Annona Species Monograph.pdf - Crops for the Future

Chapter 10. Agronomy
Alvarez et al. (1999) pointed out that there are basically only two types of
pruning: for plant formation and for plant production.
Pruning for plant formation begins in the first year at the same time as the
training operation, though this may vary according to the species, and
continues until the fifth year after planting out (Agustín and Alviter, 1996). It
is necessary to begin training cherimoya trees in the nursery (Nakasone and
Paull, 1998), however, soursop and sugar apple produce their branches close
to the ground and have a single trunk (Coronel, 1994; Pinto and Ramos,
1997), therefore, they do not require interference at such an early stage.
Pruning has several objectives: a) development of good tree architecture in
order to increase yield; b) acceptable aeration and light penetration; c) ease of
access for cultural practices, such as artificial pollination, pesticide spraying
and harvesting; d) removal of lower limbs (especially those touching the
ground) and branches that are rubbing against each other (Torres and
Sánchez, 1992; Pinto and Ramos, 1997; Nakasone and Paull, 1998;
Bonaventure, 1999).
Anderson and Richardson (1992) described an additional pruning practice
that should be carried out during the first 4 years. This involves cutting the
single trunk at 80 cm height, to stimulate production of primary branches. In
the spring of the second year, the primary branches should be cut at a length
of 40 cm to stimulate production of secondary branches. Similarly, in the
third and fourth years, the same pruning procedures should be made to the
secondary and tertiary branches, however, with 30 cm and 20 cm lengths,
respectively (Fig. 10-9). It is important that care be taken during this
procedure to ensure that a large number of internal branches do not remain
and impede the necessary canopy aeration. Therefore, this type of pruning
should be supplemented by an annual pruning through which better aeration
of the internal canopy is maintained (Nakasone and Paull, 1998).
Agustín and Alviter (1996) described different pruning methodologies for
cherimoya involving the maintenance of two and three principle branches.
Pruning using the two-branch system should begin between the fourth and
the fifth month after transplanting. The two principal branches should be
selected according to their vigour, and the others should be removed
establishing a v-shaped training type (resembling two fingers in an opened
position). The three-branch system described by Nakasone and Paull (1998)
requires the complete removal of the top part of the tree leaving 90 cm of the
main trunk, this encourages the production of lateral branches. Agustín and
Alviter (1996) commented that these lateral branches should be at angles of
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