Origin
Dioscorea montana Eckl. & Zeyh. ex R.Knuth var. glauca R.Knuth, commonly known as the Glauca mountain yam, is a species of perennial herbaceous vine that is native to the eastern regions of South Africa.
Common Names
The Glauca mountain yam is widely known by different names in different parts of the world. In South Africa, it is commonly called "Glauca bergpatat," while in Zimbabwe, it is known as "Mumbeere."
Uses
The Glauca mountain yam is an essential crop for the communities living in eastern South Africa as it is a significant source of food. People consume the tubers by boiling, roasting or frying them. The yam is rich in starch and is also high in dietary fibre.
Besides being a food crop, the plant has medicinal properties, and different parts of the plant are traditionally used to treat a variety of ailments. The tubers are used to treat stomach aches and diarrhoea, while the leaves are used to treat skin infections.
General Appearance
The Glauca mountain yam is a climbing plant with a woody stem that can grow up to 5 meters long. It has a heart-shaped, glossy green leaves that are about 7 to 15 cm long. The plant produces small, greenish-yellow flowers that are unisexual. The yam tubers are cylindrical, elongated with a slight curve, and can grow up to 25 cm long and 10 cm in diameter.
The Glauca mountain yam is an attractive plant, with a natural aesthetic appeal that is suitable for ornamental purposes in gardens.
Light Requirements
As a tropical to subtropical species, Dioscorea montana var. glauca requires plenty of sunlight to grow and thrive. It is recommended to grow this plant in an area that receives at least six hours of direct sunlight per day. However, it is also essential to protect it from intense sunlight during the hottest part of the day, which could otherwise cause sunburn.
Temperature Requirements
Dioscorea montana var. glauca thrives in warm temperatures between 20°C to 30°C. During winter, it can tolerate a temperature drop up to 10°C, but frost can damage the plant. Therefore, it is critical to maintain a moderate temperature range throughout the year and protect the plant from extreme weather conditions.
Soil Requirements
The ideal soil for Dioscorea montana var. glauca is well-drained, fertile, and rich in organic matter. The plant prefers a slightly acidic to neutral soil with a pH range of 6.0 to 7.0. However, it can tolerate a broad range of soils, including sandy, loamy, and clayey. It is essential to avoid waterlogged soils as they can cause root rot and hinder the plant's growth.
Cultivation Methods
Dioscorea montana Eckl. & Zeyh. ex R.Knuth var. glauca R.Knuth is a perennial plant that grows well in moist, well-drained soil with high organic matter content. The plant requires partial to full sunlight and prefers a temperature range of 20-25°C. The best way to propagate Dioscorea montana is by seed or through the division of tubers.
Watering Needs
It is vital to keep the soil consistently moist to ensure optimum growth and development of Dioscorea montana. However, it is also essential to avoid overwatering as it can cause root rot. Water the plant regularly but ensure the soil surface is dry before the next watering session. During the dry season, increase the frequency of watering to ensure the soil remains moist.
Fertilization
Dioscorea montana requires regular fertilization to thrive. It is best to apply a balanced fertilizer, rich in organic matter, during the growing phase. Apply the fertilizer at the beginning of the growing season and repeat the application every four weeks until the end of the growing season. It is critical to follow the manufacturer's instructions when applying fertilizers.
Pruning
Dioscorea montana doesn't require regular pruning; however, in the event of overgrowth, pruning is necessary. Prune the plant to remove dead or diseased leaves and stems to prevent the spread of infections to healthy sections. Dioscorea montana is a climbing plant that needs support to grow; therefore, occasional tying of stems to trellises or poles is necessary.
Propagation Methods for Dioscorea montana Eckl. & Zeyh. ex R.Knuth var. glauca R.Knuth
Dioscorea montana Eckl. & Zeyh. ex R.Knuth var. glauca R.Knuth, commonly known as the mountain yam, is propagated through two methods: seed propagation and vegetative propagation.
Seed Propagation
Seed propagation is a common method for the propagation of mountain yam. Seeds are obtained from mature fruits and are sown in the soil during the sowing season. The seeds should be sown at a depth of 5-7 cm in soil that is well-drained and fertile. The seedlings emerge from the soil within 10-15 days from sowing. They are then transplanted to a permanent location when they attain a height of 10-15 cm and have developed about 2-3 leaves.
Vegetative Propagation
The mountain yam can also be propagated vegetatively through the use of tubers. The technique used is usually referred to as stem cutting propagation, making use of the healthy parent plant. The tuber is cut into numerous sections, each with well-developed vegetative buds. The cuttings are then planted in soil with about two-thirds of their length embedded in the soil. The soil should be well-drained and rich in organic matter. The time of planting is determined by the region's climate. The vegetative cuttings can be planted after the rainy season or when there is sufficient rain. It takes approximately four-six months before the stem cuttings can begin to sprout new shoots.
Disease and Pest Management for Dioscorea montana var. glauca
Dioscorea montana var. glauca is susceptible to various diseases and pests, which can cause significant damage to the plant. Below are some of the common diseases and pests that might affect the plant and ways to manage them.
Diseases
Anthracnose: This fungal disease is characterized by the appearance of yellow spots with reddish-brown edges on the leaves. It can cause defoliation and reduce plant vigor. To manage anthracnose, remove and destroy infected leaves, and apply a fungicide with active ingredients such as copper or sulfur.
Root Rot: This disease is caused by fungal pathogens, and it affects the plant's roots, causing them to turn brown and mushy. It can lead to stunted growth and wilting. To manage root rot, avoid overwatering the plant, ensure proper drainage, and apply a fungicide with active ingredients such as mefenoxam or thiophanate-methyl.
Pests
Scale Insects: These tiny insects are usually found on the undersides of the leaves, and they can cause yellowing and wilting. To manage scale insects, remove them manually, and apply insecticidal soap or neem oil to the affected leaves.
Caterpillars: The caterpillars of various moth species can feed on the plant's leaves, causing defoliation. To manage caterpillars, remove them manually and apply a biological pesticide with active ingredients such as Bacillus thuringiensis.
Spider Mites: These small pests feed on the plant's leaves and cause yellowing and wilting. To manage spider mites, spray the plant with a strong jet of water to dislodge them, and apply an insecticidal soap or neem oil.
In conclusion, regular monitoring and proactive management can help prevent or reduce the impact of diseases and pests on Dioscorea montana var. glauca.
