Agriculture Reference
In-Depth Information
leave a short cane. This pruning will force new vigorous growth. Cof ee plants
are cut back to 30-40 cm and they will start to regenerate their canopies, and
in this way they will be rejuvenated and return to a more manageable size and
be more productive. Regeneration pruning can also be done in old and large
trees of several species where size has reached unmanageable proportions and
there is a need to reduce it.
Pruning to change a variety
A grower can change the variety of an orchard that is mature but still healthy
and vigorous. The mature trees are pruned to leave the bases of the three or
four scaf old branches (Fig. 4.4). Scions or bud-wood can be grafted on to
the stubs of the scaf old branches directly or on to the shoots coming from
them. This operation reduces the time for the orchard to come back into full
production, as compared to starting with new plants from the nursery.
When large scaf old branches are cut back and left without shade from
the canopy, care has to be taken to avoid sunburn. Normally the whole trunk
and the remaining portions of the scaf old branches are protected with
whitewash prepared at the farm or with white latex paint. The wounds have
to be disinfected and protected; in some cases aluminum foil is used to cover
them. An alternative to this could be to cut one or two of the branches and
graft them, while the others are left intact and will provide protection and keep
the normal sap fl ow within the plant; the next year the remaining part of the
plant will be cut back and grafted (Razeto, 1993).
Pruning cuts and tools
Pruning cuts, if smaller than 1 cm in diameter, are normally not treated, but
larger cuts are treated with a paste containing copper, such as copper sulfate
or other fungicide, and sometimes insecticide, to avoid the entrance of some
pathogens or insects. Under very wet situations and if certain diseases are
present, almost any cut has to be disinfected; sometimes it is best is to wait for
a dry spell to prune.
Pruning tools include pruning shears, pruning saws, chainsaws and
even machetes. Machetes are not recommended, but they are used to prune
trees that have a soft wood. Tools should be disinfected before pruning the
next tree, in order to avoid transmission of diseases from one tree to another.
In some cases, such as with fi re blight, tools should be disinfected between
each cut (Harris, 1983). Disinfection is of the utmost importance with some
tree species or when disease is present, to protect the rest of the grove from
becoming infected. In banana plantations, the machetes used for eliminating
suckers are disinfected after each cut is made, to avoid the spread of 'Moko',
