Origin
Crotalaria laburnifolia L. subsp. laburnifolia is a perennial shrub that belongs to the family Fabaceae. It is native to South Africa and is commonly found in the eastern part of the country, particularly in the highlands of Mpumalanga and Limpopo provinces.
Common Names
This plant is commonly known as the Cape rattlepod, krukudjeri, kraakbos, and Cape laburnum.
Uses
The plant is used in traditional medicine to treat various ailments such as wounds, headaches, and stomach ailments. It is also used to relieve pain during childbirth. In addition, the plant is used as a natural pesticide and as a soil improver due to its nitrogen-fixing ability. The leaves and stems are also used to feed livestock.
General Appearance
Crotalaria laburnifolia L. subsp. laburnifolia is a woody shrub that can grow up to 2 meters in height. It has long, slender branches with dense foliage that is a characteristic light green color. The leaves are simple, alternate, and are oval-shaped. The plant produces long, thin, and erect seed pods that are cylindrical in shape and have a slight curve. The seeds inside the pods make a rattling sound when shaken, hence the name Cape rattlepod. The plant produces bright yellow flowers that are shaped like pea flowers and bloom throughout the summer months.
Light Requirements
Crotalaria laburnifolia L. subsp. laburnifolia requires full sun to grow properly. It is a tropical plant that originates from sub-Saharan Africa where it is exposed to direct sunlight. Therefore, it is essential to grow it in an area that receives at least 6 hours of direct sunlight each day.
Temperature Requirements
The plant thrives in warm temperatures and cannot tolerate frost or cold weather. Ideal growth temperature for Crotalaria laburnifolia L. subsp. laburnifolia ranges from 20-30°C (68-86°F). If temperatures drop below 10°C (50°F), the plant may become dormant, and growth will slow down significantly. The plant is not tolerant to high wind conditions, so it is essential to grow it in sheltered areas when possible.
Soil Requirements
Crotalaria laburnifolia L. subsp. laburnifolia grows well on soils that are well-draining and rich in organic matter. The soil should be slightly acidic to neutral with a pH range of 6.5-7.5. However, it is essential to note that the species can tolerate moderately low pH soils up to 5.5. The plant does not thrive in heavy soils like clays or soils that retain water for too long.
Cultivation Methods
Crotalaria laburnifolia is typically grown from seeds, which should be sowed in well-draining soil that is rich in nutrients. Ideally, the soil should have a pH between 5.5 and 7.0. The seeds should be sowed in a sunny location, and they should be covered with approximately 1/4 inch of soil. The soil should be kept moist but not waterlogged until the seeds germinate, which usually takes 1-2 weeks.
Watering Needs
Crotalaria laburnifolia plants require moderate watering, and care should be taken to avoid overwatering. The soil around the plant should be allowed to dry slightly between waterings, but it should never completely dry out. Watering once a week is generally sufficient, but this may vary depending on the climate and soil conditions.
Fertilization
Crotalaria laburnifolia plants benefit from regular fertilization during the growing season. A balanced fertilizer with an NPK ratio of 10-10-10 is a good choice. Fertilizer should be applied every two to three weeks during the growing season, following the instructions on the fertilizer packaging.
Pruning
Crotalaria laburnifolia plants benefit from occasional pruning to remove dead or damaged branches. Pruning is usually done in the late winter or early spring, before new growth begins. To prune, simply remove any dead or damaged branches with a sharp, clean pair of pruning shears. It is important to avoid cutting into healthy wood, as this can damage the plant.
Propagation of Crotalaria laburnifolia L. subsp. laburnifolia
Crotalaria laburnifolia L. subsp. laburnifolia, commonly known as the rattlebox plant, is a shrub that can be propagated both by seed and stem cuttings. Both methods have their advantages and disadvantages and may be suitable for different situations.
Seed propagation
To propagate Crotalaria laburnifolia L. subsp. laburnifolia by seeds, start by collecting mature seed pods once they have dried out and turned brown. The pods should be opened to remove the black, kidney-shaped seeds. Afterward, they should be soaked in hot water for at least 24 hours before sowing.
Before planting, the seeds can be treated with a fungicide to prevent fungal infections. It is also possible to scarify the seeds to improve germination rates. Seeds can be broadcasted directly on the soil surface, covered lightly with soil or grown in pots. If grown in pots, the pots should be kept in a warm place, and the soil should be kept moist until the seedlings emerge. The seedlings can be transplanted once two or three true leaves appear.
Stem cutting propagation
Propagation by stem cuttings involves taking a cutting of the stem, usually from the tips, and rooting it in sand, vermiculite, or a mix of both. The cuttings should be at least six inches long, with their lower leaves removed, and ideally, taken in spring or summer when the plant is actively growing.
Before planting, the cuttings should be dipped in rooting hormone to encourage root growth. The cuttings should then be planted in a well-draining medium and kept moist but not waterlogged. Covering the cuttings with a plastic bag can help to maintain high humidity levels during the rooting process. Strong roots should form within a few weeks, after which the young plant can be transplanted to a permanent location.
Disease and Pest Management for Crotalaria laburnifolia L. subsp. laburnifolia
Crotalaria laburnifolia L. subsp. laburnifolia, commonly known as rattlebox or golden raintree, can be susceptible to various diseases and pests. Here are some of the common ones and ways to manage them:
Diseases
Root rot: This infection is caused by various fungi that thrive in damp soil. Symptoms include wilting and yellowing of leaves, stunted growth, and the plant easily detaches from the soil. To manage this disease, reduce watering frequency and avoid watering the plant in the evening. Improve soil drainage and remove any affected plants and the surrounding soil.
Powdery mildew: Powdery mildew is caused by various fungi that spread through spores. Symptoms include white powdery spots on leaves, reduced growth, and eventual leaf drop. To manage this disease, keep the plant environment dry and increase airflow. Remove any infected parts and spray organic fungicides like neem oil or sulfur.
Leaf spot: This is a fungal infection that manifests as black, brown, or grey spots on leaves. It causes leaf drop, stunted growth, and reduced vigor. To manage this disease, remove the affected leaves and avoid overhead watering. Increase airflow and apply copper sulfate-based fungicides.
Pests
Mites: Mites thrive in hot and dry environments and feed on plant sap, causing leaves to appear stippled and discolored. To manage them, increase humidity levels and apply insecticidal soaps or horticultural oils.
Caterpillars: Caterpillars feed on the leaves, making irregular holes, and causing defoliation. They can be managed by physically removing them or applying bacillus thuringiensis-based pesticides.
Thrips: These tiny insects pierce the plant's stem and feed on the sap, leading to distorted leaves and reduced vigor. To manage them, increase humidity levels and release predatory insects like ladybugs or lacewings. You can also apply organic insecticides like neem oil.
Overall, preventative measures like ensuring proper soil drainage, environmental conditions, and cleanliness can help avoid diseases and pest infestations on Crotalaria laburnifolia L. subsp. laburnifolia. Early detection and management of any infestation can limit their spread to other plants.
