Overview of Macadamia tetraphylla L. Johnson
Macadamia tetraphylla L. Johnson, commonly known as the rough-shelled macadamia, is a tree species belonging to the family of Proteaceae. It is native to the eastern coast of Australia, particularly in the regions of southeastern Queensland and northeastern New South Wales. The plant is widely recognized for its economic and ecological importance, as it is the primary source of the delicious and nutritious macadamia nuts consumed globally.
Description & General Appearance
The Macadamia tetraphylla L. Johnson is a medium-sized evergreen tree that typically grows to a height of about 10–15 meters, with a broad and dense canopy. The leaves of this tree are alternate, leathery, dark green, and slightly curled at the edges, measuring 12 to 30 cm in length and are arranged tetrahedrally, hence its name tetraphylla. The rough-shelled macadamia produces small, creamy-white flowers, which then give rise to woody fruits with woody-husked shells enclosing the edible kernel - the macadamia nut. The fruits mature in late autumn and early winter, ready for harvest.
Common Names
Macadamia tetraphylla L. Johnson has several common names, including the rough-shelled macadamia, bush nut, maroochi nut, bauple nut, Queensland nut, and unwashed nut. These names originate from different regions in Australia, where the plant is endemic and has cultural and historical significance.
Uses
The Macadamia tetraphylla L. Johnson has various uses, with the macadamia nuts being the most popular. Macadamia nuts are highly nutritious and contain fatty acids that promote healthy cholesterol levels in the body. The nuts are consumed as snacks, and their unique flavor also makes them an excellent ingredient in desserts, such as cookies, cakes, and ice creams. Other uses of the tree include ornamental purposes, as its dense canopy and wide-spreading branches, provide excellent shade and landscaping value in gardens and parks.
Light Requirements
Macadamia tetraphylla requires high light intensity for optimum growth and production. The plant grows best under full sunlight exposure but can also thrive under partial shade. A minimum of 6 hours of direct sunlight is recommended for optimum growth and yield.
Temperature Requirements
The ideal temperature range for the growth and development of Macadamia tetraphylla is between 20°C and 28°C. Temperatures below 10°C and above 38°C can negatively impact the growth rate and development of the plant. Low temperatures can also cause damage to the leaves and young shoots.
Soil Requirements
Macadamia tetraphylla prefers well-draining soils that are moderately fertile and have good aeration. The tree can grow in a range of soil types, including sandy loam, loamy sand, and clay loam soils, with a pH range of 5.0 to 7.5. Soil with a high water-holding capacity or those that are poorly drained can cause root rot and other diseases. Additionally, the presence of excessive salt in the soil can also be detrimental to the growth of the plant.
Cultivation Methods for Macadamia tetraphylla L. Johnson
Macadamia tetraphylla L. Johnson is a tree species native to southeastern Queensland. It is also found in the northern part of New South Wales in Australia. To cultivate Macadamia tetraphylla, you need to consider the right location, soil requirements, planting, and maintenance practices.
Location
The plant thrives well in a location with full sun exposure and well-drained soil. The site should be away from strong winds, as this can damage the trees and affect yield. The plant needs enough space to grow and develop.
Soil Requirements
The ideal soil for Macadamia tetraphylla is sandy loam with a pH range of 5.5 to 6.5. The soil should be deep and fertile to provide sufficient nutrients to the plant. If the soil is too acidic, it is essential to add lime to improve the pH. Adding organic matter such as compost to the soil helps improve soil fertility and structure.
Planting
To plant Macadamia tetraphylla, you need to dig a hole with a depth of around 60 centimeters and width of 60 centimeters. It is essential to remove any stones, weeds, and grass within the area. Place the macadamia tree in the hole, fill it with soil, and water it adequately. Leave enough space for the tree to grow. It is advisable to plant the tree during the rainy season.
Watering Needs for Macadamia tetraphylla L. Johnson
Water is a critical requirement for the growth and development of Macadamia tetraphylla trees. Watering needs depend on the age of the tree, the soil type, and the time of the year. Younger plants require more water than mature trees.
Watering Schedule
The frequency of watering the plant depends on the soil moisture content, but it is advisable to water the trees every week during dry periods. It is important to avoid overwatering as this can lead to root rot and other diseases.
Irrigation Method
The most efficient method of irrigation is the drip irrigation system. It aids in conserving water and ensures that the water is distributed evenly. It is important to avoid wetting the leaves and foliar parts as this can cause fungal infections that affect plant growth.
Fertilization for Macadamia tetraphylla L. Johnson
Fertilization is crucial to ensure the trees have adequate nutrients required for growth and development. Macadamia tetraphylla has a high nutrient requirement, and the appropriate fertilizer should contain significant amounts of nitrogen, phosphorus, and potassium.
Fertilizer Application
The fertilizer should be applied in three split doses during the growing season. Apply the first dose when the new growth appears, the second dose during the mid-growing season, and the final dose towards the end of the season. Spread the fertilizer evenly on a concentric ring around the tree, about 15 centimeters away from the trunk of the tree.
Fertilizer Recommendations
Organic fertilizer is the best option for macadamia trees, and it is essential to use compost or manure. Conventional chemical fertilizers can cause damage to the trees if not applied appropriately.
Pruning Macadamia tetraphylla L. Johnson
Pruning is essential for macadamia trees to remove the damaged or diseased branches, improve fruit quality, and promote new growth. The best time to prune the trees is during winter or early spring when the tree is dormant.
Procedure
Remove the growth below the graft union and any new growth that emanates from the lower trunk. Prune to an outward-facing bud, ensure the cuts are clean and smooth. Remove any crossing branches and branches that interfere with the tree's form. Cut off the branches that look diseased or damaged. Regular pruning helps maintain the tree's shape and form and ensures maximum light availability for all parts of the tree.
Propagation methods of Macadamia tetraphylla L. Johnson
Macadamia tetraphylla L. Johnson, commonly known as the rough-shelled macadamia, can be propagated through different methods, including:
Seed propagation
Seeds are the most common way to propagate M. tetraphylla. It's important to use fresh seeds since they have higher germination rates. Once the seeds are obtained, they should be soaked in water for 24 to 48 hours before planting. After the soak, the seeds can be planted in containers filled with a well-draining potting mix. They should be covered lightly with soil and kept moist until germination occurs.
Cutting propagation
M. tetraphylla can also be propagated through stem cuttings. The best time to take cuttings is in late spring or early summer. Cuttings should be taken from healthy plants and kept in a cool, moist place until you're ready to plant them. To improve rooting, some people like to dip the cuttings in rooting hormone before planting them in a well-draining potting mix. Cuttings should be kept moist and out of direct sunlight until they develop roots.
Grafting propagation
Grafting is another way to propagate M. tetraphylla. It involves attaching a scion (a small branch with buds) of the desired variety onto a compatible rootstock. Grafting is typically done in late winter or early spring, just before new growth appears. Both the scion and rootstock need to be healthy, and there needs to be a good match between the two for grafting to be successful.
Overall, propogation of M. tetraphylla can be done through a variety of methods depending on the needs of the grower. With proper care and attention, each propagation method can lead to a healthy and successful macadamia tree.
Disease and Pest Management for Macadamia Tetraphylla L. Johnson
Macadamia tetraphylla L. Johnson, commonly known as the rough-shelled macadamia, is a tree crop that requires special care and attention to thrive. One of the vital management practices is controlling disease and pest infestations. Here are some common diseases and pests that affect Macadamia tetraphylla L. Johnson and how to manage them.
Common Diseases
Some of the most common diseases that affect macadamia trees include Phytophthora root rot, Armillaria root rot, and Botrytis blight.
Phytophthora root rot is characterized by yellowing and wilting of leaves, which eventually fall off, leading to the death of the tree. A fungus called Phytophthora cinnamomi causes this disease, and it thrives in wet soils. To manage this disease, ensure that the soil remains well-drained and avoid over-irrigation. Fungicides can also help control Phytophthora root rot.
Armillaria root rot, also known as shoestring root rot, is caused by the fungus Armillaria mellea. It causes the roots to rot, leading to stunted growth and yellowing of leaves. The most effective way to manage this disease is by removing and destroying infected parts of the tree.
Botrytis blight is caused by the fungus Botrytis cinerea, and it causes shoot blight, blossom blight, and nut rot. Infected tissue appears brown and necrotic, and a grayish mold may develop. To control this disease, maintain good orchard hygiene, prune infected parts, and apply fungicides.
Common Pests
Some pests that commonly infest macadamia trees include nut borers, macadamia felted coccid, and stink bugs.
Nut borers are the larvae of moths that bore into nuts, causing a reduction in yield. Use pheromone traps to monitor populations and apply pesticides when necessary.
Macadamia felted coccid is a sucking insect that secretes honeydew, leading to the sooty mold development and eventual defoliation. Prune and dispose of infected plant parts, and use insecticides to manage infestations.
Stink bugs feed on developing nuts, causing shell deformation and, in severe cases, rotting. Use pheromone traps to monitor populations, and timing insecticide applications to target adults before they lay eggs.
Effective pest and disease management practices are essential to maintain healthy and productive macadamia trees. Timely and appropriate actions can help prevent the loss of yield and improve the overall quality of the crop.
