Overview of Dichrostachys cinerea (L.) Wight & Arn. subsp. nyassana (Taub.) Brenan
Dichrostachys cinerea (L.) Wight & Arn. subsp. nyassana (Taub.) Brenan, also known as West African sicklebush, is a deciduous shrub or small tree that belongs to the family Fabaceae. It is native to Africa and is predominantly found in countries such as Tanzania, Malawi, Mozambique, and Zimbabwe.
General Appearance and Characteristics
The West African sicklebush can grow up to 6 meters in height, and its stem is often thorny. The bark of the tree is grayish-brown and textured with wavy lines. The leaves of the tree are compound and feathery, with each leaf having 4-10 pairs of small leaflets. The flowers of the tree are pale yellow to cream-colored and grow in cylindrical spikes that are about 5-8 cm long. The tree produces leguminous pods that are narrow and about 10-20 cm long.
Common Names
The West African sicklebush is commonly known by many different names across Africa. In Zimbabwe, it is called Mutukutu while in Tanzania, it is known as Mkindo. In Malawi, it is called Chiwapa while in Mozambique, it is referred to as sereia.
Uses
The West African sicklebush is a versatile plant that has several uses. Its pods are a good source of protein and are edible once cooked. In some parts of Africa, the tree is also used as a traditional medicine to treat various ailments such as fever, diarrhea, and constipation. The wood from the tree is used for fuel and timber, while the thorny stems are used as a barrier against livestock. The West African sicklebush is also a popular ornamental tree and is commonly planted in gardens and along roadsides.
Light Conditions
Dichrostachys cinerea (L.) Wight & Arn. subsp. nyassana (Taub.) Brenan prefers full sun to partial shade. It requires at least six hours of direct sunlight daily to grow well. Inadequate sunlight may cause the plant to grow too tall and have a weak stem.
Temperature Conditions
The plant thrives in high temperatures between 20°C to 35°C, and it can grow in colder or hotter temperatures but not for extended periods. In areas with cold temperatures, the plant may lose its leaves, but it regains them once the temperature warms up.
Soil Requirements
The plant can grow in various soil types, ranging from sandy and loamy soils to highly acidic soils. For optimal growth, the soil should be well-draining and moderately rich in nutrients. Adding organic matter to the soil improves water retention, soil quality, and provides nutrients. The ideal pH level ranges from 5.5 to 7.5.
Cultivation Methods
Dichrostachys cinerea (L.) Wight & Arn. subsp. nyassana (Taub.) Brenan, commonly known as the "sickle bush," is a drought-tolerant plant species that grows mainly in arid and semi-arid regions. It prefers warm and dry climates and can withstand temperatures ranging from 9°C to 40°C. The plant can be grown from seeds or propagation by cuttings.
For seed propagation, soak the seeds in warm water overnight before planting in well-drained soil in a sunny location. Cover the seeds with a light layer of soil and keep the soil moist until the seedlings emerge.
Propagation by cuttings involves taking 10–15 cm long cuttings from mature plants, dipping them in rooting hormone, and planting them in pots filled with well-draining soil. The pots should be covered with a clear plastic bag to maintain humidity and kept in a warm, bright location until the cuttings root.
Watering Needs
Dichrostachys cinerea (L.) Wight & Arn. subsp. nyassana (Taub.) Brenan does not require much water and can survive on minimal rainfall. The plant's root system is relatively deep and can access moisture from deeper soil layers. However, for optimal growth, it is recommended to water the plant once a week during the growing season and reduce watering during the winter or dormancy period.
When watering, avoid waterlogging the soil and ensure that the water penetrates deeply into the soil to encourage the roots to grow deep. Overwatering can lead to root rot, which can damage or kill the plant.
Fertilization
Dichrostachys cinerea (L.) Wight & Arn. subsp. nyassana (Taub.) Brenan is a nitrogen-fixing plant species that can produce its nitrogen. Therefore, it does not require much fertilizer. However, to promote optimal growth, you can apply a balanced, slow-release fertilizer during the growing season.
Apply fertilizer sparingly and follow the manufacturer's instructions. Over-fertilization can lead to excessive leaf growth, which can increase the plant's susceptibility to pests and diseases.
Pruning
Dichrostachys cinerea (L.) Wight & Arn. subsp. nyassana (Taub.) Brenan grows into a small tree with a spreading canopy. Therefore, pruning is essential to maintain its shape and promote healthy growth.
The best time to prune is during the dormant period in winter. You can remove dead, damaged, or diseased branches with pruning shears. Additionally, you can prune to prevent overcrowding and promote air circulation within the tree's canopy.
When pruning, ensure that you make clean cuts and avoid leaving stubs, which can attract pests and diseases. Disinfecting your pruning tools with rubbing alcohol before and after use can also prevent the spread of infections between plants.
Propagation of Dichrostachys cinerea subsp. nyassana
Dichrostachys cinerea subsp. nyassana, commonly known as the Nyassa two-stamen bush, is a shrub or small tree found in the savanna and woodland regions of East and Southern Africa. The plant is valued for its medicinal properties and as a source of wood for fuel, charcoal, and building construction. Propagation of the plant can be done through several methods, including seed propagation and vegetative propagation.
Seed propagation
Seed propagation is the most common method of propagating Dichrostachys cinerea subsp. nyassana. The seeds are collected from mature fruits that have fallen to the ground. It is important to collect the seeds as soon as they fall to the ground to ensure high viability. The seeds should be cleaned of any debris and dried in the shade for a few days before sowing.
The seeds can be sown directly in the field or in polybags filled with a well-draining soil mixture. The soil mixture should be moistened before sowing. The seeds should be sown at a depth of approximately 1 cm and covered with a thin layer of soil. Germination can take anywhere from 1 to 3 weeks.
Vegetative propagation
Vegetative propagation of Dichrostachys cinerea subsp. nyassana can be done through stem cuttings or layering. Stem cuttings are taken from the current season's growth and should have at least 3 to 4 nodes. The lower leaves should be removed, and the cuttings should be treated with a rooting hormone before planting. The cuttings can be planted in a well-draining soil mixture, and kept in shade until roots have formed.
Layering involves bending a low-growing branch to the ground and burying a section of it under the soil. The buried section should be wounded and treated with a rooting hormone to promote root growth. The plant can be left in place until roots have formed, after which it can be separated from the parent plant and transplanted.
Both seed propagation and vegetative propagation can be successful with proper care and attention to detail, resulting in healthy and thriving Dichrostachys cinerea subsp. nyassana plants.
Disease Management
Dichrostachys cinerea subsp. nyassana could face several disease problems that can reduce the quality and quantity of its yield. Here are some of the common disease problems known to affect it:
- Anthracnose: This fungal disease causes the leaves of the plant to turn yellow or brown and eventually fall off. It can also cause the plant to wilt and die off at a young age. Regular pruning and removal of affected plant parts are essential in managing the disease. Fungicides can also be used to control it.
- Root Rot: This disease is caused by a fungus that attacks the plant's roots, causing them to rot. It can lead to wilting, stunted growth, and ultimately the death of the plant. To manage root rot, ensure proper drainage and avoid overwatering the plant. Fungicides may also be applied to infected plants.
- Powdery Mildew: This fungal disease manifests as a white powdery coating on the plant's leaves, making them appear grayish. It can cause leaf deformation, yellowing, and premature falling. Powdery mildew can be managed by maintaining good air circulation around the plant, avoiding overhead watering, and applying fungicides.
Pest Management
In addition to diseases, Dichrostachys cinerea subsp. nyassana may also fall prey to pests, and some of the common ones include:
- Whiteflies: These insects feed on the sap of the plant, causing yellowing and deformation of the leaves. They also excrete honeydew that attracts other insects and promotes the growth of fungal diseases. Whiteflies can be managed using insecticides and physical barriers such as sticky traps.
- Aphids: These pests suck sap from the plant's leaves and stems, causing curling and yellowing of leaves and stunted growth. Regularly removing affected plant parts and applying insecticides can help manage aphids.
- Caterpillars: These insects feed on the plant's leaves and buds, causing extensive damage that may result in reduced yields. Handpicking and application of natural predators such as parasitic wasps can help manage caterpillars.
