Origin
Olea capensis L. subsp. welwitschii (Knobl.) Friis & P.S.Green, commonly known as the Cape olive, is a species of plant that belongs to the Oleaceae family. It is native to the eastern part of South Africa, including Zimbabwe, Mozambique, and Swaziland.
Common Names
The Cape olive is known by several common names, including the wild olive, mountain olive, and African olive. In South Africa, it is also referred to as isiHocha, umNquma, and umNquma-wamaqanda in Xhosa, Zulu, and Ndebele languages, respectively.
Uses
The Cape olive has several uses, both cultural and medicinal. The tree’s bark is used traditionally to treat various ailments, including stomach upsets, respiratory infections, and skin conditions. The leaves are crushed to make a paste used for treating wounds and as a cosmetic to relieve itching and pain. The oil extracted from the tree's fruit is used in soap-making and as a cooking oil.
General Appearance
The Cape olive is a small to medium-sized tree that grows up to 7 meters in height. It has a straight trunk with smooth, greyish-brown bark. The leaves are evergreen, shiny, and sparsely arranged on the branches, oval in shape, and about 3-7 centimeters (1.2-2.8 inches) long. The tree produces small, round fruit, about 10 to 20 millimeters in diameter, that are initially green, turning black when ripe.
Light Requirements
Olea capensis L. subsp. welwitschii require full sun to partial shade for optimal growth. They should be exposed to at least 6 hours of direct sunlight every day. Lack of sufficient light may cause stunted growth and poor production of fruits.
Temperature Conditions
This subspecies thrives in warm and hot climates. The optimal temperature range is between 20°C to 30°C. They are not frost tolerant and will not survive in temperatures below 10°C. Extreme heat can also be detrimental to their growth, so it's important to ensure adequate moisture in such conditions.
Soil Requirements
Olea capensis L. subsp. welwitschii prefer well-draining soils that are rich in organic matter. The soil pH should be between 5.5 and 8.5. They are adapted to grow in a range of soil types, from sandy soils to clayey soils. However, it is important to note that waterlogged soils should be avoided as they may lead to root rot and plant death. Regular fertilization with appropriate nutrients is beneficial for this subspecies.
Cultivation methods for Olea capensis L. subsp. welwitschii (Knobl.) Friis & P.S.Green
Olea capensis L. subsp. welwitschii requires full sun to partial shade and a well-draining soil. It is drought tolerant but needs occasional watering during periods of prolonged dryness. It is also tolerant of hot temperatures and sandy soils.
The plant can be propagated from seeds or cuttings. Seeds should be sown in a seedbed during early spring, and the young plants should be transplanted into individual pots before planting them outside. Cuttings should be taken from semi-hardwood in late summer and rooted in sandy soil or a mixture of perlite and peat.
Watering needs for Olea capensis L. subsp. welwitschii (Knobl.) Friis & P.S.Green
Olea capensis L. subsp. welwitschii is tolerant of drought but should be watered occasionally during periods of prolonged dryness. The plant's watering needs can be determined by checking the soil moisture levels using a moisture meter or by checking the soil's dryness with the finger test.
When watering, ensure that the soil is well-draining and the water penetrates deeply into the roots. Avoid overwatering as this can lead to root rot and fungal diseases.
Fertilization of Olea capensis L. subsp. welwitschii (Knobl.) Friis & P.S.Green
Olea capensis L. subsp. welwitschii does not require frequent fertilization, but a slow-release fertilizer can be applied during the growing season to promote healthy growth. The fertilizer should be high in nitrogen to encourage leafy growth.
Organic fertilizers such as compost or manure can also be used but should be applied sparingly as they can lead to the accumulation of salts in the soil over time.
Pruning of Olea capensis L. subsp. welwitschii (Knobl.) Friis & P.S.Green
Olea capensis L. subsp. welwitschii requires minimal pruning, but it can be done to maintain the plant's shape and size. Pruning should be done during the dormant season, which is typically in late winter or early spring.
To prune, remove any dead, diseased or damaged branches, and thin out any overcrowded branches. Maintain a central leader and remove any branches that are growing downwards or crossing other branches. Avoid pruning more than a third of the plant in one season.
Propagation of Olea capensis L. subsp. welwitschii
Olea capensis L. subsp. welwitschii (Knobl.) Friis & P.S.Green, commonly known as the Cape olive, is a shrub or small tree that is endemic to the southwestern Cape of South Africa. Propagation is an important aspect of growing this plant. The following are some of the propagation methods used for Olea capensis L. subsp. welwitschii:
Seed Propagation
One of the most common ways of propagating Olea capensis L. subsp. welwitschii is through seed propagation. The seeds should be sown in a well-draining potting mix that is kept moist but not waterlogged. The pot should be placed in a warm spot and covered with a clear plastic bag to retain moisture. Germination usually occurs within four to six weeks.
Cuttings
Olea capensis L. subsp. welwitschii can also be propagated through stem cuttings. The best time to take cuttings is during the spring or summer when the plant is actively growing. The cutting should be taken from a healthy, disease-free, and mature plant. The cutting should be about 10-15 cm long and consist of a stem with a few leaves attached. The bottom part of the cutting should be dipped in rooting hormone and planted in a well-draining potting mix. The pot should be placed in a warm, bright spot but out of direct sunlight. The cutting should root in about eight weeks.
Air Layering
Air layering is another propagation method that can be used for Olea capensis L. subsp. welwitschii. This method involves making a small incision and removing a ring of bark from the stem of the plant. The exposed area should be covered with a ball of moist sphagnum moss and wrapped with plastic wrap. The moss should be kept moist until roots sprout from the incision. The stem can then be cut below the rooted area and potted up.
Propagation of Olea capensis L. subsp. welwitschii can be a rewarding process. Whatever method is chosen, it is important to ensure that the plant is healthy, and the soil is well-draining to promote good root growth.
Disease Management
Olea capensis L. subsp. welwitschii is susceptible to a wide range of diseases that affect the plant's overall health. The most common diseases that affect Olea capensis L. subsp. welwitschii include:
- Cylindrocladium black rot: This disease is caused by the fungus Cylindrocladium parasiticum and is characterized by leaf spot, stem cankers, and black-brown discoloration on the base of stems. The best management practices for Cylindrocladium black rot include the use of resistant cultivars, proper irrigation, and sanitation practices to prevent the spread of infected plant material.
- Armillaria root rot: This disease is caused by the fungus Armillaria mellea and is characterized by root decay, wilting, yellowing foliage, and eventual death of the plant. The best management practices for Armillaria root rot include the use of resistant cultivars, proper irrigation, and sanitation practices to prevent the spread of infected plant material.
- Phytophthora root rot: Phytophthora root rot is caused by the fungus Phytophthora cinnamomi and is characterized by wilting, yellowing foliage, root decay, and eventual death of the plant. The best management practices for Phytophthora root rot include the use of resistant cultivars, proper irrigation, and minimizing soil moisture to prevent the disease from spreading.
Pest Management
Olea capensis L. subsp. welwitschii is also susceptible to a wide range of pests that can significantly impact plant health. The most common pests that affect Olea capensis L. subsp. welwitschii include:
- Olive lace bug: The olive lace bug is a sap-sucking insect that can cause significant damage to the foliage of Olea capensis L. subsp. welwitschii. The best management practices for olive lace bugs include the use of insecticidal soaps, proper pruning practices, and the use of biological controls such as predatory insects.
- Black scale: The black scale is a sap-sucking insect that can cause significant damage to the bark and leaves of Olea capensis L. subsp. welwitschii. The best management practices for black scale include the use of insecticidal soaps, proper pruning practices, and the use of biological controls such as predatory insects.
- Olive fruit fly: The olive fruit fly is a major pest of olive trees and can significantly impact fruit production in Olea capensis L. subsp. welwitschii. The best management practices for olive fruit fly include the use of pheromone traps, proper pruning practices, and the use of insecticidal sprays at the appropriate time.
