Description
Crotalaria excisa (Thunb.) Baker f. subsp. namaquensis Polhill is a perennial shrub or small tree that can grow up to 4 meters in height. Its stem and branches are hairy and can become woody as it ages. The plant has bright yellow flowers that are arranged in clusters at the top of the stem.
Origin and Distribution
Crotalaria excisa (Thunb.) Baker f. subsp. namaquensis Polhill is native to South Africa and can be found in regions such as the Western Cape, Northern Cape, and Namibia. It is also commonly found in other parts of Africa, including Botswana and Zimbabwe.
Common Names
The plant is commonly known as "Namib crotalaria" or "Namaqualand crotalaria."
Uses
Traditionally, the plant has been used as a medicinal herb to treat various ailments such as coughs, colds, and chest infections. Its leaves and roots have also been used to alleviate pain and inflammation. In addition to its medicinal properties, the plant is also used as a nitrogen-fixing crop and a source of high-quality forage for livestock.
However, caution should be exercised when consumed by livestock as it can cause toxicity due to its high levels of pyrrolizidine alkaloids.
Light Requirements
Crotalaria excisa subsp. namaquensis typically grows in areas with high light intensity. Therefore, it requires full sun exposure for optimal growth. The plant needs a minimum of six hours of direct sunlight per day, which is the equivalent of full sunlight.
Temperature Requirements
The plant prefers warmer temperatures and grows better in tropical and subtropical regions where temperatures range from 25-30°C. It cannot tolerate temperatures below 10°C and can suffer from frost damage.
Soil Requirements
Crotalaria excisa subsp. namaquensis prefers well-drained soil that is rich in organic matter. It can grow in a wide range of soils, including sandy or clay loam soils. The plant is highly tolerant of drought conditions, but it requires regular watering in hot and dry climates.
Cultivation methods for Crotalaria excisa (Thunb.) Baker f. subsp. namaquensis Polhill
Crotalaria excisa (Thunb.) Baker f. subsp. namaquensis Polhill is a drought-tolerant plant species that can grow in various soil types, including sandy, loamy, and well-draining soils. It is perfect for dry and warm climates, and it requires full sun exposure to thrive.
The best approach for planting Crotalaria excisa is to use seeds, which can be obtained from local nurseries or botanical gardens. Before sowing the seeds, soak them in warm water overnight to improve germination rates. Plant the seeds about 1 cm deep in the soil and ensure they are adequately spaced out to give room for their growth.
Watering needs for Crotalaria excisa (Thunb.) Baker f. subsp. namaquensis Polhill
Crotalaria excisa can survive in harsh conditions and does not require much watering. However, for the plant to grow healthy and produce good yields, it is paramount to provide the plant with enough water, especially during its germination stage.
The plant requires moderate watering, which is about 2-3 times a week, depending on the soil type. Generally, the soil should dry out before the next watering, and the type of soil will determine the amount of water required.
Fertilization needs for Crotalaria excisa (Thunb.) Baker f. subsp. namaquensis Polhill
Crotalaria excisa requires minimal fertilization as it has the ability to fix nitrogen from the atmosphere, which can enrich the soil. However, it is still important to provide adequate nutrients to the plant to improve its growth and yields.
The best way to fertilize Crotalaria excisa is to use organic fertilizers such as compost or well-rotted manure. Apply the organic manure at the beginning of the planting season, and repeat the process after every three months.
Pruning needs for Crotalaria excisa (Thunb.) Baker f. subsp. namaquensis Polhill
Crotalaria excisa requires minimal pruning as it grows into a small shrub, which does not require shaping. However, it is advisable to remove any dead or diseased parts of the plant to improve its overall health and productivity.
You may also prune the plant to control its overall size and shape. Regular pruning ensures that the plant maintains its full growth potential.
Propagation of Crotalaria excisa (Thunb.) Baker f. subsp. namaquensis Polhill
Crotalaria excisa (Thunb.) Baker f. subsp. namaquensis Polhill can be propagated through seeds or cuttings.
Propagating via Seeds
Seeds of Crotalaria excisa (Thunb.) Baker f. subsp. namaquensis Polhill can be collected from matured pods. Sow the seeds early in spring, right after the last frost. Prepare a well-draining potting mix and moisten the soil before sowing the seeds. Dibble the seeds into the mix and cover them with a thin layer of soil. Keep the soil moist but not wet until the seeds germinate, which typically takes 10 to 14 days. After germination, remove the weaker seedlings, leaving only one per pot. When the seedlings have grown to about 10 cm tall, transplant them to their permanent location in a well-draining soil mix. Water the newly transplanted seedlings regularly until they establish.
Propagating via Cuttings
Crotalaria excisa (Thunb.) Baker f. subsp. namaquensis Polhill can also be propagated through softwood cuttings. Take cuttings from the soft, new growth of a healthy parent plant during early spring or at the beginning of the growing season. Cuttings should be 10-15 cm in length and taken with a sharp, clean blade. Dip the bottom of the cuttings in rooting hormone to encourage root growth before planting them in a well-draining soil mix. Keep the soil moist and the cutting in a shaded area. Once roots have formed, which takes around 2 to 3 weeks, transplant the cutting to a permanent location in a well-draining soil mix.
Disease management
Crotalaria excisa (Thunb.) Baker f. subsp. namaquensis Polhill is susceptible to various diseases, including:
- Root rot: caused by soil-borne fungi, which can be prevented by keeping the soil well-drained. Infected plants should be removed to prevent the spread to healthy plants.
- Fungal leaf spot: characterized by small, circular spots on the leaves. It can be managed by removing the infected plant parts, improving air circulation, and avoiding overhead watering.
- Viral diseases: there are no known cure for viral diseases, and infected plants should be removed to prevent the spread to healthy plants.
To prevent diseases, it's essential to maintain good cultural practices, such as proper watering, pruning, and sanitation. Additionally, avoid planting Crotalaria excisa (Thunb.) Baker f. subsp. namaquensis Polhill in poorly-drained soil, and rotate crops to break disease cycles.
Pest management
Several pests can affect Crotalaria excisa (Thunb.) Baker f. subsp. namaquensis Polhill, including:
- Aphids: small insects that feed on the plant sap, causing deformation of leaves. Aphids can be managed by physical removal, such as washing them off with a strong spray of water, or the use of insecticidal soap.
- Thrips: tiny insects that feed on the plant cells, causing leaf deformation and discoloration. Thrips can be controlled using insecticidal soap or neem oil.
- Mites: microscopic pests that can cause bronzing or stippling of the leaves. They can be managed by applying insecticidal soap or neem oil.
It's important to monitor plants regularly for signs of pest infestation and take action at the first sign of an outbreak. Additionally, avoid over-fertilization, which can make plants more attractive to pests. Finally, ensure that the planting area is free from weeds and debris, which can harbor pests.
