Instructions for watering Mango trees

Watering mangoes needs to be based on tree age, season and growth stage. Instructions on water quantity, irrigation distance, water drainage and water management in salinity drought areas for mangoes in the Mekong Delta.

Summary: Mangoes are more drought-resistant than many other fruit trees, but productivity and fruit quality still depend greatly on irrigation. Lack of water during flowering causes the flowers to dry out, lack of water during fruit growing causes small fruits, and waterlogging causes root failure and fruit loss. This article provides instructions on how to water a commercial mango orchard according to tree age, season, and drainage.

Applies to: Hoa Loc mango, Cat Chu mango, Taiwanese mango, Keo mango in the Mekong Delta, Southeast and lowland areas.
Duration: Water management all year round, adjusting according to the dry/rainy season and flowering — fruit growing period.
Difficulty level: Basic to moderate.
Estimated additional costs: 5-25 million VND per hectare if installing sprinkler irrigation around the base or upgrading drainage ditches.

Principles of watering mango

Watering mangoes is not always "the more the better". Plants need different water in each stage:

Seedlings: need even moisture to root and bud.
Plants preparing to flower: need controlled, gentle drying to differentiate flower buds.
Blooming stage: needs stable humidity, avoid dry shock/water shock.
Fruit growing stage: needs enough water for the fruit to grow, but not waterlogged.
Before harvest: moderately reduce watering to enhance fruit flavor and limit cracking.

The goal is to keep the moisture stable around the root zone, not let the soil dry out and crack and then water deeply.

Amount of water according to tree age

The tree has only been planted for up to 1 year

Dry season:

Irrigate 9-12 liters per root each time.
Irrigate once every 2-3 days.
Cover the base with straw, hay or rice husks to retain moisture.

Rainy season:

If it rains more than 5 millimeters, irrigation is usually not needed.
If there is little rain, check the soil every 2-3 days.
Do not let water accumulate in the planting hole.

2-3 year old tree

Dry season:

Irrigate 20-30 liters per root each time.
Water once every 2-3 days if the soil is sandy or the sun is strong.
Water every 3-5 days if the soil is well moisturised.

At this stage, the tree is creating a canopy. Lack of water causes slow sprouting and uneven spread.

Business tree

For fruit-bearing trees, the amount of water depends on the canopy and the soil:

After harvest recovery: water evenly to produce new shoots.
Before flowering treatment: reduce watering for 15-25 days if necessary to create mild drought.
When flower buds appear: water slowly, do not water suddenly.
Fruit cultivation: maintain stable moisture, especially 30-60 days after fruit set.

Do not use a fixed watering schedule for the whole year. The schedule must change according to the tree stage.

Spray irrigation around the root

Spray irrigation around the roots is suitable for mango orchards because:

Save water rather than overflow irrigation.
Reduce pipe pulling effort.
Water is evenly distributed around the root zone.
Less erosion of the surface.
It is possible to combine fertilization through the system if designed correctly.

Notes when installing:

The sprinkler should cover the area under the canopy, not just close to the trunk.
Do not water the stem continuously because fungus can easily develop.
Check for clogging every week.
Divide irrigation areas for even water pressure.

With a new orchard, irrigation should be designed from the beginning. Repairing after the tree has grown usually takes more effort.

Water according to growth stage

After harvest

The tree just lost its strength after the fruit harvest:

Water with enough moisture for the plant to bud and recover.
Combination of organic fertilizer and balanced NPK.
Do not let the plant dry for too long as it will cause weak buds.

Before flowering

When the leaves are completely old, watering can be reduced so that the plant receives the signal to differentiate flower buds:

Stop or reduce watering for 15-25 days depending on the soil.
Do not let the plant wilt severely.
If the leaves droop a lot in the early morning, water lightly.

Slight drought helps stimulate flowering. Excessive drought causes plants to decline and flower poorly.

Flowering and fruiting

Water lightly and evenly.
Avoid spraying water directly on flower clusters.
Do not let the soil dry suddenly.
Do not water thoroughly after many dry days because the flowers/young fruits will easily fall off.

Raising fruit

This is the stage where stable water is needed:

Irrigate according to soil moisture, not according to the feeling of looking at the surface.
If the soil under the root layer is still moist, it doesn't need to be watered much.
If the sun lasts a long time, increase the watering frequency but divide the amount of water into smaller amounts.

Lack of water at this stage makes the fruit small, thick-skinned, and of poor quality.

Drainage of water in the rainy season

Mangoes do not like prolonged waterlogging, especially when flowering or bearing fruit.

Plain orchard

There should be embankments and ditches inside the orchard.
The ditch must be clear, do not let grass/water hyacinth block the stream.
After heavy rain, check to see if the water recedes within 24 hours.
The water intake must be able to open and close when the tide/salinity changes.

If the orchard is flooded while the trees are flowering or bearing fruit, yield loss will be very severe.

Hill orchard

Plant along contour lines if the land is sloping.
Make drainage ditches between rows.
Do not let the water flow too fast to erode the roots.
Cover the roots to retain moisture but do not cover the root neck.

Water management in drought and saline areas

Areas at risk of salinity need three more things:

Measure salinity before pumping water into the ditch.
Close the drain when salt water is high.
Save fresh water when there is good water.

Mangoes are more tolerant of salt than some sensitive fruit trees, but young trees, flowering trees and fruit-bearing trees are still very susceptible. When salt water exceeds the plant's tolerance level, only water sparingly to prevent wilting, do not water too many times as salt accumulates on the surface of the bed.

Monitor soil moisture

Can still test without expensive equipment:

Use your hands to squeeze the soil to a depth of 10-20 centimeters.
The soil is clenched into a ball, gently squeezed and broken: good moisture.
Loose soil, not cohesive: dry.
The soil is sticky and has an anaerobic smell: too wet.

If possible, use a soil moisture sensor to adjust irrigation more accurately, especially in large orchards.

Common mistakes

Spill watering quickly: wastes water, washes away manure and easily erodes soil.

Water vigorously after many dry days: the plant will be shocked by water, easily losing flowers/young fruits.

Not draining water in the rainy season: roots lack oxygen, leaves turn yellow and fruit falls off.

Not measuring salinity before pumping: bringing salty water into the ditch, which is then very difficult to handle.

Use a year-round watering schedule: plants need different amounts of water at different stages.

Take notes

[ ] Irrigation date, amount of water or irrigation time.
[ ] Water source and salinity if any.
[ ] Rain in the orchard: days, estimated rainfall.
[ ] Trees stage: after autumn, flowering, fruit setting, fruit growing.
[ ] Soil condition: dry, moist, waterlogged.

After a few crops, a watering diary will help you know how much water your orchard really needs and avoid watering out of habit.

References

*Instructions for watering mango trees* — Hainong technical document.
*Measures to limit the harmful effects of salinity on fruit trees* — National Agricultural Extension Center.
*Technical process of mango cultivation* — Southern Fruit Institute.