Macadamia, native to Australia, is where this tree originates from. It has the potential to grow as tall as 20 meters. Grafted varieties typically require 3-4 years from the time of planting to begin producing nuts, whereas local varieties typically take 6-7 years to reach the same stage.
Suitable Ecological Conditions
Macadamia trees thrive in tropical regions, making them flourish in areas that receive ample sunlight but are protected from strong winds, which is crucial for optimal fruit production. They require deep, well-drained soil that is slightly acidic to moderately acidic, with a pH level ranging from 5 to 6.5. The ideal annual rainfall for macadamia trees is between 800 and 1200mm. Furthermore, they prefer temperatures within the range of 16 to 25 degrees Celsius.
Proper irrigation plays a vital role in the initial two years of macadamia seedling development. To enhance water retention, a basin with a diameter of 60cm is constructed. During this early stage, the seedling necessitates 20 liters of water every two weeks. As the tree matures, the frequency of irrigation is gradually decreased.
The southern green stink bug cannot sustain itself solely on macadamia nuts; it relies on a primary food plant for survival. It is essential to remove host plants where the stink bugs reproduce and develop before they feed on macadamia trees. In order to manage weeds between the nut trees, non-selective herbicides such as CATAPULT can be utilized.
To eliminate troublesome weeds like black jack, a mixture of AGROMINE and CATAPULT can be employed.
Mulching is a practice that is performed regularly to retain moisture, preserve nutrients, and inhibit the growth of weeds.
Pruning is beneficial for maintaining the tree’s overall structure and enhancing yields. It is typically conducted prior to flowering and after the completion of harvesting. To prevent the spread of diseases, it is recommended to disinfect pruning shears using BIOSURE. During the pruning process, damaged wood is removed to minimize nutrient competition within the tree.
Leaf and soil sampling are conducted to assess the fertilizer needs of the crop. The following fertilizers can be used to meet the specific requirements:
- FERRARI GOLD: This fertilizer provides the necessary calcium and other essential microelements needed by the plant.
- VITABOR GOLD: It contains added nitrogen, which aids in the plant’s uptake of boron.
- ZINC GOLD: Chelated zinc is included in this fertilizer to supply the plant with the maximum amount of zinc it requires.
- GOLDCHANCE SUPER START, GROWTH, and FLOWER&FRUIT: These fertilizers are designed to provide the macro-elements required in varying ratios during different stages of growth.
- LAVENDER TOTAL: This fertilizer ensures an adequate supply of nitrogen (N), phosphorus (P), potassium (K), and trace elements throughout the plant’s growth cycle.
Pests and Diseases
Termites are frequently observed on the trunks of young trees, particularly during dry periods. Particular care is taken to eradicate the queen ants, and a drench of RANGER can be administered within the basin of young trees to address this issue.
If not effectively addressed in a timely manner, macadamia farmers are experiencing nearly a 50% loss in their expected production due to damages caused by the stink bug. The prevalent species found in nut trees is the southern green stink bug, scientifically known as Nezara viridula. This insect possesses piercing-sucking mouthparts in the form of a long beak-like structure called a rostrum. The life cycle of the stink bug spans around 65 to 70 days, and the females have the ability to lay up to 260 eggs, which are typically deposited on the undersides of leaves.
Stink bugs have a preference for feeding on mature nuts that still have green husks. The damage caused by these insects is typically observed during the post-harvesting and processing stages. Stink bugs use their stylet-like mouthparts to place them on the husk of the nut, secreting saliva that contains digestive enzymes. This saliva softens the husk, allowing the stink bug to penetrate it and reach the kernel. As a result, discolored pits can be found on the surface of the kernel, and immature drops may occur. Furthermore, the infected kernel provides an entry point for molds and fungi, leading to additional losses and a decline in the desired quality of the harvested nuts.
To maintain control over stink bugs, it is important to regularly monitor the plants and initiate treatment when the action level is reached. The action level is typically considered when 4% or more of the sampled green fallen nuts are found to be infested.
Routine pesticide application is advised to decrease the population of stink bugs. It is recommended to use systemic and contact pesticides for effective results. Some recommended products include LEXUS, KINGCODE ELITE, and DOBERMAN.
Macadamia nut borer
The larvae of the cryptophlebia ombrodelta pose the greatest threat as they are the most destructive stage. The eggs of this pest are deposited on the surface of the green husk. Once hatched, the larvae tunnel into the husk while it is still soft and proceed to feed on the kernel. This feeding activity results in hollow, dimple-like marks on the shell, which can provide entry points for molds, further compromising the quality of the nuts. Infestations also lead to premature nut drop, reducing overall production.
- Remove old infested nuts from the orchard floor to minimize the population of pests.
- Implement the use of pesticides such as Pentagon, Kingcode elite, and Occasion star to effectively control the pests at the early stages of nut development.
Mealybugs tend to gather on the nut stalk, where they feed and excrete a sticky substance called honeydew. This honeydew serves as a substrate for the growth of sooty mold, which diminishes the photosynthetic surface area on leaves. As a result, the affected leaves gradually turn yellow and wilt. The female mealybug has an oval shape and can lay up to 600 eggs that resemble cotton balls.
Furthermore, adult mealybugs are covered with a white or gray waxy substance that gives them a mealy appearance. They have a preference for shaded areas such as crevices of stems or the undersides of leaves, making it challenging for insecticides to effectively penetrate and control them. Consequently, their control becomes more difficult due to their sheltered locations.
- Outbreaks of mealybugs are sporadic, and they are often kept in check by natural predators, particularly the mealybug ladybug (Cryptolaemus montrouzieri), which usually offers sufficient control.
- To address the issue of sooty mold and honeydew, Jamboclean can be used. This product helps in clearing away the mold and sticky residue while also removing the protective outer waxy layer of the mealybugs. This dehydration leads to their demise and enables easier penetration of pesticides.
- Consider using Constantine as a pesticide to effectively control and manage mealybug populations.
There are two common types of scales that affect macadamia trees: the white scale (Pseudaulacaspis brimblecombei) and the latania scale (Heniberlesia lataniae). These scales create small raised spots on the nuts, appearing white to greyish in color. If left untreated, scale infestations can spread to leaves and branches, causing damage. Scales typically measure up to 2mm in diameter.
To control these scale infestations, it is recommended to use a mixture of Doberman or Lexus combined with Jamboclean. This combination of pesticides helps eradicate the scales effectively.
Thrips cause damage to macadamia nuts by feeding on the outer husk, resulting in a brown or bronze discoloration. However, the impact on yields and quality is typically minimal. Adult thrips are small insects measuring around 1.5mm in length. In cases of high infestation, thrips may affect the leaves and flowers of the macadamia tree.
To control thrips, it is advisable to spray the affected trees with pesticides such as Presento, Kingcode elite, or Doberman. Since thrip damage is often sporadic, targeting the affected areas with these pesticides can help manage the infestation effectively.
The moths responsible for infesting macadamia trees lay their eggs on the flower panicles. Once hatched, the larvae feed on the florets for approximately three weeks before entering the pupal stage. If an infestation occurs during the flowering stage, it can result in reduced production unless detected and controlled in a timely manner.
To control these moths, it is advised to regularly inspect the flowers for any signs of silken matting or the presence of larvae. Using a pesticide such as OCCASION STAR, pay special attention to the folded leaves where the larvae tend to hide. This targeted approach can help effectively manage and control the infestation.
Husk spot disease
The cause of this condition is the fungus Pseudocercospora macadamiae. Symptoms of the disease include the presence of pale yellow flecks on the husks, which gradually enlarge to form darker yellow to dark brown circular spots. This fungal infection thrives in moist conditions, and the affected spots often produce gray, velvety fungal spores. Infected nuts tend to drop prematurely, up to six weeks earlier than expected.
To control this disease, it is advisable to use a preventative spray of Biodistinction Extra in areas prone to the infection. This proactive approach can help reduce the incidence and impact of the disease on macadamia trees.
Root rot is a fungal disease caused by Phytophthora cinnamomi, commonly occurring in areas with excessive moisture and poor drainage. This condition leads to the abrupt death of affected plants.
To control root rot, it is recommended to administer a drench of CHANCETYL ELITE on the affected plants. This treatment can help manage the fungal infection and mitigate the impact of root rot on macadamia trees.
This is a severe infection that can impact various parts of the macadamia tree, including the stem, leaves, fruits, branches, twigs, and bark, often resulting in wilting and even death of the plants.
To control the spread of this infection, it is crucial to maintain proper hygiene practices when handling affected plants. This includes taking measures to prevent the transmission of the disease from one plant to another. By implementing and maintaining good hygiene protocols, the spread of the infection can be effectively stopped and further damage to macadamia trees can be minimized.
Premature nut drop
Green nut drop in macadamia trees can be attributed to various factors such as natural thinning, damage from fruit spotting bugs or nut borers, husk spot disease, heat stress, storm damage, or tree decline. This condition is often characterized by a significant number of green nuts dropping from the tree. Natural nut drop typically occurs between 3 to 8 weeks and 10 to 30 weeks after flowering. To identify the cause, fallen green nuts are monitored and examined through sectioning.
To manage green nut drop, it is important to implement good pest and disease management practices, ensuring proper crop nutrition and irrigation. Additionally, the use of OPTIMIZER, a natural blend of seaweed and micro-elements, can help reduce plant stress caused by excessive heat, thereby reducing nut drop and enhancing crop yield.
Macadamia nuts are ready for harvesting once the skin starts to crack. In their unripe state, the husk of macadamia nuts appears white, but as they ripen, it typically changes to a chocolate brown color. Harvesting the nuts is relatively simple as they tend to drop off the trees when they reach maturity. It is recommended to maintain a clear area underneath the trees to facilitate the easy collection of all the nuts.