Overview of Zanthoxylum usambarense
Zanthoxylum usambarense, also known as Zanthoxylum gilletii, is a deciduous tree native to Africa, specifically East African countries such as Tanzania, Uganda, and Kenya. The plant belongs to the citrus family, Rutaceae, and is commonly referred to as the "African Prickly Ash"
Appearance of Zanthoxylum usambarense
Zanthoxylum usambarense grows up to 40 meters in height and has a greyish-brown bark. The leaves are compound, alternate, and have a glossy dark green color, with a size of around 5-12 cm. Its flowers are small and white, with a diameter of around 2-4 mm. The fruits are yellow to orange, round, and small in size, measuring around 5-8 mm in diameter.
Uses of Zanthoxylum usambarense
The bark, leaves, and fruits of Zanthoxylum usambarense are commonly utilized for medicinal purposes in traditional African medicine. The tree's bark and fruits are used to treat various ailments such as stomach aches, toothache, asthma, and rheumatism. Moreover, the fruit is used to add flavor to food, particularly meat.
The tree's bark extracts have also been utilized for various medicinal purposes, with studies showing that the extracts possess anti-inflammatory and analgesic properties. The bark also contains alkaloids, coumarins, and flavonoids, which have been found to be effective in treating malaria.
Additionally, Zanthoxylum usambarense is also used for its insecticidal properties. The plant's extracts have been found to have insect repelling qualities, which protect stored food grains from insect attacks.
Zanthoxylum usambarense is also cultivated as an ornamental plant.
Growth Conditions of Zanthoxylum usambarense
Zanthoxylum usambarense (Engl.) Kokwaro is a plant that belongs to the family Rutaceae and is commonly known as the African prickly ash or the Sichuan pepper. It is a tree that is native to the Eastern arc mountains of Tanzania and has a wide range of growth conditions.
Light Conditions
Zanthoxylum usambarense requires full sun to partial shade for optimal growth. It can tolerate shade but does not grow as well. It is important to note that too much direct sunlight can cause leaf scorch, so it is recommended to provide some partial shade during the hottest part of the day.
Temperature Requirements
Zanthoxylum usambarense prefers a warm tropical environment with a temperature range of 18°C to 25°C (65°F to 77°F). It can tolerate temperatures as low as 10°C (50°F) but does not grow well in environments with temperatures above 30°C (86°F). The plant can also tolerate a wide range of humidity levels but prefers moderate to high humidity.
Soil Requirements
The plant prefers well-drained soils that are rich in organic matter. It can grow in a variety of soil types, including loam, clay loam, and sandy loam. However, it does not tolerate water-logged soils. The pH of the soil should be between 5.5 and 7.5. It is important to note that the plant requires regular watering during the growing season, but the soil should be allowed to dry out slightly between watering.
In conclusion, providing optimal growth conditions for Zanthoxylum usambarense (Engl.) Kokwaro is critical for the plant to thrive. The plant thrives in a warm tropical environment with full sun to partial shade. The soil should be well-drained and rich in organic matter with a pH range of 5.5 to 7.5. With the proper conditions, the African prickly ash can be a beautiful addition to any garden or landscape.
Cultivation methods
Zanthoxylum usambarense thrives in both full sun and partial shade. It requires well-draining soil and prefers soil pH between 5.5 and 7.0. The plant can be propagated by seeds, cuttings, or by layering.
Watering needs
Regular watering during the growing season is crucial, but the plant can tolerate short periods of drought. However, waterlogging should be avoided as it can cause root rot.
Fertilization
To optimize growth, the plant should be fertilized at least once a year, preferably in early spring. Use a balanced fertilizer, such as 10-10-10 or 12-12-12, and follow the manufacturer’s instructions on the label. Over-fertilization can burn the plant’s roots.
Pruning
Zanthoxylum usambarense requires occasional pruning to maintain its shape and promote new growth. Pruning should be done in the dormant season, from late winter to early spring. Dead or damaged branches should be removed, as well as any crossing or rubbing branches. The plant can be pruned to a desired size and shape, but avoid cutting back more than one-third of the total plant height in one pruning session.
Propagation of Zanthoxylum usambarense (Engl.) Kokwaro
Propagation is an essential part of cultivating Zanthoxylum usambarense. While the methods may vary from one plant to another, the following are some of the commonly used ways to propagate this plant.
Seeds Propagation
Zanthoxylum usambarense can be propagated through seeds. The seeds should be collected from ripe fruits and sown in the seedbeds. It is advisable to soak the seeds in water for about 24 hours before sowing. The ideal temperature for germination is between 20-25°C. Seedlings should appear after 2-3 weeks, and they can be transplanted into individual pots after the first true leaves appear.
Cuttings Propagation
Zanthoxylum usambarense can also be propagated through stem cuttings. This method involves cutting 10-15 cm long stems from a healthy parent plant. The leaves on the lower half of the stem should be removed, and the cutting should be treated with rooting hormone powder or gel. The cutting should then be placed in a pot filled with well-draining soil mix and kept in a warm and humid place with filtered light. After a few weeks, new growth should appear, indicating rooting.
Air Layering Propagation
Air layering is another method used to propagate Zanthoxylum usambarense. This technique involves making a small cut on a branch to expose the cambium layer. A rooting hormone is then applied on the cut before wrapping moist sphagnum moss around it and covering it with plastic. The moss should be kept moist, and after a few weeks, new roots should have formed. The rooted section of the plant can then be cut off and potted, while the parent plant continues to grow.
Disease and Pest Management for Zanthoxylum usambarense (Engl.) Kokwaro
Zanthoxylum usambarense (Engl.) Kokwaro, commonly known as the African Prickly Ash, is a tree species that belongs to the Rutaceae family. It is a medicinally important plant that contains several active compounds including alkaloids, flavonoids, and terpenoids. The plant is largely grown in tropical and subtropical regions to support its medicinal and ornamental purposes. However, like any other plant species, it is also susceptible to diseases and pests that can lead to reduced yields or total destruction.
Common Diseases
Z. usambarense is susceptible to several diseases that can significantly impact its overall health and yield. Some of the most common diseases that affect the plant include:
- Anthracnose: a fungal disease that causes leaf spots, defoliation, and blight.
- Root rot: caused by soil-borne fungi that cause the roots to rot, leading to stunted growth and plant death.
- Leaf spot: caused by a fungal organism that causes circular, water-soaked lesions on the leaves, leading to leaf drop and reduced yield.
- Powdery mildew: a fungal disease that results in white, powdery growth on leaves, leading to reduced photosynthesis and stunted growth.
Disease Management
Frequent scouting and monitoring of the plants is important to detect any disease symptoms early. Some of the ways to manage the diseases include:
- Sanitation: practice good sanitation by removing and destroying all infected plant parts, including leaves, stems, and roots, to prevent the spread of the disease to healthy plants.
- Use of resistant cultivars: choose a disease-resistant variety to reduce susceptibility to some of the common diseases.
- Chemical control: in severe cases, chemical control with appropriate chemicals can be used to manage the diseases. However, care should be taken to minimize the impact on the environment and human health.
Common Pests
Z. usambarense is also susceptible to several pests that can cause significant yield losses. Some of the common pests include:
- Scale insects: they pierce the leaves and extract sap, causing yellowing, stunted growth, and leaf drop.
- Caterpillars: they feed on the leaves, causing defoliation and reduced yield.
- Mites: they suck sap from the leaves, causing yellowing and reduced yield.
- Termites: they feed on the roots, causing stunted growth and sometimes plant death.
Pest Management
The following are some of the management practices that can be used to control the pests:
- Mechanical control: handpicking of caterpillars and other larger pests can be effective in small-scale management.
- Cultural control: use of clean cultural practices such as proper crop rotation, removal of weed hosts, and proper spacing can reduce pest prevalence.
- Use of biological control: use of natural enemies such as predators and parasitoids can be effective in controlling pests.
- Use of chemical control: chemical control can be used in severe cases, but care should be taken to minimize the impact on the environment and human health.
