Unona Buchananii Engl.

Description of Unona buchananii Engl.

Unona buchananii Engl. is a small to medium-sized tree belonging to the family Annonaceae. It is native to West and Central Africa, and can be found growing in countries such as Cameroon, Gabon, and Nigeria.

Common Names

Unona buchananii is commonly referred to as African custard apple and sometimes as Buchanan's soursop. This is due to the fruit's similarity to the custard apple and soursop fruits, which are members of the Annonaceae family as well.

General Appearance

The Unona buchananii tree can grow up to 20 meters tall. It has a distinct brownish-grey bark and glossy green leaves that are alternate, oblong, and can be up to 20cm long. The flowers are small, yellowish-green in color, and emit a strong odor.

The fruit of the Unona buchananii tree is round to oblong and can grow up to 15cm in length. It has a greenish-yellow skin and a white, custard-like pulp inside. The fruit is edible and sweet when ripe, and is traditionally used in West and Central African cuisine to make juices and desserts.

Uses

Aside from its culinary uses, Unona buchananii has been found to have medicinal properties. The bark and leaves of the tree are used in traditional medicine to treat various ailments such as malaria, fever, and stomach conditions. Research has also shown that extracts from the tree have antioxidant and anticancer properties.

Unona buchananii is also used in agroforestry systems, as it is an important source of timber and non-timber forest products such as fruit and leaves for livestock feed. Moreover, the tree provides shade and helps to prevent soil erosion, making it an important component of sustainable land-use practices.

Light Requirements

Unona buchananii Engl. requires a moderate amount of sunlight for proper growth. It grows well in filtered light, partial shade, and shaded conditions. Direct sunlight may harm the plant, especially during the peak afternoon hours.

Temperature Requirements

The ideal temperature range for Unona buchananii Engl. ranges from 20°C to 30°C (68°F to 86°F). It thrives in warm and humid environments. Low temperatures (below 15°C or 59°F) and frosty conditions are not suitable for its growth.

Soil Requirements

The plant thrives in well-draining soils rich in organic matter. The ideal soil pH should range between 6.0 to 7.5. It does well in loamy, sandy, and clayey soils. However, it does not grow well in waterlogged or poorly-draining soils.

Cultivation

Unona buchananii Engl. is a tropical plant that requires a warm and humid environment to cultivate successfully. It thrives well in well-draining, fertile loam soil. Transplanting to a larger container should be done during the growing season, which is in spring. While the plant can be grown from seeds, propagating through cuttings is more effective.

Watering Needs

The plant prefers evenly moist soil and should be watered consistently to ensure the roots are well hydrated. However, overwatering can cause root rot and eventually lead to the death of the plant. Avoid letting the soil dry out completely between watering.

Fertilization

Unona buchananii Engl. requires regular fertilization to thrive. Use a balanced, slow-release fertilizer every month during the growing season. Be careful not to over-fertilize as this can damage the plant or weaken it against diseases and pests.

Pruning

Pruning is essential to maintain the shape and size of the plant, remove dead parts, and encourage new growth. It's advisable to prune after the flowering period and only remove the spent flowers and wilted leaves to promote the growth of new leaves and flowers.

Propagation of Unona buchananii Engl.

Unona buchananii Engl., also known as Buchanan’s torchwood, is propagated through seeds and stem cuttings. Here are the details of each propagation method:

Propagation through seeds

The seeds of Unona buchananii must be planted immediately after the fruit ripens. The fruit is a fleshy aggregate and contains numerous seeds. The ripe seeds are brown in color and approximately 0.9 cm in length.

To propagate Unona buchananii through seeds, the following steps are recommended:

1. Collect the ripe fruits from the plant.
2. Separate the seeds from the fruit pulp and wash them thoroughly in water.
3. Prepare a well-draining potting mix using loamy soil, sand, and organic matter.
4. Fill the pots with the prepared mix and plant the seeds 1 cm deep into the soil.
5. Water the soil until it becomes moist and place the pots in a partially shaded location.
6. The seedlings will emerge in four to six weeks.

Propagation through stem cuttings

Another method of Unona buchananii propagation is through stem cuttings. Here’s how to do it:

1. Select a mature, healthy stem from the parent plant with a length of about 10-15 cm.
2. Cut the stem at a 45-degree angle using a sharp, sterilized knife.
3. Remove the leaves from the bottom half of the stem.
4. Dip the cut end of the stem into rooting hormone powder.
5. Prepare a well-draining potting mix using loamy soil, sand, and organic matter.
6. Fill the pots with the prepared mix and plant the stem cutting about 5 cm deep into the soil.
7. Water the soil until it becomes moist and place the pot in a well-lit, partially shaded location.
8. Keep the soil moist by watering it regularly, but avoid overwatering as it may cause stem rot.
9. The stem cutting will develop roots in four to six weeks and can be transplanted into a bigger pot or directly to the garden bed.

Propagation through stem cuttings is a faster way to grow new plants and ensures that the offspring have the same characteristics as the parent plant.

Disease and Pest Management for Unona buchananii Engl.

Unona buchananii Engl. is a tropical plant native to Southeast Asia and is commonly known as Buchanan's Annona. Like all plants, it is prone to several diseases and pests that can damage its leaves, fruits, and stems. Proper disease and pest management can help maintain plant health and increase its yield.

Common Diseases

One of the most common diseases that affect Unona buchananii Engl. is anthracnose. It is a fungal disease that causes dry, dark, and sunken spots on the leaves and fruits. If not treated on time, the leaves will be damaged, and the fruit production will be affected.

Fusarium wilt is another fungal disease that can cause wilted leaves, brown or black discoloration on the stem, and stunted growth. This disease can quickly spread through soil or water, so preventive measures should be taken to avoid it.

Pest Management

Although Unona buchananii Engl. is relatively resilient to pests, it can still be attacked by several organisms that can cause damage. One of the most common pests that affect this plant is the fruit fly. It lays its eggs inside the fruit, making it unusable for consumption.

The mealybug is another pest that can cause harm to the leaves and flowers of the plant. These small, white insects suck sap from the plant, causing it to wither and die. It is recommended to remove any affected parts of the plant and apply insecticides to control their population.

Disease Management

To prevent fungal diseases in Unona buchananii Engl., it is necessary to maintain proper sanitation. Clean all tools or equipment when working on the plant to avoid contamination with fungi. If anthracnose infects the plant, remove all infected leaves and fruits and spray a fungicide to prevent further damage. The application of a systemic fungicide can also prevent infections from inside the plant.

Fusarium wilt can be controlled by keeping the plant clean and dry, avoiding overcrowding, and maintaining proper soil drainage. If affected by the disease, the plant should be removed immediately to avoid contamination with other plants.

Overall, a healthy plant is less susceptible to diseases and pests. Regularly monitor Unona buchananii Engl. for any signs of infestation or infection, and take necessary actions to control them. Following proper disease and pest management practices can help ensure a productive and thriving plant.