Annona Species Monograph.pdf - Crops for the Future

Chapter 10. Agronomy
Torres and Sánchez (1992) describe two types of pruning for soursop tree
formation, both called 'free canopy shapes': a) pruning to keep a central axis
with horizontal lateral branches (Fig. 10-10 A); b) pruning to keep forked
branches (Fig. 10-10 B). Branch formation should begin between 60 and 80
cm above the soil, and plant height must be kept to 3.5 m (Fig. 10-10).
Figure 10-10. Two types of pruning for soursop tree formation: A) by
keeping a central axis and horizontal lateral branches; B) by keeping
forked branches. Adapted from Torres and Sanchéz (1992)
During the pruning for soursop tree formation it is important to break the
apical dominance of branches, in order to promote the growth of new lateral
branches; this is followed by another pruning to leave 3 to 4 well distributed
new branches, with insertion angles of approx. 30° in relation to the trunk
(Torres and Sánchez, 1992). Soursop trees naturally produce a symmetrical
canopy well adapted to a central-leader system; therefore, a good alternative
for soursop tree formation is to develop a mushroom-shaped tree that is
topped at a height of 2.0-2.6 m (Nakasone and Paull, 1998). When the
soursop tree is properly trained, little pruning is required, except to thin out
poorly placed and weak branches, as well as the annual pruning of the
longest branches extending horizontally and vertically (Nakasone and Paull,
1998).
Torres and Sánchez (1992) described pruning for the maintenance and
rejuvenation of soursop. Pruning for maintenance is required two to three
times a year, preferably after harvesting. It consists of the elimination of
undesirable branches, i.e. those which are not productive, dried twigs and
dead branches, or those which are diseased; it also includes the elimination of
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