Agriculture Reference
In-Depth Information
When less-compact canopies are desired, pinching can be done every
second or third fl ush, and later the canopies are opened at the centre by
removing interior branches, so that the plant and fruit receive more light.
In some tropical areas topping of the vegetative shoots at the second or
fi rst internode is done to obtain more-compact trees (Galán Saúco, 2009).
Pruning can also be done to accommodate the trees for espaliers and trellises,
where pinching is done at the height of the fi rst wire so that two new shoots
are directed along the wire and the third shoot grows up to the second wire,
and repeated.
After the trees have been adequately trained, annual pruning is not
usually practised. Mango trees normally make very dense growth, and
occasionally light thinning of branches will become necessary to facilitate
light penetration, air movement, pesticide penetration, removal of dead and
diseased branches and some control over tree height. The tallest branches
are cut back at the fork (point of origin) of the branch. 'Water sprouts' and
overlapping branches may be removed annually. In Florida, pruning is done
with machines called 'ledgers' and 'toppers' by cutting back the height and
width of the trees to about 4 m. This is done annually immediately after
harvest (Campbell, 1988). These trees have two or three vegetative fl ushes
before becoming dormant at the onset of winter and then produce fl owers in
the following spring.
Pruning becomes a major endeavour when trees are allowed to outgrow
the space provided. Yields are reduced and harvesting becomes dii cult
and uneconomical. Removal of alternate trees appears only to aggravate
management problems later, as remaining trees will grow even larger. Drastic
pruning of large trees to about 2 m to develop new tops on old trunks may
cause approximately 3 years' loss of income. Yearly pruning to less than ~3 m
to control tree height is practised in Taiwan, without signifi cant impact on
year-to-year production. The fruits are bagged to reduce disease and insect
damage, and fruits thinned to match fruit load to tree size (Fig. 10.8).
In cultivars with biennial (irregular) fl owering, shoots that have fl owered
are removed after harvest, leaving only shoots that may fl ower next time.
Flowering shoots that do not set fruit should also be removed soon after
fl owering. Removal of apical buds after each fl ushing cycle to increase the
number of terminal shoots that could fl ower can lead to better fruiting and
limits tree size (Oosthuyse and Jacobs, 1995). The number of terminal shoots,
however, is not always related to the number of fruit set (Fig. 10.9). There is
a strong correlation between number of terminal shoots and fruit number
for the cv. 'Sensation', which retains a higher number of fruit per shoot than
'Kent', indicating that other factors are involved. Deblossoming of the terminal
infl orescences can lead to infl orescence development from axillary buds, a
20-30-day-later harvest and higher yields (Chang and Lion, 1987).
In the lower tropics, where fl owering time is modifi ed, synchronization
pruning is done every year to force the trees to produce new shoots at the
