THE Avocado ( Persea Americana Miller) is an evergreen tree of the family Lauraceae with seedling plants reaching 67ft (20m) in height with large, single-seeded fruits having yellow to yellowish green butter-like flesh. Mature fruit vary in colour and may be green, yellow, purple or red.

There is always a great demand for avocado plants and the National Agricultural Research and Extension Institute (NAREI)’s Plant Nurseries are always trying to meet the demands of farmers. Although there are seedling trees around, avocado plants are commonly grafted as this reduces the time taken for bearing, combines the best characteristics of varieties and improves resistance/tolerance to diseases.

Fruits are collected from healthy, vigorous, mature trees and deseeded; the seeds are washed, dried and sown individually in black plastic bags, broad side down and covered with not more than 1 inch (2.5cm) of soil. Grafting is done when plants have attained a height of about 1.5ft (0.5m). Wedge grafting is the type commonly used. The scions for grafting are collected from healthy, vigorous, mature trees having desirable traits e.g. fruit size, flavour and shape. The graft is wrapped securely and covered with clear plastic until it catches. This is seen if graft remains green and buds start to burst into leaf after 2-3 weeks.
During this entire process the plants should be protected from severe sunlight and receive adequate water until transplanting in field. Avocado plants are ready for planting out in the field approximately six to nine months after grafting. Site Selection Avocado can be grown on a variety of soils, but it does not thrive on the coastland. Nevertheless, wherever the avocado is planted there is need for good drainage since its shallow root system makes it sensitive to poor drainage and water logging.

There are numerous varieties of Avocados, but they all have either of two flowering patterns– ‘A’ or ‘B.’ The ‘A’ type flowers are those which show receptive female parts in the morning and receptive male parts in the afternoon of the following day. The ‘B’ type flowers show receptive female parts in the afternoon and receptive male parts in the morning of the following day. With this mechanism the female parts of the ‘A’ type flowers are thus receptive to pollen from the ‘B’ type flowers in the mornings, whilst the female parts of the ‘B’ type flowers are receptive to pollen from the ‘A’ type flowers in the afternoon. Avocado is not commonly self-pollinated; therefore it is important to encourage cross-pollination by having ‘A’ and ‘B’ type trees in the orchard or backyard.

Planting should be done during the wet season while there is an adequate supply of moisture for quick establishment of roots. When planting, the vigour and growth pattern of the trees should be considered. Those that have a spreading habit would require more space than upright types. Generally, plants are spaced 20-25 ft apart (6-7.5m) giving approximately 100-70 trees/acre (250-175 trees/ha).

In areas where there is no water-logging, planting holes are dug to a size that would accommodate the plant in the bag. The size of the hole should therefore be around 1ft (30cm) in length, width and depth. The roots of bare-root plants are more spread out and a larger hole will have to be made to accommodate these plants. The topsoil removed in digging the hole could be mixed with rotted manure and/or some phosphate fertiliser.

Some of the soil is then returned to the hole, filling about half way up. The plastic bags are carefully removed to keep the root ball intact and the plants are placed in the holes. The balance of the topsoil is then returned to fill the hole and thoroughly compressed. The plants should then be watered. After planting, it is recommended to stake the plant to prevent movement by wind. In areas where water-logging is suspected, the same system is used except that planting is done on mounds.