Origin
Rhus gerrardii var. latifolia Schönland is a species of shrub in the Anacardiaceae family. It is commonly found in the Western Cape Province of South Africa, particularly on the sandstone slopes of the Cape Fold Mountains and the Cederberg Wilderness Area.
Common Names
The plant is commonly known as the Mountain Karee or Mountain Poison Ivy in English, and Bergkaree in Afrikaans.
Uses
The Mountain Karee is a traditional medicine plant that has been used by local communities for centuries to treat various ailments such as wounds, gastrointestinal problems, and fever. The bark of the plant contains tannins and has astringent properties that can help stop bleeding and heal wounds faster. Additionally, the plant is commonly used for landscaping purposes due to its attractive appearance and ability to grow in harsh conditions.
General Appearance
The Mountain Karee is a small, dense, evergreen shrub that typically grows up to 3 meters tall. It has a rounded, spreading growth habit and produces small yellow-green flowers that bloom in spring and summer. The leaves of the plant are pinnate, with 3-5 leaflets that have serrated edges. The bark is grey-brown and has a rough texture.
Growth Conditions for Rhus gerrardii var. latifolia
Light Requirement: Rhus gerrardii var. latifolia is a sun-loving plant that requires full sunlight to thrive. Therefore, it is ideal to plant it in an open area where it can receive at least six hours of direct sunlight per day.
Temperature Requirement: This plant can tolerate a wide range of temperatures, provided the soil is well-draining. It prefers a warm and dry climate, making it suitable for summer and Mediterranean gardens. In winter, it can survive temperatures as low as -5°C but may require
Soil Requirement: The soil should be well-draining and not waterlogged. It should also be rich in organic matter and slightly acidic with a pH range of 5.5-6.5. Sandy or loamy soils with good moisture retention are optimal soil types for Rhus gerrardii var. latifolia. Additionally, the plant prefers soils that have good aeration and are not compacted.
Water Requirement: This plant has moderate water requirements, and the soil should be kept evenly moist. However, it should not be overwatered as it can lead to root rot. During the growing season, it is recommended to give the plant a deep soak once a week, while in winter, it may require watering once a month.
Fertilizer Requirement: This plant requires minimal fertilization as it can fix its nitrogen from the air. However, a balanced, slow-release fertilizer can be applied during the growing season to improve growth and flowering. Fertilizers high in nitrogen should be avoided as they can promote vegetative growth at the expense of flowering.
Cultivation of Rhus gerrardii var. latifolia
Rhus gerrardii var. latifolia is a drought-resistant plant that can tolerate hot and dry conditions, as well as a range of soils. It prefers well-drained, sandy or loamy soils that are slightly acidic.
To cultivate Rhus gerrardii var. latifolia, start by choosing a location that receives full sun. This plant does not tolerate shade well, and insufficient sunlight can weaken its growth and resistance to pests and diseases. Dig a hole twice as wide as the container or root ball, and plant the Rhus gerrardii var. latifolia at the same level as it was growing in the container or nursery. Water thoroughly after planting and keep the soil moist until the plant establishes itself.
Watering Needs of Rhus gerrardii var. latifolia
Rhus gerrardii var. latifolia is a drought-tolerant plant that can survive long periods of dryness. However, it requires regular watering during its establishment phase, which can last up to a year. Water deeply once a week during the growing season and reduce watering during winter. Avoid watering the leaves and aim for the base of the plant to prevent fungal diseases.
Fertilization of Rhus gerrardii var. latifolia
Rhus gerrardii var. latifolia does not require frequent fertilization, as it can adapt to poor soils. However, adding compost or well-aged manure to the planting hole can provide nutrients that enhance growth and vigor. You can also apply a balanced, slow-release fertilizer in spring and fall to support the plant's needs. Avoid excessive use of nitrogen-rich fertilizers, as they can stimulate excessive foliage growth at the expense of flowering.
Pruning of Rhus gerrardii var. latifolia
Rhus gerrardii var. latifolia does not require pruning, but you can shape the plant or remove dead, damaged, or diseased branches as needed. Prune after flowering, using clean and sharp tools to avoid spreading infections. Wear gloves and long sleeves when handling the plant, as it can cause skin irritation in some people. Dispose of pruned branches in a safe manner, as they can be toxic or cause allergies.
Propagation of Rhus gerrardii var. latifolia
Rhus gerrardii var. latifolia can be propagated by seed, cuttings, or layering. Each method has its own advantages and disadvantages, depending on the grower's needs and preferences.
Seed Propagation
Seed propagation is a relatively easy and economical way to grow Rhus gerrardii var. latifolia. The seeds should be collected from mature fruits and cleaned of any pulp or debris. The cleaned seeds can be sown immediately or stored in a cool, dry place until planting time. The seeds should be sown in a well-draining seedling mix and kept moist until germination. Germination may take several weeks, and the seedlings should be kept in a warm, bright location with some protection from direct sunlight.
Cutting Propagation
Cutting propagation is a popular and efficient method for propagating Rhus gerrardii var. latifolia. Cuttings should be taken from healthy, mature plants during the dormant season, when the plant has shed its leaves. The cuttings should be about 8-10 inches long and taken from the current year's growth. Remove the leaves from the bottom half of the cutting and dip the cut end in rooting hormone. The cuttings should be planted in a well-draining rooting medium, kept moist, and protected from direct sunlight until they have rooted. It may take several weeks for the cuttings to root, after which they can be transplanted to their permanent location.
Layering Propagation
Layering propagation is a reliable and low-maintenance method for propagating Rhus gerrardii var. latifolia. In this method, a low-growing branch of the plant is bent down to the ground and buried in a shallow trench. The branch should be wounded slightly before it is buried to encourage rooting. The buried section of the branch should be kept moist, and roots will develop in several weeks. Once roots have formed, the new plant can be separated from the parent plant and transplanted to its permanent location.
Disease Management
Rhus gerrardii (Harv. ex Engl.) Diels var. latifolia Schönland, commonly known as Rhus, is susceptible to various fungal and bacterial diseases, leading to defoliation and stunted growth. The following are common diseases that affect Rhus and management strategies:
Powdery Mildew
Powdery mildew is a fungal disease that affects Rhus leaves, leaving a white powdery substance on the leaves' upper surface. The disease can spread rapidly, leading to defoliation, which can weaken the plant and reduce its productivity. Management strategies for powdery mildew include:
- Removing infected parts of the plant and disposing of them away from the garden to prevent the spread of the fungus.
- Watering Rhus early in the day to prevent evening and night dew that fosters fungal growth.
- Applying fungicides such as sulfur, copper, or neem oil early in the season or after pruning to prevent the disease from spreading.
Anthracnose
Anthracnose is a fungal disease that affects young Rhus leaves, causing them to curl and distort in shape. The disease can spread to the older leaves, leading to defoliation and reduced productivity. Management strategies for anthracnose include:
- Removing infected plant parts to prevent the spread of the disease.
- Pruning Rhus to encourage proper air circulation and sunlight penetration, which helps reduce fungal growth.
- Applying fungicides such as copper or chlorothalonil to protect the plant from the disease.
Pest Management
Rhus gerrardii (Harv. ex Engl.) Diels var. latifolia Schönland is susceptible to various insect pests that can cause significant damage to the plant. The following are common pests that affect Rhus and management strategies:
Scale Insects
Scale insects suck sap from Rhus leaves, causing the leaves to yellow and weaken the plant. The insects secrete a sticky substance that facilitates the growth of sooty mold, leading to reduced productivity. Management strategies for scale insects include:
- Pruning Rhus to encourage air circulation and sunlight penetration, which helps reduce insect growth.
- Using natural enemies such as ladybugs or parasitic wasps that prey on scale insects.
- Applying horticultural oil or insecticidal soap to suffocate and kill the insects.
Aphids
Aphids suck sap from Rhus leaves, causing the leaves to curl and distort in shape. The insects also secrete a sticky substance that facilitates the growth of sooty mold, which reduces productivity. Management strategies for aphids include:
- Using natural enemies such as ladybugs, hoverflies, or lacewings that prey on aphids.
- Placing reflective mulches on the ground near Rhus to deter aphids from infesting the plant.
- Using insecticidal soap or neem oil to suffocate and kill the insects.
