Agriculture Reference
In-Depth Information
CULTURAL PRACTICES
Propagation and nursery management
Sexual
Seeds are only used in breeding programmes. Many of the important
commercial cultivars are female-sterile.
Asexual
Suckers with their basal corm or entire corms are used as planting material.
A sucker is a lateral shoot that has a basal corm and a short pseudostem that
arises at the base of a plant from the mother corm. Suckers are normally used
by small farmers or when few plants are needed. The dii culty with suckers
is their size, which makes handling and transportation dii cult. In addition,
disinfection, which is essential to avoid transporting insects, disease and
nematodes, is often inef ective. A young sucker just emerging from the soil or
a large sucker with narrow leaves and a large corm are normally planted with
the remaining roots at the same depth as they were originally, and the excess
leaves will be pruned back.
The banana exporting companies normally use corms that are at the
base of a plant that has not fl owered and that was raised in special nursery
fi elds; these corms will have a weight of 2.5-5 kg. In other cases, 1.6-1.8 m
tall sword suckers that have a diameter of 15-20 cm at 20 cm from the soil
are used. The suckers are dug out and 15-20 cm of the pseudostem retained.
Sometimes large, older corms (bull heads) from plants that have fl owered can
be used for planting if propagation material is scarce. Smaller pieces of corms
can also be used.
The ideal is to disinfect the corms. The corm is pared so no dark spots and
roots are left, and the pared corm is dipped in a mix of a fungicide, nematicide
and insecticide for 5-20 min. The large exporting companies use a hot water
dip at 56-58°C for 15-20 min or 65°C for 12-15 min. If no pesticides
are available or are not allowed, simply paring the corms is helpful to limit
transfer. Corms to be used for planting should never be left overnight on the
ground, they should be either covered tightly or put on a trailer or truck, to
avoid reinfestation by banana weevil.
When propagating material is scarce, several techniques can be used to
increase the number of suckers. A sucker is planted and, before it dif erentiates
a fl ower bud, several practices can be used to prevent further growth of the
apex and induce axillary bud growth. One practice is to drive a stake into the
pseudostem at a 45° angle, aiming to destroy the apical meristem, or a coring
tool is used to achieve the same objective. Another technique is to partially cut
the pseudostem before fl owering at about 1.5 m from the ground, so the top
will bend and it will look like a '7', or to cut it down; in other cases the outer
 
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