Overview
Sclerocarya birrea (A.Rich.) Hochst. subsp. multifoliolata (Engl.) Kokwaro is a tree species native to Africa. Commonly known as the Marula tree, it has been traditionally valued for its medicinal properties, as well as for its nutritious and flavorful fruits, which have made it popular in food and beverage production.
Origin and Distribution
The Marula tree is endemic to sub-Saharan Africa and can be found throughout the continent's savannah woodland, and on the edges of the Kalahari desert. It is most abundant in South Africa, Zimbabwe, Namibia, Swaziland, Botswana, and Mozambique.
Physical Characteristics
The Marula tree is a medium-sized deciduous tree, which can grow up to a height of fifteen meters. It has a broad and spreading canopy, with a dense treetop that provides ample shade. The bark is smooth and grey in color, and the leaves are pale green, large and compound, with up to 40 leaflets in a single leaf. The tree produces small, cream-colored, fragrant flowers, which bloom from August to November. The fruits are sub-spherical drupes, about the size of a large plum, with a greenish-yellow skin, and a hard, woody shell inside.
Traditional Uses
The Marula tree is a plant with numerous traditional medicinal uses for various ailments. The bark and roots are used to treat dysentery, diarrhea, hemorrhoids, and rheumatism. The stems and twigs are used to treat malaria, syphilis, and fever. Additionally, the tree's fruits are rich in vitamin C and have a pleasant flavor, which lends itself to diverse culinary uses. The juice from the fruit is fermented and distilled to produce a potent alcoholic beverage known as Marula liqueur, which is used for cultural and social events in parts of sub-Saharan Africa. The oil extracted from the nuts is also used in cosmetic production, as it contains high levels of antioxidants and fatty acids, and is known to protect and nourish the skin and hair.
Light Requirements
The Sclerocarya birrea (A.Rich.) Hochst. subsp. multifoliolata (Engl.) Kokwaro plant requires full sun exposure to thrive and produce a bountiful harvest. Therefore, it is ideal for planting in areas where there is plenty of sunlight and an adequate amount of heat that allows photosynthesis to take place conveniently.
Soil Requirements
Sclerocarya birrea (A.Rich.) Hochst. subsp. multifoliolata (Engl.) Kokwaro grows best in well-draining soil with a pH of 6.5 to 7.5, which should be fertile and rich in organic matter. The soil should also be porous enough to allow adequate air circulation to the roots for optimal growth. Additionally, this plant type can tolerate a wide range of soils, including loam, sandy-loam, and gravelly-loam soils that are deep and well-drained.
Temperature Requirements
The Sclerocarya birrea (A.Rich.) Hochst. subsp. multifoliolata (Engl.) Kokwaro plant typically grows in warm and hot climates. It requires a minimum temperature of around 20C to thrive and grow to maturity. However, the plant can tolerate higher temperatures of up to 45C in regions with hot and arid climatic conditions. It can grow in regions with low amounts of rainfall, although irrigation is essential during the early stages of growth.
Cultivation Methods
Sclerocarya birrea (A.Rich.) Hochst. subsp. multifoliolata (Engl.) Kokwaro, commonly known as the African marula tree, is mostly propagated through seeds. The seeds need to be sown in well-draining soil, and the planting hole should be deeper than the size of the seed. The tree grows well in both sandy and loamy soils and requires plenty of sunlight.
Watering Needs
The African marula tree is drought-tolerant and does not require regular watering. However, young trees need to be watered regularly, especially during the dry season, to help establish their root systems. It is advisable to water the tree deeply but infrequently, allowing the soil to dry out before the next watering session, to prevent root rot.
Fertilization
The African marula tree is a heavy feeder and requires regular fertilization to promote healthy growth and improve fruit production. The tree responds well to organic fertilizers such as compost and well-decomposed manure, which should be applied during the rainy season. Inorganic fertilizers can also be used, but they should be applied in moderation, as excessive use can damage the tree's roots.
Pruning
Pruning is essential in the cultivation of African marula trees, and it should be done annually during the dry season to promote branching and improve fruit production. The pruning process involves the removal of dead and diseased wood, water sprouts, and crossing branches. It is also advisable to thin out the canopy slightly to improve light penetration and air circulation, which reduces the risk of fungal infections.
Propagation Methods for Sclerocarya birrea (A.Rich.) Hochst. subsp. multifoliolata (Engl.) Kokwaro
Sclerocarya birrea (A.Rich.) Hochst. subsp. multifoliolata (Engl.) Kokwaro, also known as the African marula tree, can be propagated through various methods. These include seed propagation, vegetative propagation, and grafting.
Seed Propagation
The easiest and most common way to propagate Sclerocarya birrea is through seeds. The seeds can be collected from ripe fruits, which usually mature during the summer months. The collected seeds should be cleaned, dried, and then sown in trays filled with well-drained soil mix. The trays should be covered with transparent plastic to create a humid environment and promote germination. Germination usually takes about 2-4 weeks, and the seedlings can be transplanted into individual pots once they have developed their first true leaves.
Vegetative Propagation
Another propagation method for Sclerocarya birrea is vegetative propagation, which involves taking cuttings from a mature tree. The best time to take cuttings is during the early spring, just before the onset of new growth. The cuttings should be approximately 15-20cm long and should be taken from the previous year's growth. The leaves on the lower half of the cutting should be removed, and the cutting should be dipped in rooting hormone before planting. The cutting can then be inserted into a well-drained rooting medium and placed in a humid location until roots have formed.
Grafting
Grafting is another effective method of propagating Sclerocarya birrea. This method is commonly used to propagate cultivars that have desirable traits. Grafting involves attaching a scion (a young shoot or bud) from the cultivar tree onto a rootstock of a related species or from a seedling. The preferred technique for grafting is the side graft or cleft graft, where a portion of the stock tree's trunk is cut and split. The scion is then inserted into the cleft and secured in place.
Disease Management
Sclerocarya birrea (A.Rich.) Hochst. subsp. multifoliolata (Engl.) Kokwaro, commonly known as the Marula tree, is generally resistant to many diseases. However, some fungal diseases can affect the tree, such as anthracnose which causes leaf spotting and defoliation. This disease can be managed by pruning the affected parts and destroying them. Regular spraying of fungicide can also help to prevent the disease from spreading to other parts of the tree.
Another fungal disease that can affect Marula trees is powdery mildew. This disease can be treated by the use of fungicides and pruning of infected parts of the tree. Cultural practices such as proper spacing and good air circulation can also help prevent the occurrence of this disease.
Pest Management
The Marula tree is also susceptible to attack by some pests. One of the common pests that attack the tree is the Marula fruit fly. The pest affects the fruit, causing rotting and premature dropping. To manage this pest, it is advisable to pick the fruits early before the fly infests them. Farmers can also use pheromone traps to control the pest population.
Another pest that can attack Marula trees is the stem borer. This pest bores into the stem, causing stunted growth, wilting, and yellowing of the leaves. Pruning and removal of infested branches can help manage the pest. Additionally, the use of insecticides can help control the pest population.
It is important to note that the use of pesticides should be done in a responsible and sustainable manner to avoid further damage to the environment and non-target organisms. Regular monitoring of the trees and prompt action against any pests or diseases can go a long way in ensuring healthy and productive Marula trees.
