Origin
Derris stuhlmannii (Taub.) Harms is a climbing plant species that is native to tropical Africa, particularly Tanzania, Kenya, and Mozambique.
Common Names
The plant is commonly known as Stuhlmann's derris, red-bean vine, and mbohi.
Uses
Derris stuhlmannii is a versatile plant with various uses. Its roots and stems contain toxic compounds that are used for insecticidal and piscicidal purposes. The local communities in Africa use the plant to harvest different fish species. They crush the roots and stems, mix them with water, and then pour them into the rivers and lakes. This mixture is toxic to fish and causes them to float up, making them easy to catch.
The plant is also traditionally used for medicinal purposes, including the treatment of malaria, fever, and skin diseases. The plant's bark can be useful for treating diarrhea, stomach ache, and other gastrointestinal discomfort.
General Appearance
Derris stuhlmannii is a woody vine that climbs by twisting around other plants or structures. Its leaves are compound, with three leaflets, and the plant can grow up to 10 meters long. The flowers of the plant are small and white, and the fruits are pods that are about 4 to 7 cm long and 1 to 1.5 cm wide. The pods contain small, red seeds that are toxic to humans and animals. The plant's bark is reddish-brown while the roots and stems are dark brown.
Derris stuhlmannii is a fascinating plant with various uses in traditional African medicine and agriculture. Despite its toxicity, the plant's insecticidal and piscicidal properties have earned it a reputation as a useful tool for subsistence farmers and fishermen in Africa.
Light Requirements
Derris stuhlmannii (Taub.) Harms requires a significant amount of sunlight to thrive. Therefore, it grows optimally in well-lit areas where it can receive consistent and direct sunlight. However, it can also tolerate moderate shade, especially during the hottest part of the day.
Temperature Requirements
The ideal temperature range for Derris stuhlmannii (Taub.) Harms growth is between 20°C and 30°C. It cannot tolerate extreme temperatures, especially frost, which can damage leaves and ultimately lead to plant death. Therefore, it is recommended to plant it in areas with moderate temperature ranges, preferably within the tropics.
Soil Requirements
Derris stuhlmannii (Taub.) Harms thrives in a well-drained soil rich in nitrogen and phosphorous minerals. It can adapt to any soil type, including sandy, loamy, or clayey soil, as long as drainage is efficient. However, it grows optimally in deep, fertile, and well-aerated soils with a pH level of between 5.5 and 6.5. In addition, it requires regular watering to keep the soil moist.
Cultivation Methods
Derris stuhlmannii (Taub.) Harms is a tropical plant and grows well in warm, humid conditions. It prefers well-drained soils and can thrive in sandy or loamy soils with a pH of 5.0-7.5. The plant requires moderate sunlight and can grow either as an epiphyte or a climber. The ideal temperature range for cultivation is between 21-30°C.
The plant can be propagated from seeds or stem cuttings. When starting with seeds, they should be soaked in water for 24 hours before sowing. The seeds should be placed in a well-draining potting mix and covered lightly. For stem cuttings, select a healthy stem and make a clean cut just below a node. The cutting should be about 15-20 cm in length and treated with rooting hormones before planting in a well-draining medium.
Watering Needs
Derris stuhlmannii (Taub.) Harms requires regular watering, especially during the growing season. The soil should be kept moist, but not waterlogged. Overwatering can lead to root rot, so it is important to ensure adequate drainage. The frequency of watering can be reduced during the dormant season, but the soil should never dry out completely.
Fertilization
The plant benefits from regular fertilization with a balanced fertilizer. The fertilizer should be applied every two weeks during the growing season. The amount of fertilizer applied should be based on the size of the plant and set according to the manufacturer's instructions. Over-fertilizing can damage the plant, leading to stunted growth and reduced flowering.
Pruning
Pruning is not necessary for Derris stuhlmannii (Taub.) Harms, but can be done to control its size or shape. Remove any dead or diseased branches regularly to ensure the health of the plant. In addition, pruning can be done to promote branching and encourage more flowers. The best time to prune is during the dormant season, but it can be done at any time of the year with minimal impact on the plant.
Propagation of Derris stuhlmannii (Taub.) Harms
Derris stuhlmannii (Taub.) Harms is commonly propagated through seeds or stem cuttings.
Propagation through seeds
The seeds of Derris stuhlmannii (Taub.) Harms need to be collected when the pods are dry and brown. After collecting the seeds, they need to be cleaned and soaked in water for 24 hours to soften the seed coat. Once seeded, the seeds are then sown in a nursery bed or container filled with well-draining soil. The seeds should be planted at a depth of 1-2 cm and watered regularly. Germination usually occurs within 1-2 weeks.
Propagation through stem cuttings
The stem cuttings of Derris stuhlmannii (Taub.) Harms should be collected from healthy and disease-free plants. The cuttings should be taken from the current season's growth, and they should have 2-3 nodes. The cuttings should be taken in the early morning and immediately placed in a container filled with water. The cuttings should then be treated with rooting hormones to promote root growth. After that, the cuttings should be planted in a well-draining soil in a nursery bed or container. The cuttings should be watered regularly and kept in a humid environment until the roots are established.
Disease and Pest Management of Derris Stuhlmannii Plants
Derris stuhlmannii (Taub.) Harms is a tropical plant that grows in humid and warm environments. It is commonly used as a botanical insecticide and also has several medicinal properties. However, it is susceptible to different diseases and pests that can reduce plant growth and productivity. Therefore, it is essential to manage these challenges to ensure healthy and productive plants.
Common Diseases Affecting Derris Stuhlmannii Plants
The following are some of the common diseases that affect Derris stuhlmannii plants:
Fungal Leaf Spot
Fungal leaf spot is a common disease that affects Derris stuhlmannii plants. It is caused by fungi that thrive on the plant's leaves, leading to the formation of lesions. The leaves can turn yellow, and premature leaf drop can occur, leading to stunted plant growth and reduced productivity.
Root Rot
Root rot is a severe disease that affects Derris stuhlmannii plants. It is caused by fungi that attack plant roots, leading to decay and death. The symptoms include wilting, yellowing, and premature leaf drop.
Bacterial Wilt
Bacterial wilt is another severe disease that affects Derris stuhlmannii plants. It is caused by bacteria that attack the plant's vascular system, leading to wilting, yellowing, and premature leaf drop. The disease can spread rapidly and cause significant plant loss.
Pest Management of Derris Stuhlmannii Plants
The following are some of the common pests that affect Derris stuhlmannii plants:
Spider Mites
Spider mites are tiny pests that attack Derris stuhlmannii plants, sucking sap from the leaves, leading to yellowing and premature leaf drop. The infestation can spread rapidly, leading to significant plant loss.
Caterpillars
Caterpillars are another common pest that attacks Derris stuhlmannii plants. They can defoliate the plants, leading to stunted growth and reduced productivity.
Mealybugs
Mealybugs are soft-bodied pests that attack Derris stuhlmannii plants, leading to wilting, yellowing, and premature leaf drop. They produce a white, powdery substance that can attract ants and promote the growth of sooty mold.
Ways to Manage Diseases and Pests in Derris Stuhlmannii Plants
The following are some of the management practices that can be used to control diseases and pests in Derris stuhlmannii plants:
Use of Botanical Pesticides
Derris stuhlmannii plants contain several active compounds that can be used as a botanical pesticide to control pests. The extract from the roots of the plant contains rotenone, which is a potent insecticide. Botanical pesticides are a safer alternative to synthetic pesticides that can be harmful to the environment and human health.
Pruning and Crop Rotation
Pruning can help to remove diseased parts of the plants, reducing the spread of diseases. Crop rotation can also help to prevent the buildup of soil-borne pathogens that can cause diseases.
Maintain Proper Hygiene
Maintaining proper hygiene in the field can help to reduce the spread of diseases from one plant to another. This includes cleaning tools, equipment, and the field after harvesting.
Natural Predators and Beneficial Insects
Introducing natural predators and beneficial insects such as ladybugs, lacewings, and praying mantis can help to control pest infestation in the field.
Use of Organic Fertilizers
Organic fertilizers can help to promote plant growth and boost plant immunity to diseases and pests.
Implementing these management practices can help to control diseases and pests in Derris stuhlmannii plants, promoting healthy and productive plants.
