The Sunday Mail
IT is surprising that one of the most flourishing crops in the country is not enjoyed by most Zimbabweans.
The macadamia horticultural sector continues to grow with most of the produce being exported.
Perhaps it is time that we as Zimbabweans start enjoying this tantalising nut crop packed with flavour and pleasure.
Macadamia intergrifolia is an Australian evergreen tree in the protea family reaching 15 metres in height.
The tree bears seeds with a hard shell concealing the edible kernel inside.
Though it is grown as a commercial crop, there is no reason why one cannot plant a few trees in a garden.
As gardeners, our enjoyment is not only in eating the fruit but also in seeing the tree grow under our careful watch.
Macadamia trees are normally grafted on to another species of Macadamia (tetraphylla), which is a better rootstock as its seeds germinate uniformly and is resistant to Phytophthora infections.
Tetraphylla also encourages early fruiting of macadamia intergrifolia scion.
To germinate seeds for the rootstock, pick them from the ground and remove the husk (outer coat).
The seeds should be planted immediately and not stored for more than half a year. An alternative is to remove the hard seed coat by heating the seeds at 27°C for two weeks and ensure that the kernel is not damaged.
Plant the seeds pointing downwards about 5cm deep or less.
Germination usually takes two to 12 weeks.
The seedlings are ready to be grafted when they reach 10-18cm in height.
Some cultivators of macadamia that have proved successful are “Elimbar”, “Ikaika”, “Kakea” and “Keaau”.
Macadamia trees will flourish where rainfall is above 1 000mm and temperatures do not drop below freezing point and in Zimbabwe it is widely grown in Nyanga, Chipinge, Chimanimani and Marondera.
However, the soil must be well-drained and a neutral pH7 is ideal.
Erect wind breaks where wind speeds are high as the tree is very brittle. Fertilisers can be applied three to four times a year, based on soil analysis results, paying particular attention to micro-nutrient deficiencies such as iron, magnesium and zinc, though the tree will do well with a single application of compound X in a year.
Grafted trees can be planted into the orchard after a year at a spacing of eight metres by eight metres if a square layout is used.
Train the trees to a central leader system as in apples.
Watch out for termites before the trees begin fruiting.
The tree will start to bear fruit in the fifth year and can bear nuts for as long as 40 years.
Expect flowers after the winter season and flowering may last for a month or two. Count 212 days to the maturing of nuts, which will fall to the ground when ripe, usually from March to April.
Each tree is expected to yield 5-8kg, and this may increase up to 40kg per tree in the 11th year, amounting to 7 500kg per hectare.
A tonne of the nuts can be sold for as much as US$2 000 to US$3 000.
Ripe nuts are picked from the ground so ensure that the floor is kept clean.
After harvesting, dry the nuts to 1,5 percent moisture content, then begin the shelling process which can be done by hand or machine.
Nuts can be cooked in coconut oil and vacuum packed. Rats and other small animals can cause losses and thus must be controlled.
There are not many insects and diseases to worry about except for the green vegetable bug and anthracnose or phytophthora infections.
Macadamia nuts are used in baking, confectionery, ice-cream and the snack food industry, whilst the macadamia oil is used to make skin care products.
Research has also proved that regular consumption of macadamia will reduce the risk of heart disease.
For further details contact the writer by email at [email protected]
