Overview
Grewia columnaris Hochst. is a small tree or shrub belonging to the family Malvaceae. It is a native plant of East and Central Africa, particularly in Tanzania, Kenya, and Ethiopia. The plant is also known by its common names, such as the Waterberry and Mukwaju.
Description
The leaves of Grewia columnaris Hochst. are oval-shaped, with a pointed tip, and have a length of about 2-6 cm. They are arranged on the branches in an alternate pattern. The bark of the tree is smooth and greyish-brown in colour. The flowers of the plant are small, creamy-white, and appear in clusters at the axils of the leaves. The fruit of Grewia columnaris Hochst. is a plum-sized berry that is edible and has a sweet taste.
Uses
Grewia columnaris Hochst. has various uses in traditional medicine. The roots and bark of the plant are used to treat diarrhoea and dysentery. The leaves of the tree can be crushed and used as a poultice for treating wounds. The fruit of the plant is edible and is often consumed raw or used to make jams or jellies. The wood of the tree is also used for construction purposes, such as making furniture or fences.
Aside from its medicinal and practical uses, Grewia columnaris Hochst. is also used for ornamental purposes due to its attractive appearance. The tree's showy flowers and bright-coloured fruit make it an excellent addition to gardens and landscaping projects.
Light Requirements
Grewia columnaris Hochst. is a sun-loving plant and thrives well in full sun or partial shade. The plant requires a minimum of 6-8 hours of bright sunlight to stimulate its growth and promote flowering.
Soil Requirements
The plant prefers well-drained and fertile soils. However, it can tolerate a wide variety of soil types, such as sandy, loamy, and clay soils. Grewia columnaris Hochst. prefers a slightly acidic to neutral soil pH ranging from 5.5 to 7.5. The plant is relatively drought-tolerant, but it requires regular watering during prolonged dry spells to maintain its growth and health.
Temperature Requirements
Grewia columnaris Hochst. is a native tropical plant and prefers warm to hot temperatures to grow. The plant thrives well in temperatures ranging from 20°C to 40°C. However, it can tolerate temperatures as low as 2°C during the dormant season. The plant can grow well in areas with an average annual temperature of 25°C-30°C.
Cultivation of Grewia columnaris Hochst.
Grewia columnaris Hochst. is a shrub originating from East Africa. It can be grown as a hedge or a single plant in a pot or garden bed. The shrub grows well in full sun or partial shade.
The plant prefers fertile soil that is well-draining. It should be planted in soil that is rich in organic matter and slightly acidic. Before planting, it is essential to prepare the soil by digging it over and adding compost to improve its fertility and drainage.
Watering needs of Grewia columnaris Hochst.
Grewia columnaris Hochst. requires moderate watering, especially during the summer months. The shrub does not like to be in soil that is too wet. Overwatering can cause root rot, which can be lethal for the plant. The best time to water the shrub is in the early morning or late afternoon. During these times, the temperature is cooler, and evaporation is minimized.
Fertilization of Grewia columnaris Hochst.
Grewia columnaris Hochst. requires occasional fertilization to thrive. A balanced fertilizer that contains equal proportions of nitrogen, phosphorus, and potassium can be applied in the early spring. The fertilizer should be applied according to the manufacturer's instructions. Over-fertilization can lead to excessive leaf growth and reduced flowering.
Pruning of Grewia columnaris Hochst.
Grewia columnaris Hochst. requires occasional pruning to maintain its shape and encourage new growth. The shrub should be pruned after flowering in the late spring or early fall. The pruning should involve the removal of old or diseased branches. The shrub should be pruned to maintain a neat and compact shape.
Propagation of Grewia columnaris Hochst.
Grewia columnaris Hochst. is propagated through seeds and cuttings. The species is easy to propagate, and the following are some of the propagation methods used:
Seed Propagation
Seeds are collected from mature fruits and cleaned before sowing. Pre-treatment of the seeds is essential to break dormancy and enhance germination. This can be achieved by soaking the seeds in warm water for 24 hours, or stratifying them in moist sand at 10°C for about three months. Seeds can be sown directly in a nursery bed or in pots filled with a growing medium such as peat moss and sand. The optimum temperature for germination is 25-30°C, and the seeds usually take 2-3 weeks to germinate. The seedlings are transplanted to individual pots or directly to the field when they are about 10-15cm tall.
Cutting Propagation
Cuttings are obtained from the current season's growth. Semi-hardwood cuttings with a length of 15-20cm and a diameter of 0.5-1.0cm are suitable for propagation. The cuttings are treated with a rooting hormone such as IBA and planted in a rooting medium such as sand or peat moss. The cuttings are kept in a moist and humid environment under shade until they root, which may take 4-8 weeks. The rooted cuttings are transplanted to individual pots or directly to the field.
Disease and Pest Management for Grewia Columnaris Hochst.
Grewia Columnaris Hochst., also known as Lavender Star Flower or African Starbush, is a hardy plant that can grow up to six meters tall. However, it is susceptible to a range of pests and diseases that can cause damage to the plant. Here are some common diseases and pests that can affect Grewia Columnaris Hochst. and ways to manage them:
Diseases
Fungal Diseases: Grewia Columnaris Hochst. can be affected by a range of fungal diseases such as root rot, leaf spot, and anthracnose. These diseases can cause the plant to yellow and wilt, and can even kill the plant. To manage fungal diseases, practice good hygiene by removing diseased leaves and branches from the plant. Use a fungicide to control the spread of the disease. Avoid overwatering the plant and make sure the soil is well-drained.
Viral Diseases: Viral diseases can cause a range of symptoms in Grewia Columnaris Hochst. such as yellowing, mottling, and stunting. Unfortunately, there is no cure for viral diseases, so it is important to remove and destroy infected plants to prevent the spread of the virus. Make sure to use sterile pruning tools to avoid spreading the virus to healthy plants.
Pests
Mites: Spider mites are a common pest that can damage Grewia Columnaris Hochst. They suck the sap of the plant, causing it to yellow and dry out. To manage mites, spray the plant with water to dislodge them. Apply insecticidal soap or a miticide to kill the remaining mites.
Caterpillars: Caterpillars can cause damage to the leaves of Grewia Columnaris Hochst. To manage caterpillars, remove them by hand from the plant and dispose of them. Use a biological insecticide that contains Bacillus thuringiensis to control their population.
Scale Insects: Scale insects can cause the leaves of Grewia Columnaris Hochst. to turn yellow and fall off. They also produce a sticky substance called honeydew that attracts ants and promotes the growth of sooty mold. To manage scale insects, apply insecticidal soap or horticultural oil to the plant. Prune heavily infested branches and dispose of them properly.
By following these disease and pest management tips, you can promote the health of your Grewia Columnaris Hochst. plant and ensure that it grows strong and beautiful.
