Cultural Practices

A. Propagation and Nursery Management

Propagation of mangoes can be done through several methods, with the primary two being sexual (through seeds) and asexual (through vegetative means). Each method has its place, with sexual propagation used for rootstock production and breeding programs, while asexual propagation is used for commercial fruit production to ensure consistency in fruit quality and tree characteristics.

Sexual propagation:

Mango seeds need to be planted soon after extraction from the fruit as they quickly lose their viability. The pulp is typically removed from around the seed, which is then dried in the shade. For uniform germination, the kernel is often taken out of the hard endocarp (husk). The seed is then planted with the concave side facing downward into a sandy substrate that facilitates easy transplanting of seedlings with minimal root damage. Seedlings from polyembryonic seeds, common in South African cultivars, produce multiple offspring, of which only the strongest are chosen for further growth. These seedlings are raised under partial shade until they are ready to be transferred to the field.

 Mango seeds are categorised into two types: mono-embryonic and poly-embryonic. Mono-embryonic seeds produce a single embryo, resulting in just one offspring per seed. In contrast, poly-embryonic seeds contain multiple embryos, enabling the generation of several offspring from a single seed. This distinction is crucial for mango propagation, as it influences the genetic variability and cultivation methods of the resulting plants.

Asexual propagation:

Asexual methods include grafting and budding, which are preferred for commercial production due to the uniformity and quality of the produce. In South Africa, grafting is often practised by joining a scion from a desired cultivar onto a robust rootstock, like the common Sabre, which is favoured for its resilience and compatibility with various cultivars. This method ensures the preservation of the cultivar’s characteristics and promotes earlier fruiting compared to plants grown from seeds.

B. Field Preparation

Land preparation for mango cultivation involves processes akin to those for other tree crops. It often requires deep ripping to disrupt any hard layers of subsoil that might impede root growth. In scenarios where the soil is excessively alkaline, sulfur is incorporated to lower the pH to a level more conducive to mango growth. This stage is also opportune for the addition of organic matter, which can be integrated into the soil without any obstruction from the tree canopy, enhancing soil fertility and structure.

C. Transplanting and Plant Spacing

Transplanting mango trees is ideally timed just before or at the beginning of the wet season when irrigation facilities are not available. To enhance the nutrient content of the soil, organic matter and phosphorus fertilisers are often added to the planting hole, which typically measures 0.5 meters in all dimensions. After transplanting, mango trees do not require shading.

The spacing between the trees is a critical factor that varies based on environmental conditions, soil properties, the vigour of the chosen cultivar, and the orchard management strategy. Spacing can range from as narrow as 6 meters by 3 meters to as wide as 7 meters by 15 meters. High-density planting, with spacing as close as 3 meters by 2.5 meters, has been experimented with for grafted trees. Although this approach reduces the yield per individual tree, the total orchard yield increases, necessitating substantial pruning to manage the dense growth.

In subtropical regions, closer spacing such as 6 meters by 4 meters or 6 meters by 3 meters is preferred. This arrangement requires more intensive formation pruning and regular annual pruning to keep the trees’ size manageable and ensure optimal sun exposure and air circulation, which are vital for the health and productivity of the trees.

D. Irrigation

Table 6.25: Water needs of mango trees based on their age.

Tree Age	Water Volume	Frequency	Notes
0 to 3 months	20 to 30 litres	Every 4 to 5 days	Essential for establishment. Adjust based on soil type and weather conditions.
4 to 12 months	40 to 50 litres	Every 7 to 10 days	Increased rates as trees grow.
2nd year	100 to 150 litres	Every 10 days	Adjust according to dry periods.
3rd year	200 to 300 litres	Every 15 days	Tailor to soil type and rainfall.
4th year+	400 to 500 litres	Every 2 weeks	Required during fruit development, cut off as fruits mature. Resume post-harvest for vegetative growth.

In South Africa, young mango transplants typically need around 20 to 30 litres of water every 4 to 5 days during the initial 2 to 3 months post-planting to ensure proper establishment. As the trees mature over the first year, this amount is increased to 40 to 50 litres at intervals of 7 to 10 days. In the second year, watering rates are raised to about 100 to 150 litres every 10 days, and this may be adjusted based on the specific dry periods experienced.

By the third year, a watering rate of 200 to 300 litres per tree every two weeks is usually sufficient. However, this is variable and depends on soil type and rainfall patterns. For instance, in areas with sandy soils or during extended dry spells, the frequency and volume of irrigation may need to be increased to meet the trees’ demands.

As trees reach the age of four to five years and start bearing fruit, cultural practices shift to accommodate the trees’ changed nutritional and water needs. It is beneficial for bearing trees, especially in tropical regions, to undergo a dry period of 3 to 4 months before flowering to discourage excessive vegetative growth. This dry period often naturally aligns with the region’s dry season. When the trees flower and set fruit, irrigation is essential, particularly in the first 4 to 6 weeks when fruit cells are dividing rapidly, and moisture stress can detrimentally affect development.

For a four-year-old tree, around 400 to 500 litres of water per tree every two weeks may be necessary. As the fruit matures, irrigation is halted to promote higher sugar content in the fruit. Post-harvest, heavy watering is resumed to encourage new vegetative growth. In regions where the end of the harvest season coincides with the rainy season, such as in the monsoon tropics, additional irrigation is often not needed.

The selection of irrigation systems and management strategies in South Africa is dictated by the efficiency and capacity of water delivery, as well as the cost of equipment and installation. Proper irrigation scheduling aligns with the tree’s phenological growth cycle to optimise yield.

Table 6.26: A summary of the irrigation needs of mango trees.

Stage	Water Volume	Frequency	Notes
Pre-flowering (dry period)	None	N/A	A dry period of 3 to 4 months to reduce vegetative flush growth, coinciding with the natural dry season if possible.
Flowering to Fruit Set	As needed	Adjust to flowering time	Ensure adequate irrigation during fruit set.
Fruit Development	As needed	Adjust to development	Avoid moisture stress during the first 4 to 6 weeks of fruit development.
Pre-harvest	None	N/A	Stop irrigation as fruits approach maturity to enhance sugar content.
Post-harvest	Heavy	Resume immediately	To encourage new vegetative growth. Coincides with the rainy season in the monsoon tropics, so additional irrigation is unnecessary.

E. Pruning

Pruning and training are vital cultural practices in mango orchard management, designed to control tree size and shape the canopy for optimal growth and fruit production.

Table 6.27: Summary of the pruning practices for mango trees.

Practice	Details
Formation Pruning	Starts in the nursery or after transplanting. All lateral shoots are removed up to 70 to 100 cm. For varieties with drooping branches, the top is trimmed to encourage lateral growth. Select three primary branches, well-spaced and angled.
Training for Compactness	Once primary branches mature, pinch terminal buds to encourage bushy growth. Repeat this process to form a dense canopy with multiple branch tiers. Adjust the pinching frequency based on the desired compactness.
Canopy Management	For less dense canopies, pinch every second or third flush. Open the centre by removing interior branches for light penetration.
Pruning for Espaliers and Trellises	Pinch at the height of the first wire, directing new shoots along and up to the second wire.
Annual Pruning	Not commonly practised but occasional thinning is necessary for light and air penetration, and to remove dead or diseased wood. In Florida, mechanical ‘ledgers’ and ‘toppers’ are used post-harvest to maintain tree size.
Pruning for Space Management	Drastic pruning of overgrown trees can result in years of lost income. Regular pruning to control height is more sustainable.
Biennial Flowering Cultivars	Remove shoots that have flowered to encourage new flowering shoots.
Synchronisation Pruning	In the lower tropics, light peripheral pruning is performed post-harvest to promote uniform new growth and flowering.

This table provides a structured overview of the pruning and training techniques utilised in mango cultivation, specifically tailored to subtropical regions where narrower plant spacings and smaller tree sizes are preferred.

F. Fertilisation

In the context of fertilisation for mango trees in South Africa, the amounts and timing of fertiliser application are dictated by the tree’s growth and flowering cycle. For the initial three years, young trees receive roughly 113 to 227 grams of a complete NPK (Nitrogen, Phosphorus, Potassium) fertiliser three times annually. As trees mature from the fourth year onwards, which coincides with the start of commercial yield production, fertilisation is reduced to twice a year. The first application coincides with the onset of the first inflorescence and the second follows the harvest to encourage new vegetative growth.

Placement of the fertiliser is critical; it should be applied where the density of feeder roots is highest, which is typically about 90 to 175 centimetres from the trunk and up to a depth of 20 centimetres. Additionally, irrigation post-fertilisation is essential to facilitate nutrient uptake.

Different mango-growing regions have developed their own specific fertiliser formulations and application rates. For mature trees, a balanced fertiliser with an NPK ratio of about 15:15:15 is common. The quantity and ratio of fertiliser can vary, with some regions recommending higher amounts of nitrogen and potassium to boost the yield, colour, and sugar content of the fruit. However, exceeding the recommended levels of nitrogen can lead to unfavourable outcomes such as diminished external colour and flesh firmness. Monitoring leaf nitrogen levels is also important, as levels above 1.5% can lead to reduced fruit size and increased susceptibility to certain diseases and ripening issues. It is important to refer to established critical nutrient levels for mango leaves to guide fertilisation practices.

Table 6.28: All fertiliser applications should be supported by leaf and soil analyses.

Tree Age	Fertiliser Application	Amount (NPK)	Frequency	Application Timing
1 to 3 years	Complete NPK fertiliser.	113 to 227 g/tree.	3 times per year.	–
4+ years (mature)	Complete NPK fertiliser.	Varies.	2 times per year.	1. At the onset of inflorescence. 2. After harvest.

G. Flower Synchronisation

Flowering synchronisation and induction in mango production are critical aspects of orchard management, especially in biennial-bearing trees that exhibit alternate-year cropping. Ethephon, an ethylene-releasing compound, is used to enhance flowering and fruiting during off years. Traditional practices like smudging, used in the Philippines, involved burning materials such as rice straw near trees to encourage flowering, likely due to ethylene release. Modern techniques now offer more sophisticated approaches for commercial use.

In South Africa’s subtropical regions, cool winter temperatures and water stress are natural inducers of flowering. However, excessive flowering in young plants can impede growth, so blooms may be removed to allow trees to reach the desired size. In the tropics, flowering induction is less reliant on temperature and more on the timing post the last vegetative growth flush.

Effective orchard management for advancing flowering considers several factors: appropriate nitrogen levels in leaves, adequate soil moisture (not too low), maturity of shoots, and the use of growth regulators like paclobutrazol to control vegetative growth. Spraying flowering stimulants, such as nitrates, is another method, although its success depends on factors like leaf maturity, leaf nitrogen concentration, soil moisture, and application timing.

The steps to induce flowering include stimulating new vegetative shoot production, checking vegetative growth with growth inhibitors, and spraying flowering stimulants. The response to these treatments varies among cultivars, with some responding more readily than others. Ultimately, the objective is to manipulate the tree’s natural cycles to achieve optimal flowering and fruiting that align with market demands, ensuring profitable yields for mango farmers in South Africa.

 

Table 6.29: Chemicals for manipulating flowering or increasing fruit set and retention in mango (Source: Tropical Fruits, 2nd Edition, Volume 1; R.E. Paull and O. Duarte).

Area	Chemical	Application time	Dosage (foliar sprays)	Action
Subtropics	GA3	Before flower differentiation (beginning of winter).	100 mg/l	Delays flowering (repeated use during winter will eliminate flowering).
	Cyclohexamide	Flowering.	0.25 g/l	Destroys apical panicles.
	Dinoseb	Flowering.	0.5 ml/l	Destroys apical panicles.
	Pentachlorophenol	Flowering.	5.0 g/l	Destroys apical panicles.
	Ethephon	Full-flower stage.	800 mg/l	Destroys apical panicles.
	Hydrogen cyanide	Beginning of flowering season.	0.4 % (cv. Haden) 0.6 % (cv. Keitt)	Destroys apical panicles.
Tropic	NH4NO3	End of autumn.	20 g/l	Interrupts flower dormancy.
	KNO3		40 g/l
	Paclobutrazol	Any time during fruit bud stage or even at the end of autumn.	2.5 to 5.0 g tree (soil drench).	Reduction of vegetative growth and flower induction; increases fruit set.
General	Polyamines
	spermine	Before anthesis or at full bloom.	10-1 M	Increase fruit set and fruit retention.
	Putrescine	Full bloom.	10-4 M
	KNO3		2 to 4 %

 

Pest Management

A. Diseases

In mango production, anthracnose caused by Colletotrichum gloeosporioides is one of the most significant diseases affecting leaves, flowering panicles, and fruit, leading to substantial yield losses. This fungal disease is particularly severe in regions with high humidity and frequent light showers during the flowering period, such as Hawaii, where it can destroy almost all the inflorescences. In some areas, like the Ryukyu Islands in Japan, growers resort to constructing polyethylene shelters over the trees to shield the blossoms from rain. Cultivars like ‘Carabao’, ‘Keitt’, ‘Tommy Atkins’, and ‘Zill’ have shown some resistance to anthracnose, which is crucial for regions like South Africa, where the disease is prevalent. Control strategies include regular fungicide sprays during flowering and maintaining orchard hygiene to reduce inoculum levels.

Powdery mildew, caused by Oidium mangiferae, is another common disease, particularly in the dry subtropics. It can be managed with the same treatments used for anthracnose. Continued protection is necessary until the fruits grow to the size of a cherry. Mango inflorescence malformation is a serious condition caused by Fusarium moniliforme, with mites also implicated in its spread. Management includes the use of growth regulators and careful pruning of affected areas. In South Africa, bacterial black spot caused by Xanthomonas campestris poses a threat to mango production. Vigilance and appropriate treatments are necessary to manage this disease effectively.

Table 6.30: A summary of the most common diseases found on mangoes in South Africa.

Disease and Causal Organism	Image	Symptoms	Control Method
Anthracnose Colletotrichum gloeosporioides		Attacks leaves, flowering panicles, and fruit. Causes significant yield reductions, especially when inflorescences are affected.	Regular fungicide sprays during flowering, alternating systemic and protectant fungicides. Maintain orchard hygiene.
Powdery Mildew Oidium mangiferae		Affects leaves, stems, and inflorescences, common in dry subtropical areas.	Treatments for anthracnose typically also control powdery mildew; continue treatment until fruits are cherry-sized.
Mango Inflorescence Malformation Fusarium spp.		Malformed vegetative shoots and flowering panicles, panicles become short and compacted.	Use of growth regulators like GA3 and NAA, pruning malformed panicles, and spraying with copper oxychloride.
Bacterial Black Spot Xanthomonas campestris		A relatively serious disease in South Africa and Australia.	Implementing phytosanitary measures, using copper-based bactericides, and resistant cultivars where available.

B. Insects and Other Pests

Mangoes, a valuable export commodity, are significantly affected by pests like the Mediterranean and Oriental fruit flies, which are widespread and pose a challenge, especially for international trade. These flies lay eggs in ripening fruit, leading to larval infestation that renders the fruit unexportable to many countries. South Africa, among other mango-growing regions, uses measures such as irradiation, hot water, and vapour heat treatments to meet the disinfestation requirements of importing countries.

Control strategies adopted in South Africa include early harvesting to minimise exposure, removal of fallen fruits, and the use of traps for monitoring adult fly populations. Biological control techniques, like the release of sterile males, have proven effective in isolated areas. Chemical baits containing Malathion are also utilised. Additionally, fruit bagging, though labour-intensive, ensures high-quality fruit free from fly damage and disease, leading to a higher percentage of marketable produce.

The mango seed weevil is another pest affecting exports, requiring stringent control measures such as field sanitation, chemical sprays, and the use of pest-free zones. This weevil’s life cycle involves laying eggs on young fruit, with larvae burrowing into the seed and adults emerging from the ripe fruit. Although the presence of weevils does not typically affect the fruit’s edibility, it can cause decay and premature drop.

 Mango seed weevil, Sternochetus mangiferae.

In addition to the common insect pests that afflict mango crops, wildlife can also pose a threat to mango production. Birds, bats, and monkeys are known to feed on mango fruits, causing damage that not only reduces the yield but can also affect the export quality of the produce. These animals are attracted to the sweet flesh of the mangoes and can cause significant losses, especially when the fruits begin to ripen and emit their characteristic aroma.

In South Africa, fruit bats, known for their nocturnal feeding habits, can pose a significant challenge to mango crops due to their potential to cause extensive damage. However, given their status as an endangered species, it is crucial to approach control methods with caution. It is illegal to harm or kill bats in South Africa, so any measures taken to protect mango crops must comply with conservation laws and prioritise humane and non-lethal methods.

Birds such as parrots, starlings, and mynahs are also known to peck at ripening fruits, which can lead to secondary infections by fungal and bacterial pathogens.

 Parrot feeding on mango.

Control measures for wildlife pests include netting to physically exclude birds and bats from accessing the trees. Sound deterrents, reflective objects, and scare devices can sometimes be effective at keeping birds away. However, these methods need to be managed carefully to prevent habituation. Where legal and appropriate, some farmers may opt for culling or relocating the animals, but these methods come with ethical considerations and must comply with local wildlife conservation laws.

For larger animals like monkeys, which are intelligent and can overcome simple deterrents, more sophisticated measures such as electric fencing or the use of guard animals like dogs may be necessary. Mango farmers need to balance pest control measures with the conservation of local wildlife species and biodiversity. Integrated pest management strategies that consider the behaviour and ecology of these animals can be more effective and sustainable in the long term.

 

Harvesting

Harvesting mangoes is a delicate process that requires careful attention to ensure that fruits are picked at the right stage of maturity for optimal flavour and shelf life. In South Africa, as in other mango-growing regions, indicators of maturity include a change in colour, a fullness of the cheeks of the fruit, and a hardened endocarp. The most accurate, though destructive, method is to check for a yellowing of the flesh near the seed, which signifies that the endocarp has hardened.

The colour change of the skin in mangoes is not a reliable indicator of maturity because mangoes, depending on the variety, can exhibit a wide range of colours at full ripeness. Some cultivars may remain green even when ripe, while others turn yellow, orange, or red. Additionally, external factors such as sunlight exposure, temperature variations, and tree nutrition can affect the skin colour without necessarily correlating with the internal maturity of the fruit.

Mangoes can also experience colour changes while still immature, which can mislead harvesters if colour is their only cue. Moreover, some mangoes may develop a mature colour prematurely due to stress conditions, such as drought or nutrient deficiencies, but the internal quality of the fruit – flavour, texture, aroma – may not have developed fully. Hence, other signs of maturity, including the fullness of the fruit’s cheeks, firmness, and particularly the hardening of the endocarp and yellowing of the flesh near the seed, are more accurate indicators of true maturity. These signs are more directly related to the physiological changes occurring inside the fruit as it ripens.

Farmers often use the date of fruit set as an index for harvest timing. By noting when a high percentage of fruit initially sets on the panicle, they can estimate the optimal harvest date. Traditionally, the dropping of the first fruit has been used as an indication that the remaining fruits are ready for harvest.

Mango harvesting is done manually to ensure gentle handling and prevent damage. Ground crews can reach fruits by hand or with the use of ladders, while long poles with a metal basket or cloth bag are used to harvest fruit from higher branches. In some cases, one person may climb a ladder to cut the fruit, carefully dropping it into the waiting hands of a partner on the ground. This method is labour-intensive but necessary to maintain the quality of the fruit for both the local market and for export.

 A cloth basket is used to gently catch a harvested mango.

 

Postharvest Handling

Post-harvest handling of mangoes is crucial to maintain quality and prevent disorders that can impact marketability. During harvesting, mangoes should be picked with a short length of peduncle to manage sap flow, which can cause sap burn if left on the skin. In the field, harvested mangoes are placed in the shade or in specialised boxes with the cut peduncle facing down, allowing the sap to drain without damaging the fruit.

 Postharvest transportation to the packhouse.

Once transported to the packing house, mangoes are washed to remove sap residue and the peduncle is trimmed. Hot water treatment can control anthracnose, and fungicides or chlorine may be added to the wash water to prevent other diseases. Mangoes are graded based on size, colour, and absence of defects, and then packed with care to avoid bruising.

Shelf life at room temperature is relatively short, so precooling and controlled temperatures are beneficial for extending it. Treatments with calcium chloride dips can improve shelf life, which varies with cultivar and harvest maturity. Ethylene treatments can accelerate ripening, with the ideal ripening temperature range being 21 to 24°C.

Controlled atmosphere storage has shown potential, but the benefits can vary with cultivars and may not be commercially viable. Modified atmosphere packaging and waxing can delay ripening and reduce water loss.

Chilling injury, sap burn, internal breakdown, jelly-seed disorder, and lumpy tissue are among the post-harvest disorders affecting mangoes. Chilling injury occurs at low temperatures and manifests as skin scald and increased disease susceptibility. Sap burn from latex can cause skin browning and is managed by careful harvesting and washing. Internal disorders such as jelly-seed are not pathogenic but result from physiological stress; they are best managed by harvesting before full ripeness. Each of these factors requires careful management to ensure the highest quality of mangoes for the market.

 

Grading

In South Africa, the sale of mangoes is regulated by specific standards to ensure quality and safety. Key regulations include:

• Class System: Mangoes must be sold according to the classes defined in regulations, namely “Class 1”, “Class 2”, and “Lowest Class”.
• Quality Compliance: They must meet the quality requirements as per Regulation 4, which includes standards for size, colour, and freedom from defects.
• Packaging: Mangoes must be packed in prescribed containers and manners as outlined in regulations 5 to 9. This excludes mangoes sold loosely to the informal trade.
• Marking: Mangoes need to be appropriately marked with details like country of origin, producer’s name, class of mango, cultivar, size, and so forth, as per regulation 10.
• Chemical and Biological Contaminants: They must not contain any prohibited substances or exceed the maximum limits for biological or chemical contaminants as per the Foodstuffs, Cosmetics and Disinfectants Act 1972.

Vendors selling mangoes in public places like streets are exempt from certain stipulations, except if the mangoes are marked in terms of specific items. The Executive Officer may grant exemptions from these regulations under certain conditions. These regulations ensure that mangoes sold in South Africa are safe, of good quality, and correctly labelled, thereby protecting consumers and maintaining market standards.