Overview
Acacia caffra (Thunb.) Willd. var. transvaalensis Glover, also known as the Boekenhout tree, is a medium-sized deciduous tree.
Origin and Distribution
The Boekenhout tree is an indigenous plant of Southern Africa, and can be found in parts of South Africa, Zimbabwe, Mozambique, and Swaziland. In South Africa, it grows in the savannah and bushveld regions of the country.
Common Names
The Boekenhout tree has several common names, including the Fever tree, the Blue-leaved Acacia, and the Forest Acacia. These names have been given due to its various properties.
Description
The Boekenhout tree can grow up to a height of 15 meters and has a trunk diameter of about 60 centimeters. It has a smooth, grey bark when young, which becomes rougher and darker as the tree ages. The leaves are light green to blue-green in colour and have a feathery, fern-like appearance. The tree produces a yellow-green flower in the summer months and a long, thin, flattened seedpod in the autumn.
Uses
The Boekenhout tree has various uses. The bark is used to make traditional medicine to help relieve symptoms of fever, colds, and flu. It is also a popular garden tree due to its striking appearance and fast growth rate. Additionally, the high-quality wood of the tree is used in carpentry, furniture-making and as a source of charcoal.
Light Requirements
Acacia caffra var. transvaalensis prefers to grow in full sunlight. It can tolerate partial shade, but excessive shade hinders its growth and development. Therefore, it is best to plant this species in areas that receive at least 6 hours of direct sunlight per day.
Temperature Requirements
This plant species is native to South Africa and can tolerate high temperatures. It prefers warm and humid climates with temperatures ranging from 18°C to 30°C. Acacia caffra var. transvaalensis is also tolerant of frost, withstanding temperatures down to -7°C.
Soil Requirements
Acacia caffra var. transvaalensis grows best in well-draining soils that are rich in organic matter. It can also grow in clay soils, but drainage is crucial. This species prefers slightly acidic to alkaline soils with a pH range of 6.0 to 8.0. It is also drought-tolerant and can withstand prolonged periods of drought once established.
Cultivation Methods
Acacia caffra (Thunb.) Willd. var. transvaalensis Glover, commonly known as the Transvaal thorn, is a hardy plant that can tolerate various soil types, including sandy, loamy, and clay soils. It grows best in well-drained soil with a neutral pH level. The plant requires full sunlight to thrive and forms a dense canopy, making it an excellent choice for hedging and screening. Transvaal thorn can be propagated from seed or cuttings and can be planted in the spring or fall.
Watering Needs
Although Transvaal thorn is a drought-tolerant plant, it still requires regular watering during the first year after planting to establish its root system. Afterward, it requires minimal watering, only during extended periods of dryness. Transvaal thorn is susceptible to root rot, so ensure the soil has excellent drainage to prevent excess water from pooling around the roots.
Fertilization
Transvaal thorn is a nitrogen-fixing plant that can source nitrogen from the air and the soil. Fertilization is only necessary if the soil quality is poor. A balanced fertilizer with equal parts nitrogen, phosphorus, and potassium can be applied during the initial planting or in early spring. However, avoid over-fertilizing, as this may lead to excessive foliage growth, which can attract pests and diseases.
Pruning
Transvaal thorn requires minimal pruning, making it a low maintenance plant. It can tolerate heavy pruning and reshaping, which is typically done during the late winter when the plant is dormant. Pruning is necessary to remove dead, diseased, or damaged branches to maintain the plant's health and appearance. Additionally, pruning can encourage new growth and maintain the desirable density of the plant's canopy.
Propagation methods for Acacia caffra var. transvaalensis
Acacia caffra var. transvaalensis can be propagated through both sexual and asexual methods.
Sexual propagation
The plant produces seeds in pods that are 11-13 cm long. The seeds can be collected from the ripe pods, which turn yellowish-brown and start to open. Scarification, or the process of breaking the hard seed coat, can help improve germination rates. This can be done by soaking the seeds in hot water for up to 24 hours or by nicking the seed coat with a sharp knife.
Once scarified, the seeds can be sown in well-draining soil at a depth of 2-3 cm. The soil should be kept moist but not waterlogged. Germination can take up to three months, and the seedlings should be protected from direct sunlight until they are stronger.
Asexual propagation
Acacia caffra var. transvaalensis can also be propagated asexually. This is often preferred for cultivars that have desirable traits, as it ensures that the new plant is genetically identical to the parent plant.
One common method of asexual propagation is through stem cuttings. Cuttings should be taken in the spring or early summer from the current year's growth. They should be 10-15 cm long and include at least two nodes, or the points from which leaves emerge. The lower leaves should be removed, leaving only one or two at the tip.
The cuttings can be treated with rooting hormone to encourage the growth of roots. They should then be planted in well-draining soil and kept moist, with high humidity. Rooting can take several weeks, and the new plants should be protected from direct sunlight until they are established.
Disease Management
The Acacia caffra (Thunb.) Willd. var. transvaalensis Glover plant is susceptible to some diseases that can harm its growth and health. Below are some common diseases that might affect the plant and suggestions for managing them:
Fungal Leaf Spots
Fungal leaf spots are common diseases that can affect the Acacia caffra (Thunb.) Willd. var. transvaalensis Glover plant. These spots are caused by different types of fungi and can easily spread to other parts of the plant. To manage this disease, it’s essential to keep the foliage dry by watering the plant from the base rather than from overhead. It’s crucial to remove the affected leaves, apply a fungicide and maintain good air circulation to minimize fungal growth.
Root Rot
Root rot is a fungal disease that occurs when the plant's roots are constantly wet. Overwatering or poorly draining soil favors the growth of fungi that can attack the plant's roots, causing rot. To prevent root rot, avoid overwatering the plant and ensure proper soil drainage. Additionally, it could help if you removed any soil around the affected roots, apply a fungicide, and improve the plant's growing conditions to encourage good root growth.
Pest Management
The Acacia caffra (Thunb.) Willd. var. transvaalensis Glover plant is susceptible to pests that can harm its growth and health. Below are some common pests that might attack the plant and suggestions for managing them:
Aphids
Aphids are tiny, pear-shaped insects that can cause damage to the Acacia caffra (Thunb.) Willd. var. transvaalensis Glover plant by sucking the sap from the leaves, causing them to wilt or deform. To manage aphids, you can spray the infected plant with a strong stream of water to remove them. Additionally, applying insecticidal soap or oil can help control the pest.
Thrips
Thrips are small, slender insects that attack the Acacia caffra (Thunb.) Willd. var. transvaalensis Glover plant by piercing the leaves and sucking the sap from them. This can cause the leaves to yellow, curl, and drop. Neem oil application can manage or prevent thrips and other insects by disrupting their feeding habits and slowing down their growth. You could also try introducing natural predators like ladybugs to eat the pests.
