Common Plant and Fruit Abnormalities in Pineapple

Pineapple is one of the most commercially important tropical fruits in the world, with the Cayenne group – especially ‘Smooth Cayenne’ – accounting for more than 70% of global production for both fresh and processed markets. Yet despite its widespread cultivation, pineapple crops are not without challenges. A range of plant and fruit abnormalities can reduce yield quality, complicate harvesting, and significantly impact marketability. These are not diseases caused by pathogens – they are physiological and developmental disorders arising from genetic, nutritional, and environmental factors. Understanding what causes them, how to identify them, and how to prevent them is essential knowledge for anyone involved in pineapple production.

Why the Cayenne group is particularly susceptible 🔗

The Cayenne group of pineapples – including the widely grown Smooth Cayenne variety – is particularly prone to several developmental abnormalities. Multiple crowns, fruit and crown fasciation, collar of slips, and sunscald are all disorders associated primarily with this group, largely because of the high vegetative vigour and fast growth rates typical of these varieties. Plants that are overly vigorous tend to take longer to flower, and this extended vegetative phase creates conditions where abnormal development is more likely to occur. Growers working with Cayenne-type pineapples need to be especially attentive to nutrient management, planting density, and environmental conditions throughout the crop cycle.

Multiple crowns 🔗

Under normal conditions, a pineapple fruit bears exactly one crown – the leafy shoot at the top. When multiple crowns develop, the top of the fruit becomes flat and broad, making it unfit for canning. Such fruits are also known to taste insipid and have a corky texture, and the condition is considered a heritable character found mostly in the Cayenne group.

From a commercial standpoint, fruits with multiple crowns present real problems. They don’t conform to standard packaging dimensions, which makes them difficult to process or export, and their irregular appearance tends to put off fresh-market buyers. Excessively wide plant spacing has been shown to promote multiple crown development in Smooth Cayenne in Hawaii, which means planting density is a key management variable growers should not overlook. Maintaining recommended spacing and selecting planting material from plants without a history of this abnormality can help reduce its frequency over successive crop cycles.

Fruit and crown fasciation 🔗

Fasciation is an abnormal growth condition in vascular plants where the apical meristem – normally concentrated at a single point – becomes elongated, producing flattened, ribbon-like, or fan-shaped tissue instead of the usual cylindrical growth. In pineapples, fasciation can affect both the fruit and the crown, with results ranging from mildly distorted shapes to severely deformed fruits that are completely unmarketable.

What fasciation looks like in pineapple 🔗

Fasciated pineapple fruits are deformed to such an extent that they become totally useless. In extreme cases, proliferation is so severe that the fruit is highly flattened and twisted with innumerable crowns. When the crown is affected, it takes on a flat, fan-like structure rather than the typical upright rosette. The fruit may develop an irregular, elongated, or multi-lobed form that cannot be packed or processed using standard equipment.

Causes and contributing factors 🔗

Fruit and crown fasciation in pineapple is associated with high plant vigour – plants that take longer to flower are more susceptible. High soil fertility, warm weather, and deficiencies of calcium or zinc are all known to favour the condition. Beyond these crop-specific factors, fasciation in plants more broadly can result from genetic mutations, physical injury to the growing tip, chemical exposure, or even bacterial infections – particularly by Rhodococcus fascians, though genetic and nutritional causes are more commonly implicated in pineapple.

Management 🔗

Since high fertility and zinc or calcium deficiency are known triggers, balanced fertilization is the most practical preventive measure. Avoid over-application of nitrogen and ensure adequate micronutrient levels through soil and foliar testing. Selection of resistant varieties is also recommended where available. Fasciated planting material should never be used for propagation, as the condition can have a heritable component.

Collar of slips 🔗

Slips are the small plantlets that develop from buds in the leaf axils along the fruit stalk (peduncle). Under normal conditions, a pineapple plant produces a manageable number of slips – useful for vegetative propagation. The “collar of slips” abnormality is a different situation altogether.

Symptoms and impact on fruit 🔗

The collar of slips is typified by the presence of a large number of slips arising from the stem close to the base of the fruit, or even directly from the fruit itself. The excessive slip growth comes at the expense of the fruit, resulting in small, tapered fruits, often with knobs at the base. The fruit appears to be surrounded by a ring of small shoots – the “collar” – which compete with the developing fruit for assimilates, ultimately reducing both fruit size and quality.

In severe mutations, the number of slips around a fruit can reach 10 or more, well beyond what would be considered normal for the variety. For growers targeting fresh fruit markets where size and appearance matter greatly, collar of slips can cause significant crop losses.

Causes and prevention 🔗

High nitrogen fertilization and high rainfall combined with relatively low temperatures are considered conducive to this abnormality. This means that crop nutrition and irrigation management both play a role in its prevention. Avoiding excessive nitrogen inputs – particularly during fruit development – and ensuring good drainage to prevent waterlogging can reduce the risk. Growers should also avoid using planting material sourced from plants that previously exhibited this condition.

Sunscald 🔗

Sunscald is perhaps the most visually dramatic of the common pineapple abnormalities, and it is also one of the most straightforward to understand from a cause-and-effect perspective.

How sunscald occurs 🔗

Sunscald results when a plant leans or falls over to one side, exposing one side of the fruit to direct sunlight. The cells on the exposed surface get damaged, and the shell surface gradually turns brownish to black, with cracks appearing between the fruitlets. Affected fruits soon rot and become infested with pests. High temperatures combined with intense solar radiation accelerate cell damage, while low humidity and strong winds can worsen the condition by increasing water stress in the fruit tissues.

The UC Davis Postharvest Research and Extension Center lists sunscald as one of the primary quality defects that reduces pineapple marketability, alongside bruising, cracks, and internal breakdown. Once sunscald damage sets in, secondary fungal or bacterial infections quickly follow, making the fruit unsalvageable for commercial purposes.

Prevention and management 🔗

Affected fruits must be removed as soon as noticed and safely disposed of to prevent contamination of other fruits. High-density planting significantly reduces the intensity of sunscald by providing natural shading between plants. In areas with lush leaf growth, leaves can be tied around the fruit to protect them from direct sun exposure. Alternatively, the sun-exposed portion of the fruit can be covered with dry straw, grass, or any locally available protective material.

Proper staking and support of plants that tend to lean – especially in high-wind or waterlogged conditions – is also an important preventive step. In high-density planting systems, the mutual shading of adjacent plants greatly reduces sunscald incidence, making plant population management a dual-purpose tool: it improves yield per unit area and also protects fruit from sun damage.

General management principles for reducing abnormalities 🔗

While each abnormality has specific triggers, there are several common-sense agronomic practices that help reduce the overall incidence of developmental disorders in pineapple:

Use healthy, disease-free planting material: Avoid sourcing crowns, slips, or suckers from plants that have shown abnormalities in previous cycles, particularly for heritable conditions like multiple crowns.

Maintain balanced nutrition: Excess nitrogen encourages collar of slips, while calcium and zinc deficiencies promote fasciation. Regular soil testing and calibrated fertilizer application are essential. Standard Smooth Cayenne production guidelines recommend careful attention to zinc and other micronutrients as part of a complete fertilization program.

Optimize planting density: Adequate plant density reduces the risk of multiple crowns and provides natural protection against sunscald. Excessively wide spacing is a known risk factor for multiple crown formation in Cayenne varieties and should be avoided in commercial plantings.

Monitor crops regularly: Early detection of developing abnormalities – particularly fasciation and sunscald – allows timely intervention. Affected fruits and plant material should be removed promptly to prevent further spread or contamination.

Manage the growing environment: Adequate drainage, controlled irrigation, and windbreaks where applicable all contribute to reducing stress-related developmental disorders. Stable growing conditions reduce the hormonal and nutritional imbalances that underlie most of these abnormalities.

Pineapple abnormalities are rarely caused by a single factor. They are the outcome of interactions between variety susceptibility, soil conditions, weather, and crop management practices. Most common physiological disorders of pineapple – including multiple crowns, fasciation, collar of slips, and sunscald – result in significant financial losses for fruit growers, making proactive management far more cost-effective than reactive measures after the damage is done.

What do you think? Given that several pineapple abnormalities like fasciation and multiple crowns are linked to both genetic factors and nutritional imbalances, do you think variety selection or soil nutrition management plays the bigger role in reducing their incidence? And with sunscald being largely a structural and environmental problem, how do you think small-scale pineapple growers with limited resources can best protect their crops from sun damage?

References

1. https://www.itfnet.org/v1/2016/05/pineapple-common-varieties/
2. https://nhb.gov.in/pdf/fruits/pineapple/pin003.pdf
3. https://www.itfnet.org/v1/2016/05/pineapple-agronomy/
4. https://en.wikipedia.org/wiki/Fasciation
5. https://pnwhandbooks.org/plantdisease/pathogen-articles/common/fasciation
6. https://www.researchgate.net/publication/376238250_Physiological_Disorders_and_Management_of_Pineapple_Pomegranate_and_Papaya
7. https://www.ctahr.hawaii.edu/oc/freepubs/pdf/f_n-7.pdf
8. https://postharvest.ucdavis.edu/produce-facts-sheets/pineapple
9. https://www.slideshare.net/slideshow/abiotic-stress-management-in-pineapple/248292865