Avocado Fuerte Cultivation Notes for South Africa and Introduction to Mexican and Guatemalan Varieties
If you are very serious about growing avocados, you can buy trees from a nursery. Poor-quality trees will grow slowly in the orchard, no matter how careful you are. Please note the following:
The size of the container in which the plant is grown. Generally, the larger the container, the healthier the root system and the greater the chance of successful establishment.
Growing medium. Clay mixtures tend to clog the drainage holes in plastic containers. Lighter soil improves drainage and stimulates root development.
Leaves. A healthy tree has glossy, dark green leaves with no deformation or discoloration.
Read Growing Avocados: Know Your Soil
Graft union. Grafting combines the tissues of two plants to form a new plant. One plant - the “rootstock” - is chosen for its roots. The other - the “scion” - is chosen for its stem, leaves, flowers or fruit. With avocados, excessive thickening at the joint (the union) or a large difference between the thickness of the rootstock and the scion is a sign of incompatibility, a poor rootstock, or a diseased scion. You should see a smooth union, with little or no irregularity on the stem.
Choosing a Variety
The above are general guidelines. To choose a specific variety, keep climatic conditions in mind. Of the three best-known avocado races, the West Indian varieties are best suited to continuously hot, humid environments with heavy summer rainfall.
They cannot tolerate frost. The optimal temperature for growth is 25°C to 28°C (humidity above 60%).
The Mexican race originated in that country's cool subtropical highland forests, and mature trees can withstand temperatures of -4°C to -5°C.They should not be planted in areas prone to frost in August and September, because the flowers are easily damaged by frost. The optimal temperature for growth is 20°C to 24°C, with humidity of 45% to 60%.
Guatemalan varieties require a cool tropical climate without extremes of temperature or humidity.The flowers are particularly sensitive to frost. High temperatures of about 38°C, especially if combined with low humidity, can cause flowers and fruit to drop. Humidity of 65% or higher is required.
Fuerte is the most commonly cultivated variety in South Africa and is considered a natural hybrid between the Mexican and Guatemalan races, with broader climatic tolerance (especially to cold) than pure Guatemalan types.
The optimal growth temperature is 20°C to 24°C. High temperatures, especially during flowering, are not well tolerated.
All avocado varieties commercially produced in South Africa are sensitive to moisture stress. Planting areas should have annual rainfall above 1 000 mm, evenly distributed, with June and July being only a dry period. However, most suitable areas in South Africa experience dry weather during flowering and require supplementary irrigation. From a climatological point of view, the best areas for commercial avocado production are the cool subtropical regions of Mpumalanga, Limpopo and KwaZulu-Natal, where rainfall is fairly high and fog occurs frequently.
High humidity (above 50% at 2 p.m.) is ideal, because it reduces stress conditions, especially high temperatures. This plays an important role during flowering and fruiting. The fog belt areas of South Africa are particularly suitable.
