Description
Acacia abyssinica Hochst. ex Benth. subsp. calophylla Brenan is a deciduous tree that belongs to the legume family (Fabaceae) and is native to eastern Africa, particularly Ethiopia and Tanzania. This plant is a subspecies of Acacia abyssinica, commonly known as the Arabian gum or gum arabic tree.
General Appearance
The Acacia abyssinica Hochst. ex Benth. subsp. calophylla Brenan can grow up to a height of 12-20 meters and has a rounded and spreading crown. It has a straight, cylindrical trunk that is covered with grayish-brown bark with horizontal cracks. The leaves of this plant are bipinnate and are arranged alternately along the stem with each pinna containing 10-20 leaflets. The flowers of this plant are small and yellow, forming clusters that are about 1 cm in diameter. The fruits are long, slender pods that are brownish-black in color.
Common Names
The Acacia abyssinica Hochst. ex Benth. subsp. calophylla Brenan is known by several common names such as African myrrh, musaie, Busaka, and Himalayan silver fir. In Ethiopia, it is locally known as "susu" and in Tanzania, it is called "kikarazu."
Uses
The Acacia abyssinica Hochst. ex Benth. subsp. calophylla Brenan has several traditional medicinal uses in African countries. The leaves, bark, and gum of this plant are used to treat various ailments such as coughs, sore throats, wounds, and respiratory problems. The gum from this plant is also used in the food industry as a stabilizer and thickening agent. The wood of the African myrrh tree is used in woodworking, and its bark is used to make ropes and baskets. In addition, this tree is used in environmental and forestry restoration programs due to its ability to fix nitrogen in the soil and its adaptability to arid conditions.
Light requirements
The Acacia abyssinica subsp. calophylla Brenan prefers full sun exposure and can grow in areas with high light intensity. The species can tolerate shade for a short period, but it may affect its growth and flowering ability.
Temperature requirements
The plant can withstand a wide range of temperatures, but it thrives well in an average temperature of 20-25°C. It can tolerate temperatures as low as 12°C and as high as 40°C. However, it can suffer from frost damage when temperatures drop below 0°C.
Soil requirements
Acacia abyssinica subsp. calophylla Brenan prefers well-drained soils with a pH range of 5.5-8.0. The species can also thrive in sandy, rocky, and clay soils. It prefers soils that are rich in organic matter, nitrogen, and phosphorus. However, it can tolerate soils with low fertility and moisture stress. The plant can grow in areas with an annual rainfall range of 400-800 mm but can survive in areas with up to 1200 mm of annual rainfall.
Cultivation Methods
Acacia abyssinica Hochst. ex Benth. subsp. calophylla Brenan, also known as the red-barked acacia, is a drought-tolerant plant that grows well in subtropical and tropical climates. It can be propagated from cuttings, seeds, or by root suckers. Cuttings taken in the winter will root in 6-8 weeks while seeds should be planted immediately after harvesting. The plant prefers full sun and well-drained soil. It has a strong taproot and should be planted in a deep hole.
Watering Needs
While the red-barked acacia is drought-tolerant, it benefits from regular watering during its growing season, which is from mid-spring to fall. It's important not to over water, which can cause root rot. The plant should be watered deeply once a week, rather than frequent shallow watering. In winter, it requires little to no water.
Fertilization
In its natural habitat, the red-barked acacia grows in poor soils, so it doesn't require a lot of fertilization. You can add a slow-release nitrogen fertilizer to the soil every spring to help the plant grow, but it's not necessary. Over-fertilization can cause the plant to grow too quickly and become weak.
Pruning
The red-barked acacia should be pruned in the winter before the growing season starts. Prune any damaged or diseased branches, and cut back any vigorous new growth. This will promote branching and a more full-bodied shape. It's important not to prune too much, as the plant has a unique natural form that shouldn't be overly manipulated.
Propagation of Acacia abyssinica Hochst. ex Benth. subsp. calophylla Brenan
Acacia abyssinica Hochst. ex Benth. subsp. calophylla Brenan can be propagated through both sexual and asexual methods.
Sexual propagation
Seeds are the most common and easiest way to propagate A. abyssinica. The seeds need to be collected from the tree when they are mature and dry. They should then be cleaned and stored in a cool, dry place until planting.
Before planting, the seeds should be soaked in hot water for 24 hours to break their hard seed coat. After soaking, the seeds can be planted in seedling trays or pots containing well-draining soil mix. The containers should be kept in a warm and well-lit area with consistent moisture until germination.
Asexual propagation
A. abyssinica can be propagated asexually through cuttings, layering, and grafting.
Cuttings are taken from young branches and should be around 10-20 cm in length. The leaves on the lower half of the cutting should be removed, and the cutting should be planted firmly in a well-draining soil mix. The container should be kept in a warm and well-lit area with consistent moisture until roots develop.
Layering involves bending a young branch to the ground and covering it with soil until it forms roots. Once roots have formed, the branch can be cut from the parent plant and transplanted.
Grafting involves taking a healthy branch from a desired variety and attaching it to a rootstock of A. abyssinica. The two are then bound together until they fuse and start to grow as one plant.
Disease and Pest Management for Acacia abyssinica subsp. calophylla
Acacia abyssinica subsp. calophylla Brenan is a resilient plant with minimal disease and pest infestation. However, certain environmental factors can make it susceptible to diseases and pests.
Common Diseases
Root rot is a common disease that affects Acacia abyssinica subsp. calophylla Brenan. It is caused by excessive moisture in the soil, leading to leaf yellowing, wilting, and eventual plant death. To manage this, reduce watering and improve soil drainage. Fungicides can also be applied to the soil to prevent further spread of the disease.
Leaf spots are another common disease that can affect the plant. It manifests as brown or black spots on the leaves, leading to leaf drop and stunted growth. Proper plant spacing and adequate air circulation can help prevent the spread of the disease. Fungicides can also be used to control the disease in severe cases.
Common Pests
The most common pests that affect Acacia abyssinica subsp. calophylla Brenan are caterpillars, aphids, and spider mites. Caterpillars feed on the leaves, causing defoliation while aphids and spider mites suck sap from the leaves, leading to stunted growth and yellowing.
To manage these pests, regular inspections should be done to monitor their presence. Handpicking caterpillars and spraying insecticides can control their population. Natural predators like ladybugs and lacewings can also be introduced to control aphids and spider mites.
Conclusion
With proper care and regular inspections, Acacia abyssinica subsp. calophylla Brenan can be kept healthy and free from diseases and pests.
