Tree of the month: Close encounters with mango trees in Trinidad and Tobago

EXACTLY 50 years ago I arrived in Trinidad and Tobago to study for a PhD degree in tropical plant pathology at the St Augustine Campus of the University of the West Indies (UWI). Until then I had never seen a mango tree, let alone tasted its fruit, and I’m not sure I had even heard of Mangifera indica. Enquiries at Fred the greengrocer’s would have been met with the predictable ‘we don’t do that foreign rubbish here, mate – how about a pound of English Cox’s Orange Pippin?’

MANGO – APPLE OF THE TROPICS

However, I would soon be introduced to a ‘tropical peach’, although, apart from taste and texture, mango has more in common with the apple (Malus domestica). Like the proverbial apple, everyone has a tree in the garden. And, like traditional apple trees, mango was a big tree requiring a climb to pick the fruit, but with enormous differences in scale, as I was soon to find out.

Munch on an apple and throw away the core or suck a mango and discard the stone and net result is the same – a regenerating tree. That’s one of the reasons Trinidad was dotted with mango trees as tall as mature English oak trees, the only difference being that it takes just two decades to attain these dimensions, compared with at least 80 years for oak. This was the Equatorial tropics where you can almost see things grow. In canopy shape, mango reminded me of English elm rather than English oak, and just as well because by the time I got home, ten years later, English elm was gone, having succumbed to Dutch elm disease.

The Indian subcontinent is the natural home of Mangifera indica, although mango is now distributed as far as climate will allow. Mango is grown commercially as far north as Israel, Sicily, and Andalusia in Spain, although still essentially tropical in its requirements.

Traditional mango trees are massive and frequently match forest trees in size.

FOLIAR FLUSHING AND DISEASE CONTROL

Like many tropical evergreens, mango shows distinct patterns of flowering and foliar flushing in response to seasonal rainfall because temperature and day length is essentially consistent throughout the calendar year. Mango trees in Trinidad flower and flush in March/April after several months of dry season but with the wet season and heavy rain on the horizon. Individual flowers are tiny but borne in massed panicles, which can cover the entire canopy.

Leaf flushing presents the plant pathologist with real problems. Flushes of new leaves without well-formed protective cuticles are highly susceptible to infection. The most ubiquitous, frequent and severe disease for mango is anthracnose, caused by the fungus Colletotrichum gloeosporioides, which spreads all over new leaves like a rash. Infection takes place while new leaves, initially coloured pink, hang limp in bunches alongside the dark-green mature leaves massed along the branches. Leaf infections rapidly spread onto flowers and newly formed fruits and remain latent until ripe fruits are picked, only to explode post-harvest and destroy the harvested fruit before it can be sold and eaten.

The simple solution is a programme of copper fungicide sprays starting at leaf flushing and flowering and continued through season as the fruit grow and develop. Copper is the silver bullet for tree diseases in the tropics including leaf rust of coffee and Phytophthora pod rot of cocoa, as well as mango anthracnose.

Anthracnose, seen here affecting ripe mango fruit, is the most widespread and frequently occurring disease of the mango tree.

Copper-containing fungicides have been used safely and successfully since the 1880s. Having broad-spectrum activity, they control bacterial plant pathogens and keep trees clean of damaging epiphytic growth such as algae, lichens, mosses, ferns and bromeliads, as well as controlling a huge range of fungal pathogens; and especially so for cuprous oxide, containing 80+ per cent active copper and with a fine particle size distribution conferring tenacity and high weathering resistance to fungicide deposits on the leaves.

Mango trees blossom in abundance in response to the change from dry to wet seasons in the tropics.

Trinidad mangoes come in all shapes, sizes, colours and flavours. Most common is ‘Mango Rose’, similar in size, shape, ripened colour and taste to the Brazilian mangoes sold in supermarkets at 99p a pop. ‘Mango John’ is a more oblong and flavourful fruit but rife with fibres that get stuck in the teeth. ‘Mango Long’ is similar but without the annoying fibres. ‘Mango Starch’ is sweet and juicy but with a chalky feel to the texture. ‘Mango Turpentine’ is clearly an acquired taste. Biggest and boldest are ‘Mango Calabash’ and ‘Mango Belly Full’, while most diminutive, colourful and sweet is ‘Mango Dou-dous’, described in the Trinidad folk song ‘Mangoes’ by Olive Walke:

Mango dou-dous, sou se matin,

Savez-vous all for me,

Mango dou-dous, sou se matin,

Savez-vous, all for meeeeeeee!”

READ MORE: Tree of the month: A rose by any other name

Christopher Columbus claimed Trinidad for Spain in 1498. It remained a Spanish possession until 1797 but with a distinctive and overriding French culture. Great Britain added the island to its long list of Crown Colonies in 1797. Subsequent linguistic transition from French into English created a whole new dimension for the local French Patois language, confusing to say the least. I have seen ‘Mango dou-dous’ alternatively written as ‘dou-dou’, ‘doo-doo’ and ‘dou-douce’. ‘Dou-dous’ translates into ‘I give two [mangoes]’ and perhaps relating to the seller because the mangoes were so small.

That such large fruits should develop from the pollination and fertilisation of such tiny mango flowers continues to amaze.

MANGO TIMBER AND WOOD

Mango is famous for its densely grained hardwood in a kaleidoscope of colours, weighing in dry at 675 kg/m3, exactly the same as English oak but denser than teak (655 kg/m3). Mango wood is used to make furniture, is a good structural alternative to English oak and teak, and, as the by-product of fruit growing, is more sustainable too. Unlike the towering oaks of North America and Europe, which take a century or more to mature, mango trees mature quickly to reach 80 feet in around 20 years. Once the trees get too tall to easily harvest the fruit, or stop bearing fruit altogether, they are harvested for timber and a new generation of fruit trees planted. Reports suggest the sappy nature of the wood means mango does not make good firewood.

New mango leaf flushes initially pink in colour hang limp from the branches.

CLOSE ENCOUNTERS WITH MANGO TREES

Mango trees in ancient India were associated with Manmatha, the god of love, and mango blossoms were considered to be the god’s arrows by the Hindu Nanda kings. However, there is a darker side to mango, as I was soon to find out in Trinidad.

The first close encounter was soon after I arrived. I was in Central Trinidad with my friend, Ted Burleigh, who was researching tobacco for his diploma in tropical agriculture. As with oaks in England, mango trees are planted as field markers or as shade for cattle. There was a big tree in the tobacco field, which I decided to climb to investigate a bird’s nest,  but on the way disturbed the nest of a Jack Spaniard, a large tropical wasp with a nasty sting. Fortunately, a visit to the local Trini-Chinese shop for Tiger Balm for the stings and shots of Old Oak Rum did the trick.

Birds (and wasps) are not the only creatures taking refuge in mango trees. I recall sodden September soirées during the height of the wet season with mangoes now in full fruiting mode. I was sitting high on the balcony of my in-laws’ house watching drips falling from leaves on a mighty Mango Rose tree before my very eyes, hearing the periodic thud of ripe mangoes falling onto the galvanized iron roof. If you were lucky, a mango might fall into your very lap but so could one of the snakes taking refuge in the tree from the torrential rain. I can’t remember whether it was a coral snake or the mapepire (both highly venomous) or a harmless species, but a snake was a snake in 1970s Trinidad where whack-a-snake was the final solution, delivered swiftly with a heavy wooden rod hewn from mahogany, teak or other locally grown hardwood.

Suck a mango, discard the seed, and the result is a new tree.

After several years, I noticed a distinct nasal blockage coinciding with Eastertide. I was X-rayed and diagnosed with ‘small sinuses’. Back in England, I visited an allergy clinic where a series of pinpricks and droplets up my arm identified an allergy to mango blossom. How such tiny flowers can cause so much metabolic trouble, let alone develop into such big fruits, still amazes me.

I was warned about picking mangoes without protection but forgot and ended up with painful burns and scabs after picking the fruit in West Africa. Mango ‘milk’ (sap) containing highly acidic and toxic urushiol squirts out from the broken fruit stalks. This is no big surprise – poison ivy and poison oak, containing the same poison, are in the same plant family (Anacardiaceae) as mango.

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