Pruning mature and encroached avocado trees to restimulate and maintain production and fruit quality

Many avocado plantings in South Africa are reaching the stage where a decision has to be made to either remove the orchard, thin out rows, or retain the trees by pruning them into a shape and size that is more manageable and will produce a commercial yield of good quality fruit. The Institute for Tropical and Subtropical Crops, together with producers, has been researching these problems over the past five years in various growing areas. Several strategies have been put forward and tested during this time. As a result of this research, more than one pruning option is available to the producer, ranging from light hand pruning to heavy mechanical pruning. Cost implications for these systems have to be taken into account to ensure the most economically beneficial result. Selective hand pruning can easily be applied in orchards where the encroached stage is not yet evident. Trained labour can carry out these operations. Yield does not drop dramatically in these situations and good fruit size and quality is maintained after pruning. Re-growth after the pruning operation is minimal and can be effectively controlled. In seriously encroached situations, a more drastic approach will be necessary and chain saws or other mechanical equipment are required to get the iob done effectively. Regular removal of unwanted, upright watershoots also needs to be carried out. In higher potential soils growth regulators must be incorporated in the tree management programme to assist the producer in regrowth control. It is also important to follow the correct nutritional programme (especially nitrogen) to manage growth. An encroached orchard in the Kiepersol area was recently pruned after harvest using different pruning techniques for encroached orchards. This orchard will serve as demonstration to help producers in their decision-making about cost implications, time of recuperation, growth reaction, follow-up operations and so on. This paper will discuss these options, with the aim of providing growers with the information they require to maintain productive, well managed orchards.