Overview
Lannea rubra (Hiern) Engl. var. serrata Van der Veken, also known as West African lannea or koka tree, is a deciduous plant species belonging to the family Anacardiaceae. It is native to tropical and subtropical Africa, from Senegal east to Sudan and south to Zimbabwe and Angola.
General Appearance
The koka tree is a medium to large-sized plant that can grow up to 25 meters tall. It has a straight trunk with gray-brown bark that is rough and furrowed. The leaves are alternate, pinnately compound, and serrated, with 6-10 pairs of leaflets that are 6-20 cm long and 2-6 cm wide. The young leaves are reddish or bronze in color, which later turn green as they mature. The flowers are small, inconspicuous, and yellowish-green in color, arranged in axillary panicles that are 7-15 cm long. The fruits are globose drupes that are 1-2 cm in diameter and red when ripe, containing one hard seed.
Common Names
The plant has several common names depending on the region, such as koka tree, West African lannea, monkey guava, African grapefruit, and more. In some parts of Africa, the tree is also known for its fruit, called "wisa" in Ghana and "hirfa" in Sudan, where it is eaten fresh, dried, or used in the preparation of local drinks and food.
Uses
The koka tree has a wide range of uses in traditional medicine, where its various plant parts are used to treat various ailments, such as diarrhea, dysentery, fever, cough, and inflammation. The bark is used as a toothbrush and as a source of tannins for dyeing and tanning leather. The wood is hard and durable, making it suitable for construction, furniture, and charcoal production. The fruits are also edible and have a slightly acidic and sweet taste, making them an important source of food and income for local communities.
Light Requirements
Lannea rubra var. serrata prefers full sun to partial shade for optimal growth and development. It can tolerate some shade but the plant may become leggy and produce fewer flowers if grown in very shady conditions. When grown indoors, the plant should be placed near a window that receives bright, indirect sunlight.
Temperature Requirements
This plant is native to tropical and subtropical regions of Africa and thus, it thrives in warm temperatures. The ideal temperature range for growth is between 20-30°C (68-86°F). It can tolerate temperatures as low as 10°C (50°F) for short periods, but temperatures below this can cause damage to the plant. In colder regions, it should be grown indoors or in a greenhouse.
Soil Requirements
Lannea rubra var. serrata is not particular about soil type as long as it is well-draining and has a good amount of organic matter. It can grow in sandy, loamy, or clay soils as long as they are not waterlogged. The pH of the soil should be between 6.0-7.5 for optimal growth. When planting, it is important to ensure the soil is thoroughly moistened and to water regularly to prevent the soil from drying out.
Cultivation Methods
Lannea rubra (Hiern) Engl. var. serrata Van der Veken is a native shrub grown for its ornamental and medicinal values. It is cultivated in tropical and subtropical regions, primarily for aesthetic value. The plant prefers well-drained soils, with a pH ranging from 5.5-7.5 for optimal growth. The shrub can be propagated by stem cuttings, air layering, or seedlings.
Watering Needs
Lannea rubra has a moderate water requirement. Watering should be done regularly during its growing season, particularly when the soil is dry to the touch. However, over-watering should be avoided as it may cause root rot and damage to the plant. The plant is drought-tolerant, and so it can survive short periods of water scarcity.
Fertilization
The plant requires a balanced fertilizer, preferably a complete NPK mix, every two to three months during its growing period. Fertilization should be done after watering to reduce the risk of fertilizer burn on the roots. The shrub responds well to organic manure, which should be applied at the beginning of the growing season to improve soil quality and promote healthy growth.
Pruning
The shrub requires regular pruning to maintain its shape and promote optimal growth. Pruning should be done after the flowering season to prevent damage to its buds. Dead or damaged branches should be removed immediately to avoid the spread of diseases. The plant can withstand hard pruning, and so it can be cut back to ground level to rejuvenate its growth.
Propagation of Lannea rubra var. serrata
Lannea rubra var. serrata Van der Veken, commonly known as the African apple, is a deciduous tree species that belongs to the family Anacardiaceae. It is native to different parts of Africa and is known for its edible fruit, medicinal properties, and ornamental value. The plant can be propagated through various methods, including:
Seed Propagation
Seed propagation is the most common method used to propagate the African apple. The seeds are collected from mature fruits, cleaned, and allowed to dry in the shade. They are then sown in a well-draining seedbed filled with a mixture of sand and compost or topsoil. The seedbed should be kept moist but not waterlogged, and the seedlings should start to emerge within two to three weeks.
The seedlings are grown in the seedbed until they reach a height of about 10cm, after which they can be transplanted into individual pots or directly into the ground. During transplantation, care should be taken to avoid damaging the roots, and the plant should be watered immediately after transplanting.
Cutting Propagation
Cutting propagation is another method used to propagate the African apple. It involves taking stem cuttings from mature trees and rooting them to produce new plants. The best time to take cuttings is during the rainy season when the plant is actively growing.
The cuttings should be about 15-20cm long and should be taken from the middle or upper part of the tree. The leaves on the lower part of the cutting should be removed, and the cutting should be treated with a rooting hormone. The cutting is then planted in a well-draining rooting medium, such as sand or vermiculite, and placed in a warm, humid environment. The cuttings should start to root within four to six weeks, and they can be transplanted into individual pots or directly into the ground.
Air Layering
Air layering is a propagation method used to reproduce the African apple that involves making a cut in the stem and inducing roots to form at the cut area. It is a recommended method for propagating mature plants with desirable traits.
The stem to be air layered should be selected carefully and treated with a rooting hormone. A section of the bark, about 2-5cm long, is then removed, and the exposed area is wrapped with a moist, rooting medium, such as sphagnum moss or peat moss. The area is then wrapped with plastic to retain moisture and kept in a warm place.
Roots should begin to form in 2-3 months. When the development of roots is sufficient to support the growth of the plant, the rooted section is separated from the original plant and transplanted into soil or a pot.
Disease Management
The Lannea rubra plant is relatively resistant to many diseases. However, it can still be susceptible to various plant illnesses, and some of the common diseases that might affect it include:
- Anthracnose: It is a fungal disease that causes damage to leaves, flowers, and fruits of the plant. The signs of the disease include the appearance of small, dark, and round spots on the leaves that can coalesce to form larger lesions. To manage the disease, ensure to maintain adequate spacing between plants, remove and dispose of infected plant debris, and apply fungicides early in the season.
- Root rot: It is a soil-borne fungal disease that attacks the plant's root system and causes it to rot. The plant becomes stunted, the leaves turn yellow and wilt, and the plant eventually dies. To manage this disease, control the soil's moisture content, improve drainage, and avoid over-watering the plant.
- Leaf spot: It is a fungal disease that affects the leaves of the plant. The symptoms include the appearance of brown to black circular spots on the leaves. The leaves eventually die and fall off, leading to defoliation. To control the disease, remove infected leaves and dispose of them and apply fungicides to the plant.
Pest Management
Various pests might affect the Lannea rubra plant. Some of the common pests include:
- Caterpillars: They are insects that attack the leaves of the plant, causing defoliation. To manage caterpillars, handpick them from the plant, or spray with insecticides.
- Aphids: They are small, soft-bodied insects that suck sap from the plant, causing the leaves to curl and distort. To manage aphids, use insecticidal soap or neem oil.
- Mealybugs: They are white, cotton-like insects that suck sap from the plant. They cause a reduction in plant growth and can transmit diseases. To manage mealybugs, use insecticidal soap or horticultural oil.
Regular inspection of the plant and early detection of pest infestations is necessary to prevent extensive damage. Applying integrated pest management techniques can help manage pests effectively, without causing harm to the plant or the surrounding environment.
