datura stramonium, prevent spread
are also host of this virus.
The fruit shows a blackened, dry
cavity in the side of the fruit due
to one or more “eyes” having died.
This is known as “dead eye”.
Infection of very young fruit results
in an irregular arrangement of
fruit-lets as some fail to develop.
Attacked fruits may also fail to
develop a crown.
Thrips feeding on the crown of
fruits results in concentric ring
patterns developing on crown
leaves.
These spots enlarge and the
infection spreads into the fruit
itself, by which time the crown will
often have dried out.
The flesh of fruits thus infected will
be discolored and necrotic below
the butt of the crown.
The whole fruit may eventually
become affected.
  1. Harvesting

It takes 18 – 24 months to get the first crop. A basal golden yellow coloration at the base is the sign of a ripe fruit. The fruits are ready to harvest when they snap off at the bending of the fruit. Fresh fruits destined for the local market are plucked when almost ripe. Fresh pineapples destined for export are harvested green-ripe (beginning to turn yellow-green at the base of the fruit). They are cut off with a sharp knife leaving a stem which is later trimmed to 3 cm – 4 cm. The cut should be horizontal to avoid bruising.

Yields

The crop can yield up to 100 tons – 120 tons/ha and 40 tons/ha for the ratoon crop

Post harvest management

Fruits can be stored for up to 4 weeks at a temperature of about 7 0C. Because of their low sugar-content, pineapples harvested too early are unpopular amongst consumers (unripe pineapples do not ripen after harvest). The colour of the skin is an important criterion in determining the ripeness of the fruit. Fruits destined for the European market are often classified according to the extent to which an orange-yellow colouring has spread up from the base of the fruit as follows:

Ripeness-colour 1: Only the base is orange-yellow.

Ripeness-colour 2: The orange- yellow colour covers half of the fruit. Only ripeness – colour 1 can be exported.

Care should be taken to prevent bruising of fruits. Pineapples intended for canning should have a sugar/acid ratio of 130 to 160 Brix and the fruit is graded according to size. This is only attainable when the fruits mature with plenty of sunshine. The graded sizes are measured on the diameter of the fruit as follows:

Grade I – 12.7 cm minimum diameter and 15.3 cm minimum length (about 3 ½ Kg fruit)

Grade II – 10.8 cm minimum diameter and 13.3 cm minimum length (2 ½ – 3 Kg fruit)

Grade III – 8.9 cm minimum diameter and 11.4 cm minimum length (1 ½ – 2 Kg fruit)

Canneries accept only grade I and II.

Management of crop after harvesting

De-suckering

Once the fruit has been harvested, remove all suckers from the mother plant and leave only one sucker for the ratoon crop. Leaving more suckers will reduce the size of the fruits.

Stripping

Removing slips from the mother plant. By doing this, planting materials are obtained and competition is reduced.

The rest of the slips and suckers can be used as additional planting material after sorting or can be chopped and used as mulch. The mother plant can also be left in the field as mulch.

Ratoon crop

The yields of ratoon crops are much lower than that of the planted crop; however one ratoon crop is economical. A second and third ratoon crop is possible under small scale conditions where the crop is interplanted with other crops, and fertilized well. Once this crop is harvested, all plants need to be dug up and the land prepared for rotational crops. A rotation programme should be followed allowing several years before pineapples are grown on the same land again. Root knot nematode contributes to large crop losses, there-fore to achieve some degree of control; land should be left fallow and free of weeds for at least 6 months.

Some crops usually included in rotation with pineapples are groundnuts, beans, rice and vegetables. To prepare the land used for pineapple production, green manure plants such as cowpea can be grown and incorporated into the soil prior to planting pineapples.

  1. Utilization
    • The fruit is eaten fresh, as dessert and in salads.
  • It is also processed into juice, jam, dried fruits and preserves (crystallized and glace fruit),
  • It is cooked in pies, cakes, puddings; or used in sauces.
  • Canned as slices and spirals.
  • The by-products of canning can be used as cattle feed, to produce pineapple wine or vinegar.
  1. Marketing

There is a ready market for fresh and processed pineapples. The crop grown by the small scale farmers is usually sold locally, while the crop under large scale production is processed and sold either locally or exported.