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Durian

Description

durianDURIAN

Durian (Durio zibethinus Murray) is a highly valued and most desired seasonal fruit in Mindanao. It is best described as smelling like hell and tasting like heaven. The plant is a large, buttressed tree that grows to a height of 30-40 m but vegetatively propagated plants can only grow to half the height. Seventy-two to 87% of the roots are found on the top 45 cm of the soil, while 85% is within the canopy radius of the tree. The trunk is usually straight and has low branches and a dense canopy. The wide leaves have dark green upper surface that is glossy and densely reticulate. The lower surface is densely covered with silvery or golden colored scales with a layer of stellate hairs. Large flowers hang in huge inflorescences on bare branches and are open at night. Fruits are green to brownish, large, long-peduncled, round to oblong, and have thick, spiny rind and five segments. Each segment contains a yellowish white to yellow, sweet, aromatic aril enclosing 1-4 light brown seeds.
(Source: Philippine Council for Agriculture Aquatic and Natural Resources Research and Development (PCARRD)-DOST, Date accessed 20 March 2014)

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Cultural Management

 

Methods of Propagation

Plant propagation can be by seed, but for uniformity, smaller stature, and early maturity, it is better to use clones produced by asexual methods such as grafting and budding. Seeds are sown immediately after extraction without the necessity of prior drying. Overdrying will in fact tend to kill the embryo because the seed is recalcitrant.

The recommended method of budding is patch budding. Grafting techniques used are inarching, cleft grafting, hypocotyl grafting, and epicotyl grafting. The seedlings can be outplanted after about one year, or further extended to three years in the nursery to produce large planting materials (LPM). LPMs have better chance of survival and the trees mature earlier.

(Source: Crop Agriculture Review, Date accessed: 20 March 2014)

Land Preparation

The land is prepared for planting by first clearing and removing stumps, followed by plowing and harrowing two times. If the soil is too acidic, it can be corrected by applying agricultural lime. But with staggered planting, plowing and harrowing can be dispensed with and only the immediate peripheries of hills are cultivated.

(Source: Crop Agriculture Review, Date accessed: 20 March 2014)

Holing and Planting

Holes at least 50 cm deep and wide are dug 8-12 m apart. Close spacing may neccesitate thinning after 8-10 years to disperse the trees. These spacings correspond to a planting density of about 70-156 plants per hectare in square system or 80-180 in triangular planting.

After holing, the removed topsoil is mixed with compost and used to partly refill the hole. A small amount of lime is added to the mixture if the soil is too acidic. However, the addition of compost during planting is not absolutely necessary for plant establishment.

The seedling is carefully laid on the hole with the potting container removed. The depth of planting should be such that the root crown is in line with the level of the land. More soil-compost mixture is then added and slightly pressed to eliminate air spaces. Water is immediately applied. But in places with irregular rainfall and which are not easily flooded, it is better to leave a slight depression around the seedling to trap water.

Planting should be done at the start of the rainy season to ensure availability of water. The plants should be provided with shade for two weeks or until they are fully established.

(Source: Crop Agriculture Review, Date accessed: 20 March 2014)

Weeding and Fertilization

Regular weeding should be done to eliminate competition for water and nutrients. Thick undergrowth under the canopy of trees will also increase relative humidity near the trunk which favors the reproduction of pathogens. To avoid injury to the roots, the soil should not be scraped. Weeds below the canopy can be totally eliminated by hand pulling.

In addition, the formulation of a fertilizer management program is important in growing durian. The program should ensure the vigor of trees with sustained capacity to produce quality fruits.

Fertilizers should be applied based on soil analysis. In the absence of soil analysis, 50 g of complete fertilizer may be applied during planting. The rate of fertilizer is correspondingly increased with the age of the plants, to be applied during the onset of the rainy season and when it is about to end. Otherwise, fertilization can be done periodically in 2-4 applications per year. Ring weeding should be done before fertilization.

To ensure a steady supply of micronutrients, it is desirable to incorporate the application of organic feritlizers with the fertilization program. Based on the number and average weight of fruits per tree, the amounts of urea (46-0-0), complete fertilizer (14-14-14) and muriate of potash (0-0-60) to be applied per tree have been calculated. A tree with a fruiting potential of 25 fruits each weighing 2 kg or a total of 50 kg needs fertilizer at the rate of 206 kg 46-0-0, 143 kg 14-14-14 and 308 kg 0-0-60 which is increased to 1652 kg, 1142 kg and 2466 kg, respectively, for a tree that produces 200 fruits weighing a total of 400 kg.

(Source: Crop Agriculture Review, Date accessed: 20 March 2014)

Water Supply, Drainage and Mulching

Water should be supplied daily to the newly planted seedlings until they are firmly established. Thereafter, watering is done periodically to ensure that the plants are not subjected to water stress especially during drought. Water is especially needed during the flushing period and from floral induction to fruit development stages. Prolonged drought may be fatal to the plants.

To minimize rapid drying of the soil during dry season, mulching is practiced. This involves the laying of rice straw, uprooted grasses, coconut husk, or any other mulching material on the ground around the durian trees. Mulching on the undercanopy should be avoided during the rainy season.

It is also important that the durian orchard is provided with drainage canals to remove excess water during the rainy season and to reduce the incidence of Phytophthora. Standing water can increase relative humidity which favors the growth of pathogenic organisms. Disease inoculum can spread from tree to tree when there is surface runoff.

(Source: Crop Agriculture Review, Date accessed: 20 March 2014)

Pruning of Durian

Proper pruning is one of the least considered activities but should be made an integral practice in growing durian. Formative pruning is practiced during the first years following planting. This is done by removing excess trunks, upright branches and water shoots, as well as thinning of the horizontal branches. Only a single trunk should be allowed to develop. Removal of excess branches will favor maximum penetration of sunlight and promote air circulation.

The trees may also be top pruned at a height of about 5-10 m to limit the tree height. Likewise, removal of branches 1-2 m from the base of the trunk will help prevent the incidence of diseases as well as facilitate movement. Diseased branches should be removed immediately and burned.

(Source: Crop Agriculture Review, Date accessed: 20 March 2014)

Insect Pest and Disease Control

 Plants Parts/Stage of Growth AttackedControl Measures
Insects  
1. Beetles Young seedlings Spray with Roxion and Azodrin
2. Twig Borers Young plants, small branches or twigs of old trees Plrune damaged branch and burn
3. Psyllids New shoots and leaves in young and old trees Spray with Roxion, Azodrin or Decis
4. Brown Scale Young shoots and leaves Spray with Roxion or Azodrin
5. Haplaphalorasp (Bao-bao) Young shoots, leaves, unopened flowers and fruitlets Spray with Decis, Roxion or Gusathion
Diseases  
1. Path canker or Stem canker Roots, trunk Spray with Ridomil or Alliete
1. Pink diseases Twigs and smaller branches Spray with Tridemorph (Calixim); Triadimefon (Bayleton); Copper hydroxide (Kocide) or Bordeaux mixture
1. Rhizoctonia Foliage Spray with Triamefon-Bayleton, Thiophanate methyl (Topsin M)

(Source: Bureau of Agricultural Research, Date accessed: 20 March 2014)

Harvesting/ Post Harvest Management

Mature fruits should be harvested during sunny days. Extreme care must be exercised to prevent bruising. The following indices are used in determining the right time to harvest:

  1. Depending on the variety and elevation, the fruit has reached minimum days of development starting from flower bloom.
  2. Fruit color turns yellowish-green or brown.
  3. The sutures between adjoining fruit segments are distinct.
  4. The tip of the spikes turn darker brown than the bases.
  5. The tips of the spikes are pliant.
  6. The fruit when tapped has a dull and hollow sound.
  7. The fruit emits a strong aroma.

A well cared durian tree starts bearing fruits as early as five years old. Durian fruits generally fall from the trees at night when already mature and ripe.

Handpicked fruits have longer shelf life of
5-7 days compared to 2-3 days for fallen fruits.

(Sources: Crop Agriculture Review, Date accessed: 20 March 2014)