A mango tree can cover itself in flowers and still give you almost no fruit.
In mango, the season is won or lost at flowering:
the trigger that starts it, the weather while it lasts, and the pests and diseases that attack the flower clusters.
In this video: what makes a mango tree flower, how to prepare the tree after harvest, the flower cluster and its pollinators, alternate bearing, the main threats at flowering, powdery mildew, anthracnose, hoppers and malformation,
why trees flower but set few fruit, and spraying safely around bloom. The advice is general and global.
Your local extension service and the product label always come first.
Mango is a tropical and warm subtropical tree, grown roughly between twenty-five degrees north and south of the equator. Its flowering is triggered by dryness.
Published horticultural literature describes the best mango climate as several wet months followed by roughly eight months of dry season.
Rain discourages flowering, while dryness, and a moderate cool spell where the climate allows one, encourage it.
So work with the trigger.
Water a young tree regularly while it establishes.
But for a mature tree, stop or sharply cut watering in the weeks before your local flowering season, even if the soil looks dry.
Flowering commonly follows several weeks of real dryness and,
where they occur, cooler nights.
The same dry-season trigger explains why growers in some regions spray potassium nitrate to force flowering out of season.
It was a published discovery of nineteen seventy-four,
and it now supports year-round mango supply in several producing countries.
Follow your local advice before trying it.
Flowering care starts right after the previous harvest.
Prune once a year, straight after harvest, not just before flowering.
Remove dead, diseased, crossing and crowded branches,
and cut back overly tall growth, so light and air reach the inside of the canopy.
Remove old flower clusters, dead twigs and mummified fruit too, because they carry over powdery mildew and anthracnose.
Feed the tree once a year, after the main harvest and before the next flowering season. Spread the fertiliser in a ring under the outer edge of the canopy, where the feeding roots are, not against the trunk, and add well-rotted manure or compost.
And avoid heavy nitrogen and irrigation that push a flush of soft new growth at flowering, because that growth is highly susceptible to powdery mildew.
On young grafted trees, remove any flower clusters in the first two years. Letting a very young tree fruit early weakens its framework.
A mango flower cluster, the panicle, is a branched spray at the tip of a shoot, carrying hundreds to thousands of small cream or pinkish flowers.
Most of them are functionally male and were never going to become fruit. That is completely normal.
The flowers are pollinated mainly by small flies and other insects,
not mainly by honeybees.
So protect them. Avoid spraying anything with a broad effect on insects during the flowering window, because it kills the very insects the crop depends on.
Expect only a small share of the flowers to set fruit,
and some natural drop of young fruit in the weeks after. From flower opening, most varieties take roughly one hundred to one hundred and fifty days to reach a fruit ready to pick.
Many mango varieties carry a huge crop one year and almost nothing the next. This is called alternate, or biennial, bearing.
It is a natural rhythm, not a disease.
A heavy crop delays new shoot growth after harvest, so the shoots are too young to flower the next season.
You can soften the swing.
In a heavy year, remove a share of the smallest, most crowded young fruit early. Prune after harvest, and feed the tree well.
Where it is permitted, growers apply the growth regulator paclobutrazol to the soil, which promotes more regular flowering:
use only a registered product, as the label directs.
And when you plant, choose varieties that bear more regularly.
The first big threat at flowering is powdery mildew. It covers flower clusters, young leaves and tiny fruit with a white, flour-like growth.
Flowers and fruitlets drop, and in bad years a tree that flowered heavily sets almost no fruit.
Losses of fruit set of twenty to ninety per cent are reported in susceptible varieties.
It strikes during flowering in cool, dry weather with dewy nights, so protection is timed to the emergence of the flower clusters.
Where the disease comes every year, protective sprays at panicle emergence,
full bloom and fruit set are standard. The groups in Laisha's encyclopedia are FRAC group M two, sulphur, a multi-site protectant that can scorch in heat; group three, the demethylation inhibitors; and group eleven, the quinone outside inhibitors, in mixtures.
Powdery mildews readily develop resistance, so alternate and mix groups with sulphur.
Anthracnose is the most important disease of mango wherever rain,
fog or heavy dew meets flowering or fruiting. It blackens the flower clusters so fruit never sets,
and later rots ripening fruit that looked perfect at harvest.
Manage flowering to fall in the dry season where you can, and keep the canopy open.
Protective sprays run from panicle emergence to fruit set in wet weather. The groups are FRAC M one, copper, and M three, the dithiocarbamates, both multi-site protectants, plus groups eleven and three.
Resistance to group one is widespread in mango anthracnose, so alternate and mix groups.
Scout the flower clusters regularly through flowering.
Small jumping insects on new shoots and flowers, with a sticky coating on the leaves below, are mango hoppers, among the most damaging pests at this stage.
Tight, deformed clusters instead of normal open ones are mango malformation.
It has no cure once established, so remove affected shoots, and never take grafting wood from a tree that shows it.
If your tree flowers well but sets few fruit, the common causes are rain or cold during flowering, few pollinators, powdery mildew or hoppers on the flower clusters, or a high share of male flowers.
You cannot control the weather at flowering. But you can make sure nothing else works against the tree:
no badly timed spray that kills pollinators, no unnecessary watering before bloom, and an open, clean canopy.
When you do spray, read the label first, use only products registered for mango in your country, at the label dose, and respect export residue limits and the pre-harvest interval. Wear gloves and eye protection, mix outdoors, and store pesticides locked, away from food and children.
To recap. Mango flowers after a dry spell, so stop watering mature trees in the weeks before flowering. Prune and feed right after harvest, and clear old panicles and dead twigs.
Most flowers are male, and small flies do the pollinating, so never spray broad-acting insecticides in bloom.
Soften alternate bearing by thinning heavy crops.
Protect the flower clusters against powdery mildew and anthracnose by FRAC group, scout for hoppers and malformation, and follow the label.
For full grow guides and the pest and disease encyclopedia, visit laisha.ai.
And before you go: Laisha Lens number one is out, our free guide to November, for every climate zone on Earth.
North of the equator, the cool-season crops go in:
winter wheat and garlic in the temperate north,
wheat, barley and lentil on the autumn rains of the Mediterranean,
and on the plains of South Asia the whole rabi season,
wheat, mustard, chickpea and potato.
South of the equator it is spring, and the tropical south sows soybean, maize, cotton and rice on the first rains.
Lens also covers crop residue without fire, the pests worth walking the field for, and a study plan for agri students.
Open My farm's November, choose your zone and up to three crops, and it builds your field jobs, week by week, with the pests to scout for. It is free, and needs no account. Our free November Lens, with your farm's month plan, is on laisha.ai slash lens.
From all of us at Laisha: may your fields do well this season. Thank you for watching.
