Guide on managing bearing mango trees

By Baby P. Ramilo, Agriculture magazine (12.2005)

Here's a guide recommended by the National Research and Development Center (NMRDC) in Guimaras on the proper cultural management of bearing mango trees.

Pruning

Pruning is the removal of undersirable vegetative parts of the tree, including dead, insect-infested, diseased and crowded branches (referred to as light pruning). It is done to allow sunlight to penetrate the crown, reduce incidence of pests and diseases, improve quality of fruits, increase fruit production and make the trees resistant to lodging.

The best time to prune is during summer after harvest to prepare the tree for the next bearing season. At the same time, pruning in summer favors faster healing of wounded plant parts.

An integral part of pruning is training the canopy to a manageable size, shape and height. If possible, pruning on the sides should be avoided. Drastic pruning (topworking), on the other hand, can be used only to change the variety or rehabilitate old, non-productive trees.

Irrigation

Irrigate the trees weekly during flower initiation and fruit development stages up to one month before harvest. Adequate water supply will enhance fast development, minimize fruit drop and increase fruit size. The volume of water ranges from 60-100 liters per tree, depending on the size of the tree and available soil moisture.

Fertilization

As much as possible, soil/tissue analysis should be done to determine the nutrient requirement of mango trees. In the absence of such, the following rates are suggested:

  • 5-6 years old:  500 gm-1 kg 14-14-14 (triple 14) or 3-4 kg manure + 500 gm-1 kg triple 14
  • 7-8 years old: 2 kg triple 14 or 4-5 kg manure + 2 kg triple 14
  • 9-10 years old: 3 kg triple 14 or 5-6 kg manure + 3 kg triple 14
  • 11-15 years old: 5 kg triple 14 + 10 kg manure
  • 16-20 years old: 6-7 kg triple 14 + 12 kg manure
  • Above 20 years old: 10 kg triple 14 + 15-20 kg manure

Apply fertilizer on the soil once or two times (split) at the onset and before the end of rainy season. Fertilizer can also be applied during the dry season if there is enough irrigation.

Place fertilizer in canal dug around the tree with 1-2 meters radius from the trunk and 15-30 cm deep or in 6-8 holes around the tree. For big trees, follow the canopy drip line.

At flowering, spraying of foliar fertilizer is also recommended as suppllement.

Flower Induction

Potassium nitrate (KNO3) is the generic name of the chemical flower inducer used in mango. This contains 13% nitrogen and 46% potash. When sprayed on mango, it supplies the potassium requirement of the tree and helps induce flowering.

Before inducing mango trees to bear flower, the following should be considered:

  1. Varied flowering and fruiting habits of different varieties of mango.
  2. Chemical flower inducers should not be used when the tree is too small or too young, when the leaves and buds are young, when the tree is sickly, during rainy days and after harvest or when the tree has fruits or at the flushing stage.
  3. High dosage (2.0-3.0%) should be used when the weather is cold/cloudy, when trees are just starting to mature or having vigorous buds and leaves.
  4. Low dosage (1.0-1.5%) of inducers is used during sunny or hot weather, when trees are big, old or fully mature and when trees are healthy with dormant buds.
  5. Induce flowering only once a year.
  6. Age of shoots should be 7-8 months (from flowering to harvest).
  7. Trees that had borne fruits last season but have not flushed should not be induced to flower.
  8. Spray when the tree and leaves are dry and with no expected rain within the next 6 hours.

Spray KNO3, by thoroughly wetting the leaves but not dripping. Spray early in the morning (from sunrise to 9:00 AM) or late in the afternoon (from 4-5 PM) to prevent leaf burning due to direct sunlight.

Management at Flowering Stage

Supplement solid fertilizer with liquid fertilizer (foliar) at 14-18 and 22-25 days after flow induction (DAFI).

Control of important insect pests and diseases should be done. Spray insecticide/fungicide only when necessary.

Encourage pollinators (flies and bees) by withholding pesticides at full bloom (28-32 DAFI). A 10% sugar solution is recommended to attract poliinators.

Irrigate the trees weekly to enhance vigorous development of flowers.

Management at Fruit-Bearing Stage

Foliar fertilizer is applied at fruit set (35-40 DAFI) and fruit development (50-55 DAFI).

Pest control against major insects and diseases is necessary. Bag (paper) the fruits at 55-60 DAFI at which they are about the size of chicken egg. This practice minimizes incidence of fruitfly and other insects, minimizes fungal and other disease infection, reduces mechanical damage and results in cleaner fruit skin. Generally, this will minimize the use of pesticides.

Irrigation is applied weekly during fruit development and stoppped one month before harvest.

Pests and Diseases

Flowering stage
Insect pests - leafhoppers, tip borers, scale insects/mealy bugs, thrips, flower beetles
Diseases - anthracnose, die back

Fruit-bearing stage
Insect pests - mango seeds black borer, fruitflies, cecid flies, helopeltis, scales, mealy bugs, pulp weevil (in Palawan)
Diseases -anthracnose, diplodia, scab, sooty mold

Integrated Pest Management

Integrated pest management for mango involves the following practices:

  1. Practice of clean culture which includes pruning, weeding, thinning, cultivation and burning/destruction of infested branches and fruits.
  2. Regular monitoring of pest population.
  3. Using only approved insecticides/fungicides for mango.
  4. Application of pesticide only when necessary using the recommended dosage and proper timing.
  5. Introduction and maintenance of natural enemies and other biological control methods.
  6. Maintaining of right soil pH of 6-7 by applying recommended fertlizers and soil conditioners.
  7. Using pesticides derived from plant extracts.
  8. Combinantion of cultural, chemical and biological control methods to minimize pests.

 Harvesting

The following are the indications that mango fruits are ready for harvesting:

  • At 110 days (for very warm and dry environment), 120 days (warm climate) and 130 days (cool and high elevation) after flower initiation;
  • Broadening of shoulders at the stem end and fullness of cheeks;
  • Pedicel turns dark green to brown and pulp turning yellow;
  • Presence of powdery deposit or "bloom" on the surface of the skin; and
  • Sinking of 75% mature fruits when submerged in 1% solution (100 gm salt to 1 liter of water).

Methods of Harvesting

Fruits are either picked by hands or by means of picking pole and harvesting tools. Harvesting by hand, however, is more effective in order to minimize bruises or damage on the fruits. The best time to harvest is between 9-3 PM when the latex flow is minimal. This will be trimmed and dried before packing.

Postharvest Treatments

The following postharvest treatments are recommended when opting to sell high quality fruits:

  • Washing of fruits in water. The fruits are washed in water to remove dirt on the surface.
  • Hot water treatment. The fruits are dipped in hot water (52-55°C) for 5-10 minutes followed by hydro-cooling (washing in cool water) and airdrying.
  • Vapor heat treatment. This involves heating the fruits with water vapor saturated air until the fruit pulp temperature reaches 46°C for 10 minutes.

Packing

Sort fruits as to marketable and non-marketable in terms of size and quality. Bamboo baskets (kaing) lined with newspapers are used in packaging mangoes intended for local market. For export market, mangoes are packed in plastic crates or carton boxes with individual compartments.

Ripening of Fruits

There are two ways to induce faster ripening of mango fruits:

  • Calcium carbide or "kalburo". Best results are obtained by allowing the fruits to ripen naturally (half ripe, with tinge of yellow color) prior to treatment with calcium carbide at the rate of 1.25 gm per kilo of fruit. This is done by wrapping the calcium carbide with paper or leaves and placed at the bottom of the container and covered for 2-3 days.
  • Ethyl water solution. The fruits are dipped in the solution for 3 minutes to accelerate ripening.