Nam Doc Mai

The Nam Doc Mai mango variety originated in Thailand and was introduced to Australia in the early 1980s. In Thailand, Nam Doc Mai is the most popular mango variety and generally eaten when soft ripe. It is a major variety of commerce in Asia. In Australia, it is eaten both as a ripe fruit and hard green fruit in Asian recipes.

The fruit quality is excellent, with a pale green/yellow fibreless flesh and a rich, sweet flavour. Nam Doc Mai is grown commercially in many Australian mango-growing districts, but is a minor variety in the Australian market.

Tree characteristics

The Nam Doc Mai tree is of medium-to-high vigour with an upright, dense canopy. The newly emerging leaves are initially light green, turn tan as they expand and become dark green as they mature. The leaves have a characteristic wavy edge. Six-year-old trees can reach heights of 6 m or more and a diameter of 4-6 m if left unpruned.

Flowering characteristics

  • panicle length - 30-40 cm
  • panicle width - 20-30 cm
  • hair density - medium
  • colour - faint pink
  • colour of wilted petals – brown.

Fruit characteristics

  • fruit shape - elongate slightly sigmoid
  • ground colour - green/yellow
  • blush colour - faint pink
  • average weight - 250-400 g (avg 340 g)
  • average length - 130 mm
  • average width - 61 mm
  • average depth - 71 mm
  • lenticel size - small
  • lenticel colour - yellow/white
  • flesh colour - green/yellow
  • skin thickness - thin
  • flesh fibre - low to none
  • firmness - medium to soft
  • stem end shape - elevated
  • beak shape - prominent
  • flesh recovery - 75 per cent
  • flavour - mild and very sweet
  • embryo type – polyembryonic.

Propagation

Nam Doc Mai is a polyembryonic* mango and when planted, the seed will produce several seedlings most of which will produce fruit that is true to type. Trees propagated by grafting will come into production earlier, producing fruit 1-2 years after planting. Seedlings can take up to 5 years to fruit.

* Refer to Glossary

Plant density

Although the Nam Doc Mai tree is of medium-to-high vigour, its upright branch habit allows it to be planted at closer spacings than Kensington Pride. Recommended spacings are 4-6 m in the row and 9 m between rows (185-278 trees/hectare). Closer plantings can be managed, though they require heavy annual pruning to maintain a smaller canopy size.

Pruning and shaping

During the first few years after planting, branches should be tipped after every second flush to encourage the canopy to spread and develop a well-branched frame capable of holding heavy crops in later years. When the tree begins to bear fruit, an annual thinning of the canopy is necessary to reduce foliage density. Dense canopies harbour pests and prevent spray penetration. Topping to keep the tree at a height of 3-5 m and skirting to remove low branches for under tree access should also be carried out annually.

Flowering and fruit set

Nam Doc Mai is a strong, regularly flowering tree in most Australian growing regions. However, in some years, fruit set is a problem and nubbins (fruit without seed) may be produced. Nubbins are either shed during late fruit development or, if held full term, develop to half or three-quarters the size of seeded fruit. Nam Doc Mai is an irregular bearer and tree yields vary greatly from year to year.

Pest and disease status

Nam Doc Mai is more susceptible to the fungal disease powdery mildew than most other varieties. Powdery mildew (Oidium sp.) infects the flower panicles during late flowering and early fruit-set stages, causing the fruit to drop off.

Nam Doc Mai has moderate-to-high resistance to bacterial black spot (Xanthomonas campestris pv. mangiferaeindicae) and is susceptible to post-harvest diseases including  as anthracnose (Colletotrichum gloeosporioides), a major cause of fruit blackening, and stem end rot (Botryosphaeriaspp. and Lasiodiplodia theobromae).

Nam Doc Mai is affected by major insect pests such as mango scale (Aulacaspis tubercularis), pink wax scale (Ceroplastes rubens Maskell), mango shoot caterpillar (Penicillaria jocosatrix), mango tipborer (Chlumetia euthysticha), fruit flies and mango planthopper (Colgaroides acuminata).

Fruit disorders

Nam Doc Mai does not suffer sapburn to the same extent as Kensington Pride; however, the sap will still mark the fruit if left on the skin. Nam Doc Mai suffers from the internal disorder jelly seed. Fruit with jelly seed has over-ripe flesh around the seed when the rest of the flesh is just beginning to soften.

Harvesting and handling

In Australia, Nam Doc Mai is harvested to be eaten both as hard green fruit (green eating) and when ripe. When harvested for green eating, the fruit can be picked at any stage from three-quarters of full size onwards. However, the flavour is best when fully mature. When harvested to be eaten ripe, the fruit should be harvested after the fruit sides have filled out but before the fruit begins to soften. As Nam Doc Mai fruit is very soft when ripe, picking at the firm mature stage prevents damage to the fruit from harvesting and handling operations.

Glossary

Dry Tropics

Townsville, Burdekin and Bowen region

Flushing

Periodic growth

Lenticels

Pores in the skin of the fruit

Monoembryonic

Single embryo in seed, producing a seedling that is a genetic cross between the mother tree and pollen donor

Panicle

Branched flower spike with many flowers

Polyembryonic

Seed with multiple embryos, producing seedlings that are genetically identical to parent tree

Ovate

Egg-shaped

Last updated 16 April 2014