Mature macadamia orchards can deliver higher yields, but without careful management, trees become costly and unproductive. At Barberton Valley Plantations in Mpumalanga, farm manager Denys Snyman focuses on pruning and root health across 807 hectares of orchards, some over 20 years old.
"The best time to start pruning macadamias is a year after planting," says Snyman. "This is when you start establishing the strategic frame of the tree by removing unnecessary branches. Branches that are not productive are just consuming fertiliser and water, but don't give anything in return."
Overgrown trees reduce sunlight and chemical penetration, lowering yield and quality. "Annual pruning is therefore not negotiable. If cash flow is an issue, then I'd rather cut back on fertiliser," he adds. Nuts grow on horizontal branches, and Snyman removes vertical and secondary leaders to stimulate productive growth. Branches are layered with 600mm gaps to ensure light distribution. Hedge trimmers are avoided, except for cultivar 741, which grows very tall and requires topping.
Older orchards are planted at 8m x 3.5m spacing (357 trees/ha) while newer plantings use 9m x 3m (370 trees/ha). The farm manages 14 cultivars, including 816, 741, Nelmac, A203, A268, and A4, with average yields of 3.5t/ha. Cultivar 741 yields up to 4.5t/ha with low kernel recovery, while 816 has higher recovery but requires intensive care.
Pruning has also reduced pesticide use. Application volumes have dropped from 3,000L/ha to 2,200L/ha due to improved canopy penetration. "Before we embarked on this pruning programme, we just couldn't reduce the macadamia nut borer numbers. Once the trees were opened up through pruning, the pesticides became far more effective," Snyman says.
Irrigation remains a critical factor, particularly during nut set and hot winds in late spring. Snyman applies about 400L/tree/week, rising to 500–600L/tree/week during nut set. Stress is induced by holding back irrigation before flowering, with watering resumed once nuts are setting.
Soil compaction management has prompted a shift from micro-sprinklers delivering 100L/hour to 45L/hour nozzles applied more frequently. This keeps the topsoil moist and supports the macadamia's shallow proteoid roots.
Harvesting has reverted from mechanisation to manual systems to reduce compaction and retain mulch. Staff are supported by hand-pushed mini harvesters and blowers to clear nut beds. Growth regulator ethephon is applied to manage nut drop in Beaumont and 816 cultivars, ensuring staggered harvests.
Snyman emphasises that yields depend on annual management. "Proper management from day one, and every year thereafter, will result in trees that are able to flourish, producing yields befitting of their age."
Source: Farmer's Weekly