Avocado Production in Asia and the Pacific - United Nations in ...

short dry period with intermittent rains, rather than during the long dry period after the Maha
season. Under supplementary irrigation, however, avocados can be easily established at any
time of the year. Some amount of shading is necessary during the period of planting to
provide the necessary growing environment to young plants.
4.3 Spacing
Earlier recommended spacing of 11.5 x 11.5 metres has now been reduced to 8 x 8
metres as new grafted varieties need much less spacing. In fact, new dwarfing rootstocks
have now been developed in California, Florida and Israel that require even less spacing.
This gives an advantage of increasing the plant density from 100 plants/ha to 170-180
plants/ha and even more. Planting density also depends on the orchard layout. Conventional
systems for avocados grown on flat land include the rectangular, square, triangular,
quincunx, and the avenue planting systems. On sloping land, it is recommended that orchards
be established on the contour planting system where competition between trees is minimized.
4.4 Opening of pits and planting
The size of the planting hole is generally 60 x 60 x 60 centimetres. The holes are
filled with equal parts of topsoil and compost. As most of the wet zone soils are acidic, pH
adjustment (to 5.5 - 6.5) is achieved by applying Kiesarite or dolomite, according to the
recommendations of the Department of Agriculture. At the time of planting, or 2-3 weeks
after planting,450 grams of fertilizer mixture are applied per hole. Grafted plants are placed
in planting holes with the graft union kept about 30 centimetres above ground level. Plants
are staked to prevent breakage from winds and are kept tied until the tree is firmly
established.
5. MANAGEMENT OF ORCHARDS
5.1 Training and pruning
Training and pruning is not an adopted practice in home gardens. In large-scale
cultivations, however, training and pruning are adopted, as they give closer spacing (8 x 8 m)
to allow maximum coverage of land. As a first step in pruning, the main stem is cut back at a
height of 60 cm from the ground, to encourage formation of lateral branches. A maximum of
3-4 healthy lateral branches are allowed around the trunk and the rest are removed. Up to
flowering (3-4 years), the basic framework is developed with a modified central leader
system. After bearing commences, no pruning is effected. In case of excess vegetative
growth, however, a mild pruning is carried out just after harvesting. In addition, all weak
branches and diseased shoots are removed annually.
5.2 Application of manures and fertilizers
Two applications of NPK (N:P 2 O 5 :K 2 O - 12:14:14) is the general practice in largescale
cultivation. These are applied at the onset of the southwestern Yala and northeastern
(Maha) rains. The amount increases with the age of plants, starting from 0.5 kg/year in the
first year and increasing up to 3 kg/year. After bearing commences , 3 kg/year is the
recommended amount per tree. Though compost is recommended in addition to NPK, largescale
growers seldom adopt this practice. In contrast to large-scale cultivation, application of
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