Overview
Rhamphicarpa angolense Engl., commonly known as the Angolan Witchweed or Angola Striga, is a parasitic plant species belonging to the Orobanchaceae family. Originally discovered in Angola, this plant is now found in other African countries such as Botswana, Zambia, and Zimbabwe. The plant is considered a significant weed that parasitizes crops, ultimately reducing agricultural yield in the regions where it is prevalent.
Appearance
The plant has a slender stem, which can grow up to a height of 70 cm. The leaves are alternate, lanceolate, green, and have a smooth texture. The flowers are delicate and white, growing in a terminal raceme. The fruit is a capsule with numerous tiny seeds that can survive in the soil for an extended period until they find a suitable host to parasitize.
Uses
The Rhamphicarpa angolense Engl. is primarily considered a weed and has no known beneficial uses. It is parasitic and can cause significant damage to food crops such as maize, millet, and sorghum, leading to crop losses and reduced food availability in the affected regions. The plant has no medicinal or culinary uses, and its control and eradication remain a significant challenge to farmers in the regions where it is rampant.
Light Requirements
Rhamphicarpa angolense Engl. requires full sun exposure to grow well. The plant will not thrive in shaded areas as it needs direct sunlight for optimal growth. When planting, it's important to choose a location that receives at least six hours of direct sunlight per day.
Temperature Requirements
This plant grows best in warm to hot temperatures between 25-30 degrees Celsius. Cold temperatures can stunt the growth of the plant and make it more susceptible to diseases. It's important to provide adequate shelter and cover to protect it from frost or cold winds.
Soil Requirements
The soil requirements of Rhamphicarpa angolense Engl. are well-drained, sandy loam with a pH between 5 and 6. The soil should not be too compact as this can limit root growth. Adding organic matter to the soil before planting can help the plant thrive by improving soil fertility and drainage.
Cultivation Methods
Rhamphicarpa angolense Engl. is a perennial herb commonly grown in tropical and subtropical regions. The plant prefers well-drained soils and requires partial shade to full sun exposure for optimal growth. The best way to cultivate R. angolense is by sowing the seeds directly into the soil or propagating from stem cuttings. When planting the seeds, ensure they are not buried too deeply as this may hinder germination.
Watering Needs
R. angolense requires moderate watering, especially during the dry seasons. Too much water may cause root rot, which can damage the plant. It is important to water the plant early in the morning or late in the evening to prevent rapid evaporation. Ensure that the soil is moist but not waterlogged to avoid suffocating the roots.
Fertilization
Fertilization is essential for the proper growth and development of R. angolense. The plant requires a balanced fertilizer with a Nitrogen-Phosphorous-Potassium (NPK) ratio of 10:10:10. Apply the fertilizer at the base of the plant during the growing season, which is usually in the rainy season. Too much fertilizer can lead to excessive growth and weak stems, which can make the plant susceptible to pests and diseases.
Pruning
Pruning R. angolense is essential to promote bushy growth and maintain the plant's shape. However, only light pruning is necessary as excessive pruning can damage the plant or reduce the yield. Prune the plant in the early stages of growth to encourage side shoots to grow and remove any dead or diseased branches. Use clean and sharp pruning tools to avoid causing damage to the plant
Propagation Methods for Rhamphicarpa angolense Engl.
Rhamphicarpa angolense Engl., commonly known as Angolan cowpea, is a leguminous plant that grows up to 1.5 meters tall. It is a seldom-cultivated plant that is native to Angola, Southern Africa. The plant is propagated using the following methods:
Seeds Propagation:
The best method of propagating Rhamphicarpa angolense Engl. is through the use of seeds. The seeds of the plant can be collected from matured pods by handpicking. The seeds should be dried and stored in a cool and dry place before planting.
To plant the seeds, a seedbed is prepared by loosening the soil and adding organic matter to make it rich in nutrients. The seeds are then sown in the seedbed and covered lightly with soil. Water the seedbed using a watering can or a hosepipe with a fine rose attachment, and keep the soil moist until germination. The seedlings can be transplanted into individual pots or directly to the field after reaching 2 to 3 inches tall.
Cutting Propagation:
Another method of propagating Rhamphicarpa angolense Engl. is through cuttings. The plant can be propagated using stem cuttings that are 4 to 6 inches long and free from diseases and injuries. Cut the stem from the parent plant using a sharp, clean knife or a pruning shear. The leaves of the cutting should be trimmed to reduce the water loss through transpiration.
Prepare a rooting hormone solution and dip the cuttings into it for a few seconds. The cutting is then planted in a good quality potting mix that is moist but not too wet. Cover the pot with a clear plastic bag or a polythene sheet to create a humid environment and reduce water loss. The cutting should root and produce new leaves within two to three weeks.
Division Propagation:
Rhamphicarpa angolense Engl. can also be propagated through division. This method involves digging up the parent plant and dividing it into smaller sections that have well-formed roots and shoots. Use a sharp, clean knife or a spade to divide the plant into sections, ensuring that each section has an equal amount of roots and shoots. Plant each section in a well-prepared soil, water it thoroughly, and keep it moist for the first few days until new growth appears.
In conclusion, Rhamphicarpa angolense Engl. can be propagated using three methods; seeds, cuttings, and division. Seed propagation is the most recommended method, while cutting and division are alternative methods that can be used to propagate the plant.
Disease and Pest Management for Rhamphicarpa angolense Engl.
Rhamphicarpa angolense Engl. species belong to family Orobanchaceae. The plant is generally resistant to diseases and pests, making it an excellent option for gardens and landscapes. However, it is still essential to take preventive measures against potential issues.
Common Diseases
Even though Rhamphicarpa angolense is resistant to many diseases, it is still susceptible to some, such as fungal infections. The plant may suffer from leaf spots or rust if it is exposed to prolonged periods of high humidity. Additionally, damping-off or root rot can occur in young seedlings if the soil remains too wet.
Disease Management
To prevent fungal infections, it's essential to ensure that the air circulates freely within the plant canopy, and the foliage is not excessively wet. Watering should be done in the morning to allow enough time for the leaves to dry during the day. In the case of damping-off, providing adequate space between the seedlings, reducing watering, and improving drainage can help control the issue. The use of fungicides may also be necessary in severe cases.
Common Pests
Rhamphicarpa angolense is also susceptible to pest attacks, primarily by aphids and whiteflies. These pests feed on plant sap, leading to stunted growth and yellowing of leaves. Scale insects may also affect the plant by attaching themselves to the stem and foliage.
Pest Management
To control aphids and whiteflies, the use of insecticides or predators, such as ladybugs or lacewings, can be effective. For the scale insect, physical removal or the use of horticultural oils or insecticides can be used. It's also beneficial to regularly inspect the plant for the presence of pests and to take action promptly if noticed.
Overall, Rhamphicarpa angolense is a remarkably resistant plant, but it's still important to manage and mitigate potential disease and pest issues to help maintain a healthy and thriving plant. Proper maintenance, such as regular watering and fertilization, can also contribute to preventing such issues from occurring.
