FARMER'S BOOKSHELF

Information system of tropical crops in Hawaii
Department of Tropical Plant & Soil Sciences
University of Hawaii at Manoa



Pineapple

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Other Links

Ananas comosus. Purdue University
Pineapple. California Rare Fruit Growers, Inc.
Pineapple. Texas A&M University


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Cultural Practice


Pineapple is one of the most extensively researched tropical fruit crops. Many aspects of production have been mechanized, and commercial cultural practices are highly refined.


SOIL PREPARATION. Soil should be well tilled. Addition of animal manures improves tilth, increases soil potassium, and may improve micronutrient availability. If the soil is imperfectly drained, beds at least 20 cm (8 inches) high should be formed.

If nematodes are present in the soil, it should be sterilized, fumigated, or treated with a nematicide.


PLANT POPULATION. Field plantings of pineapple are usually in double-row beds. A population of approximately 58,700 plants/ha will result from beds 122 cm from center to center, rows 55 to 60 cm apart within beds, and plants 28 cm apart within rows.

Plantings for fresh fruit rather than canning fruit may reach 75,000 plants/ha, because smaller fruit is desirable. Within normal field population ranges, fruit size decreases about 45 g for each population increase of 2470 plants/ha.


MULCHING. Black polyethylene approximately 90 cm wide is used as mulch in most commercial plantings in Hawaii. As the mulch is rolled out on the planting bed, its edges are covered with soil. Planting holes are punched through the plastic with a trowel.

When nematicides are injected into the soil, plastic mulch makes them more effective by slowing their dissipation. The mulch increases soil temperature in the root zone, helps to conserve soil moisture, promotes rooting by concentrating moisture in the root zone, and controls weeds. Mulches are not used in equatorial climates with high temperatures and rainfall.


Description


Family: Bromeliaceae
Scientific Name: Ananas comosus L. (Merr.)
Origin: American tropics


Pineapple is a perennial herb 50 to 100 cm high. It has narrow, tapering, pointed leaves up to 100 cm long arranged in a spiral rosette, crowded on and tightly clasping a central stem. Leaf margins are usually but not always spiny.


INFLORESCENCE. The inflorescence consists of 100 to 200 flowers arranged in a compact spiral cluster. The flowers are perfect, with a floral bract, three short fleshy sepals and petals, six stamens, and an inferior ovary with three locules.


FRUIT. The fruit is a terminal, cylindrical, compound structure at the apex of the stem and is formed by the fusion of the berrylike fruitlets that develop from the flowers. At its apex, the fruit bears a compressed, leafy shoot called a crown. The typically yellow fruit flesh is best eaten when sweet and moderately acid; it may contain from 10 to 18 percent sugar and from 0.5 to 1.6 percent titratable acidity.

Commercial clones are self-sterile but cross easily with plants outside their varietal group.


Diseases


Heart and root rot (Phytophthora cinnamomi)

Heart rot (P. parasitica)

Root rot (Pythium spp.)

Black rot (Ceratocystis paradoxa)

Butt rot (Thielaviopsis paradoxa)

Fruitlet core rot (Penicillium funiculosum, Fusarium moniliforme var. subglutinans)

Pink disease of fruit (Acetomonas spp.)

Pineapple wilt (probable virus)

Yellow spot virus (tomato spotted wilt virus)

Bacterial diseases (Erwinia carotovora, E. chrysanthemi)

Nematodes (Meloidogyne spp., Rotylenchulus reniformis)

Hawaii Pesticide Information Retrieval System, CTAHR
Pineapple insects, pests, and plant disease pathogens. Knowledge Master, CTAHR


Fertilization


Pineapple has high requirements for fertilizer N, potassium (K), and iron (Fe), and relatively low requirements for fertilizer phosphorus (P) and calcium (Ca). K is usually applied to the soil before planting and later may be sidedressed. Other nutrients sometimes including K are applied as foliar sprays or through the drip irrigation system, or by both methods, during the plant growth cycle.

P and Ca are usually banded in the plant line during bed preparation. Less fertilizer is required during the first five months after planting; requirements increase sharply afterward and peak at two to four months before floral initiation.


PREPLANT FERTILIZER. The need for fertilizer applications to the soil is best determined by soil tests. In Hawaii, Ca need not be applied if soil pH is greater than 4.6, because of the low plant Ca requirement.

If soils are low in P, approximately 75 kg/ha P should be banded beneath the plant rows. Applications of animal manures may reduce the need for supplemental applications of Fe and other micronutrients.


POSTPLANT FERTILIZER. Postplant applications of fertilizers to the plant crop may provide 400 to 500 kg/ha N, 400 kg/ha K, 25 kg/ha magnesium (Mg), and 2 kg/ha zinc (Zn).

Frequent foliar applications of Fe are usually necessary in Hawaii because pineapple is not able to extract soil iron efficiently from low-pH soils. If Fe is moderately unavailable, 5 to 10 kg/ha iron sulfate (FeSO4) may suffice; where problems are more severe, 6 to 24 kg/ha may be required.


FOLIAR FERTILIZER. The volume of fertilizer solution applied foliarly to pineapple varies with plant population, growth stage, and amount of fertilizer being applied. Concentrations of fertilizer applied in sprays must be carefully calculated to avoid solutions that burn the plants.

Low-volume sprays of 250 to 500 liters/ha are directed to the green portion of the leaves, allowing little or no rundown into leaf axils. Nutrient uptake is through green leaf tissue. Salt concentration may be as high as 20 percent by weight.

Medium-volume sprays of 500 to 2500 liters/ha are directed to the green portion of the leaves, with rundown into leaf axils but with little or no runoff into the soil. Uptake is through green tissue, basal white tissue at leaf bases, and axillary roots near the base of the stem. Maximum salt concentration is 5 percent.

High-volume sprays greater than 2500 liters/ha are similar to medium-volume sprays except there is runoff of fertilizer solution into the soil at the base of the plant.

Urea is not phytotoxic at concentrations as high as 20 percent when applied to green leaf tissue only. The urea should contain less than 1 percent biuret.

Fertilizer solution concentrations should not exceed 1 percent iron sulfate or 0.1 percent zinc sulfate.


FERTILIZER REGIMES. Fertilizer is applied foliarly once a month, except for the preplant application (month 0), when Level 1 is incorporated into the soil. About 50 kg/ha of nitrogen as urea is applied at forcing when ethephon is used.

During the period between forcing and half-inch open heart, additional N may be applied if needed. Then applications should end, because fertilizer sprays will injure the inflorescence and reduce fruit yields.

Many fertilizer regimes are possible. For example, a constant fertilizer level could be applied with increasing frequency: monthly in months 1 to 3, every three weeks in months 4 to 6, and every two weeks afterward.

Another alternative is to sidedress potassium sulfate every three months and apply foliar sprays of urea and iron sulfate as needed.


CROP COLOR. Crop color can indicate its nutrient status. Pale yellow-green is acceptable during the first five months from planting in regions with a 12- to 13-month vegetative growth period. From month 5 to month 8, apply sufficient N to shift leaf color toward a darker yellow-green. After month 8, apply enough N to produce dark green plants.

All yellow should be eliminated by the time of floral differentiation, or by the time N applications are suspended before forcing.


Flowering


Flower initiation takes place at the terminal axis of the stem. This occurs naturally on short, cool days, usually in December in Hawaii.

The inflorescence is not externally visible for 45 to 60 days, when it appears in the center (heart) of the plant.


DEVELOPMENTAL STAGES. Stages of development after its appearance are called half-inch open heart and one-inch open heart. At these stages, the center is open approximately 1.25 and 2.5 cm, and the red inflorescence is clearly visible below the opening.

Three to four weeks after the one-inch open heart stage, blue flower petals can be seen at the bottom of the cone-shaped inflorescence. Before all flowers have opened, the earliest petals will have begun to dry. After all petals have dried, the inflorescence is said to be at the dry petal stage. Its surface is dull, individual fruitlets (eyes) are pointed, and a crown has just begun to develop.


FORCING. Although flowering occurs naturally only at certain times of year, artificial induction of flowering with chemicals, called forcing, may be done at any time of year if the plants are large enough (at least 1.5 kg fresh weight). This permits scheduling of planting and flowering so that harvests can be spread throughout the year. It is also used in closing out the crop to assure a complete and synchronous change at the time of natural flowering. Forcing is sometimes not completely effective during hot weather.


Forcing


The growth regulator most commonly used for forcing is ethephon, an ethylene-releasing compound that is widely used for field applications. Ethylene and acetylene are also used for forcing. In commercial Forcing with growth regulators is most effective during cooler seasons; hot weather is inconducive to good floral induction. During hot seasons (night temperatures greater than 25C), withholding nitrogen (N) fertilizer for four to six weeks before forcing can improve induction by increasing plant carbohydrate relative to N.


Insects


Scales (Diaspis bromeliae, Melanaspis bromeliae)

Thrips, vectors of yellow spot virus (Thrips tabaci, Frankliniella occidentalis)

Mites (Steneotarsonemus ananas, Dolichotetranychus floridanus)

Mealybugs (Dysmicoccus brevipes, D. neobrevipes)

Ants, associated with mealybugs (Pheidole megacephala, Iridomyrmex humilis, Solenopsis geminata)

Symphylids (Scutigerella sakimurai, Hanseniella unguiculata)

Hawaii Pesticide Information Retrieval System, CTAHR
Pineapple insects, pests, and plant disease pathogens. Knowledge Master, CTAHR


Irrigation


Irrigation by the drip system to supplement rainfall is becoming standard practice in Hawaii. The tubing is laid in the center of each bed beneath the plastic mulch. There should be one tubing orifice for every two plants. When rainfall is lacking, the irrigation system should provide 47,000 to 94,000 liters of water per hectare per week to the plants. Crowns usually are set after planting by one overhead irrigation during dry weather.

Drip irrigation may be helpful to alleviate effects of root damage due to nematode infestation. Pineapple plants irrigated by drip lines are less susceptible to moisture stress because irrigation water is delivered directly to the root zone.


Location


Pineapple is produced in Hawaii at elevations below 840 m (2800 feet) with mean annual temperatures ranging from 18.5 to 26C (65 to 79F). Good fruit quality is attributed to growing sites having a combination of relatively cool night temperatures, a high percentage of sunny days, and day temperatures ranging from 21 to 29.5C (70 to 85F), and not exceeding 32C (90F).

Wind is seldom a problem. Drought is tolerated, but yields are reduced when adequate moisture is lacking. Evenly distributed rainfall of 60 cm per year is adequate for maximum growth.


Production


Three companies dominate pineapple production in Hawaii. Large areas are planted on the islands of Lanai, Maui, and Oahu. Most of the production previously was canned, but there is an increasing trend toward producing for the fresh fruit market. There is some smallholder production on the islands of Maui and Hawaii.


Propagation


Pineapple is propagated asexually from various plant parts. For production purposes, the parts used are crowns, slips, hapas, and suckers, with crowns and slips being most common. The number and proportion of slips, hapas, and suckers produced on the plant vary with clone and climate. Special techniques are used for rapid increase of strain selections.


CROWNS. Crowns are currently the preferred planting material in Hawaii. They are twisted from the fruit at the time of harvest. The wound is allowed to dry (cure) for one to two weeks or, more commonly in Hawaii, the crowns are dipped in fungicide and planted soon after harvest. The chance of rot is reduced by trimming the crown butt to remove fruit tissue high in sugars. Crowns grow more slowly and are less drought resistant than slips but may have the potential to develop better root systems. Crowns should be graded by weight to minimize variability in the field.


SLIPS. A slip is a rudimentary fruit with an exaggerated crown. Slips develop from buds in the axils of leaves borne on the peduncle (fruit stalk). Because they must grow outward, then upward from under the fruit, slips are curved at the base. On slip-producing clones, the number of slips can vary from none, as is common in hot, equatorial zones, to as many as 10 or more, as is observed in the undesirable mutation known as collar of slips. Some clones never produce slips.

Slips become visible on the peduncle when the fruit is about half developed. When intended for use as planting material, they are harvested two to five months after the plant crop harvest, that is, 10 to 13 months after slip growth starts. When not so used, they are removed from the plant to increase ratoon yield. Slips are broken from the peduncle, then cured or dipped in fungicide. Slips may be stored butt end up in a dry place for up to one year, but they should be planted within one month of harvest for best results.


HAPAS AND SUCKERS. Hapas are intermediate in form between slips and suckers. They are produced in small numbers on plants grown in Hawaii, but in equatorial regions more hapas are produced than slips. They are borne at the base of the peduncle and, like slips, they are easily broken from the plant. Hapas are straighter than slips and lack the slips imperfect fruit structure at the base.

Suckers develop from axillary buds on the stem. Growth usually begins at floral differentiation. After fruit harvest, suckers are cut from the stem with a knife. Because suckers are large when collected, they may flower precociously after planting, increasing harvesting costs. For this reason, suckers are not used for production in Hawaii.


RAPID INCREASE METHODS:

TISSUE CULTURE. Tissue culture using meristem from axillary buds is possible if callus culture is avoided. Plants regenerated from callus tend to be variable. Growth regulators known as morphactins applied after forcing can cause production of up to 25 slips per plant. Two traditional methods are stump (stem) and crown sectioning. Plants obtained by sectioning develop slowly, and extra care in field preparation and irrigation is needed to promote rapid growth.


STUMP SECTIONING. Stumps are harvested after the one-inch open heart flowering stage or after fruit harvest. Leaves are stripped off starting at the base, or they are cut off leaving the leaf bases attached to the stump. The stump is cut longitudinally into quarters or sixths, which are then cut into wedge-shaped sections weighing 15 to 20 g, each having at least one axillary bud. The sections are dipped in fungicide and planted bud upward 2.5 cm apart and 2 cm beneath the soil in a well-prepared, fumigated nursery bed. The bed may be lightly mulched with straw or compost. As many as 50 sections may be obtained per stump. A section will produce another stump in about two years.


CROWN SECTIONING. Crowns are cut vertically into quarters or sixths, starting at the top and cutting toward the base. The vertical sections may be cut horizontally in half between the crown base and apex. After drying for one to two days, the sections are dipped in fungicide and sown 2.5 cm apart in nursery beds, with the leaves above ground. Plantlets from crown sections should reach the original crown size in less than one year. Under semisterile conditions, crowns have been microsectioned to produce up to 100 plants.


Soil Types


Acid soils are especially suited to pineapple. When soil pH is between 4.5 and 5.5, soil-borne diseases are reduced. Soil pH greater than 7.0 should be avoided. Good soil drainage is a necessity.

Where rainfall is high or soils are not well drained, soil management techniques to improve drainage must be used.

Pineapple tolerates low soil fertility, but best production is obtained with high fertility. High levels of soluble soil aluminum and manganese are tolerated. High soil organic matter and potassium status are desirable.


Weed Control


Weeds are controlled by black plastic mulch. To control weeds in bare soil areas between the mulch beds, registered preemergence herbicides cleared for pineapple may be used according to the instructions on the label. Some herbicide labels permit application of the herbicide as overtop sprays immediately after planting and at later stages during the crop cycle.


Capital & Costs



Harvest


When flower initiation occurs in December in Hawaii, ripe fruit is harvested six to eight months later. If flowering is initiated by chemical forcing at other times of the year, the period may be shorter or longer. Fruit is harvested by bending it over and twisting to remove it from the stalk.

SMOOTH CAYENNE. 'Smooth Cayenne' fruit is ripe when the individual eyes become flattened and glossy and when shell color turns yellow to yellow-orange. COlor development starts at the base and moves toward the top. 'Smooth Cayenne' is harvested when about one-third yellow for canning and when green for fresh fruit. Harvesting before ripening increases postharvest storage life, although harvesting when ripe is preferable for best fresh fruit quality. Cultivars other than 'Smooth Cayenne' may be green, yellow, red, or purple when ready to eat.


Varieties


Cultivated types of pineapple are called 'clones', because they are vegetatively propagated. There are many named clones, classed in four or five groups including 'Cayenne', 'Spanish', 'Queen', and 'Pernambuco', which may represent botanical varieties.

Commercial production is mostly based on clones in the 'Cayenne' group, also known as 'Smooth Cayenne' because the leaf margins lack spines. In Hawaii, strain selections from field populations of 'Smooth Cayenne' are grown almost exclusively.