Overview
Grewia tenax (Forssk.) Fiori var. erythraea (Schweinf.) Chiov. is a medium-sized shrub that belongs to the Malvaceae plant family. This plant species is also known by several common names, including Red-stem Grewia, Grewo, and Mtomondo. It is native to the African continent and can be found growing naturally in various regions across Africa such as Ethiopia, Tanzania, South Sudan, and Uganda.
Appearance
Grewia tenax is a multi-stemmed shrub that can grow up to 3 meters tall. It has a round to oval-shaped crown that is densely covered with leaves. The leaves are alternate, broad, and ovate in shape, measuring about 4-7 cm long. The bark of the plant is smooth and greyish-white, while the branches are thin and red in color.The flowers of the Grewia tenax are small, greenish-yellow, and arranged in clusters. The fruit is a small, round, and fleshy drupe that turns purple or black when ripe.
Uses
The Grewia tenax plant has many uses. For instance, the bark and leaves of the plant are used in traditional African medicine to cure various ailments such as diarrhea, dysentery, and stomach aches. Additionally, the fruit is edible and is consumed raw or processed into jams, jellies or added to porridges. The plant is also a source of traditional fiber used in basket weaving. Furthermore, the plant is used in agroforestry as windbreakers, soil stabilizers, and nitrogen fixers in soil rejuvenation and conservation practices.
Cultivation
Grewia tenax can grow in a wide range of soils, including sandy, clay, and loamy soils, and soil PH from neutral to slightly acidic. The plant prefers full to partial sun exposure and is relatively drought-tolerant. Grewia tenax can be propagated through seeds or stem cuttings. It can also be propagated through air-layering. As a shrub, it requires regular pruning to promote bushy growth and remove dead or diseased wood.
Light Requirements
Grewia tenax var. erythraea requires full sun exposure for optimal growth. The plant can tolerate partial shade, but it may have stunted growth and reduced fruit production in such conditions.
Temperature Requirements
The plant thrives in warm and humid climatic conditions. Grewia tenax is naturally adapted to tropical and subtropical environments. It requires a temperature range of 20°C to 35°C for optimal growth.
If exposed to temperatures below 10°C, the plant may suffer from frost damage, which can result in leaf discoloration, wilting, and reduced fruit production.
Soil Requirements
Grewia tenax var. erythraea prefers well-draining soils with a pH range of 6.0 to 8.5. The plant can thrive in a variety of soil types, including sandy, loamy, and clay soil. However, it prefers a deep and fertile soil that is rich in organic matter.
The plant is adapted to dry conditions and can tolerate moderate drought. Excessive moisture in the soil can lead to root rot, which can cause stunted growth and reduced fruit production.
Cultivation Methods
Grewia tenax (Forssk.) Fiori var. erythraea (Schweinf.) Chiov. is a drought-resistant shrub that is native to the Horn of Africa. This plant thrives in hot and dry conditions and can be grown in a wide range of soils.
The first step in the cultivation process is to select a planting site with well-draining soil that receives plenty of sunlight. The soil should be slightly acidic with a pH of 5.5-7.0 and a fertility level of moderate to high.
The best planting time for Grewia tenax is during the rainy season when the soil is moist and the temperature is cool. The plants should be spaced at least 3 meters apart to allow for adequate root growth.
Watering Needs
Watering is essential for newly planted Grewia tenax until it becomes established. After that, the plant is drought-resistant and can survive without being watered frequently.
The frequency and the amount of watering depend on the climate, soil type, and plant age. During the hot and dry season, it is recommended to water the plant every two weeks. However, in areas with regular rainfall, the plant may not require regular watering.
It is important to monitor the soil moisture level and water the plants accordingly. Overwatering or underwatering can impact the plant's growth and health.
Fertilization
Grewia tenax requires moderate fertilization to increase its growth rate and produce more fruits. The plant requires a balanced NPK fertilizer with a ratio of 10-10-10 or 15-15-15.
Fertilizer should be applied during the rainy season when the plant begins to grow actively. The amount of fertilizer depends on the age and size of the plant. For young plants, apply 25-50 grams of NPK fertilizer, while for mature plants, apply up to 200 grams.
However, excessive fertilizer application can lead to foliage growth at the expense of fruit production. It is, therefore, essential to use fertilizers based on soil test results and the plant's nutritional requirement.
Pruning
Regular pruning of Grewia tenax is necessary to remove diseased, broken, or damaged branches. Pruning also helps to keep the plant in a compact shape and increase fruit production.
The best period to prune is after harvesting the fruits during the dry season. This period is ideal as the plant is dormant, and the pruning wounds will heal quickly. Avoid pruning during the rainy season as it can encourage the growth of diseases.
When pruning, ensure the cuts are clean and smooth, and the pruning equipment is sterilized to avoid infecting the plant with diseases. Only remove a maximum of one-third of the tree's canopy to avoid excessive stress on the plant.
Propagation of Grewia tenax var. erythraea
Grewia tenax var. erythraea, also known as Red False Grewia or Djidjibin in Somalia, is a hardy shrub or small tree that is widely distributed throughout tropical Africa. It is highly valued for its edible fruit and medicinal properties. Propagation of G. tenax var. erythraea can be achieved through various methods which include:
Seed Propagation
Seed propagation is the most common and easiest method of propagating G. tenax var. erythraea. As the seeds have a hard coat, they require mechanical or chemical scarification to aid germination. After scarification, the seeds should be soaked in water for a few hours before planting. Plant the seeds in a well-draining potting mix. The seedlings should emerge in about 2-3 weeks after sowing. Once the seedlings have reached appropriate size, they can be transplanted into larger containers or directly into the ground.
Cuttings Propagation
Cuttings propagation is another method that is often used for G. tenax var. erythraea. Softwood cuttings are usually used for this method. Choose healthy, young, and green stem sections of about 10 to 15 cm. Remove all leaves except for a few at the top. Dip the cut end of the stem in rooting hormone powder and plant in well-draining potting mix. Ensure that the potting mix is moist but not waterlogged. Cover the cuttings with a plastic bag to maintain high humidity levels. The cuttings should develop roots in about 3 weeks and can then be transplanted to larger containers or directly into the ground.
Air Layering Propagation
Air layering can also be used to propagate G. tenax var. erythraea. This method involves wrapping a section of the stem with moist sphagnum moss and then covering it with plastic wrap. Once roots have developed, the propagated section can be separated from the parent plant and transplanted into a pot or directly into the ground.
Conclusion
G. tenax var. erythraea is an important plant, and its propagation is critical for its conservation and exploitation. Different methods of propagation are available, and the method to be chosen should be determined by the availability of materials and expertise.
Disease and Pest Management for Grewia Tenax var. Erythraea
Grewia tenax var. erythraea is a hardy shrub that is tolerant to many pests and diseases. However, it may still suffer from some common problems. Here are the most common diseases and pests that may affect this plant and ways to manage them.
Diseases
Anthracnose: This fungal disease causes leaf blight, twig dieback, and cankers on the stem. You can manage anthracnose by removing infected plant parts and disposing of them properly to prevent the spread of the disease. Apply a fungicide to protect the plant from further infection.
Leaf Spot: Another fungal disease that causes small spots on the leaves. The spots will enlarge and turn brown, causing the leaves to drop. To manage this disease, remove infected plant parts and apply a fungicide.
Pests
Aphids: Aphids are tiny insects that suck the sap from the plant, causing leaves to curl and turn yellow. To manage them, spray the plant with an insecticidal soap. You can also introduce natural predators such as ladybugs and lacewings to control aphid populations.
Mites: Spider mites are a common pest that can cause yellowing leaves and webbing on the plant. To manage them, spray the plants with an acaricide or insecticidal soap. You can also introduce natural predators such as predatory mites to control mite populations.
Caterpillars: Caterpillars can cause defoliation and damage to the plant. To manage them, manually remove caterpillars and apply a biological pesticide. You can also introduce natural predators such as birds and wasps to control caterpillar populations.
Overall, prevention is key in managing diseases and pests in your Grewia tenax var. erythraea. Keeping the plant healthy and well-watered will help it resist infections and pest attacks. Regularly inspecting the plant for signs of problems and promptly managing any issues that arise will help ensure the plant's long-term health.
