An overview of plum training systems in South Africa

Japanese plums are generally grown in South Africa for export to markets in Europe and the East. Only cultivars with long storage potential are grown to accommodate the 3-4 week shipping time required to reach these markets. Most orchards are grown in regions with inadequate winter chilling, necessitating the use of rest-breaking agents. Strong winds are typically experienced during the fruit growth period, and most orchards are consequently trellised to prevent the formation of rub marks that reduce the fruit value. Most modern plantings are planted at high densities with spacings similar to 4 x 1.5 m (1667 trees/ha) in hedgerow systems. Sometimes V systems are planted at 4 x 0.75 m (3333 trees/ha). Only vigorous Marianna and peach x almond hybrid rootstocks are used locally, primarily due to the poor soil conditions. In these vigorous high-density plantings, it is critical to enhance precocious fruiting to maintain tree size. To ensure storage potential and high fruit quality, light is aggressively managed. The details of these training systems are discussed and yield data presented. Due to the diversity in growth habit between plum varieties, different architectural habits are accommodated and managed separately within these training systems. This is particularly true for the maintenance pruning strategies discussed.