Narcissus and Daffodil

Production of Narcissus bulbs 95
Figure 4.9 Letter box drying wall for bulbs in bulk bins. Air is blown through the slots
in the wall into the pallet bases of the one tonne bins which are stacked
against them (Photograph: Horticulture Research International).
unpublished data). While single treatments with thiabendazole can be highly
effective, it is the cumulative effect of treatment over several years that most effectively
reduces incidence of the disease, and if base rot is severe fungicide can be
applied both post-lifting and in HWT (Hanks, 1992b, 1996b).
Bulb drying
Rapid and efficient bulb drying is essential for good bulb quality and especially for
controlling base rot, since the pathogen does not spread effectively under dry conditions
(Hawker, 1935, 1940). The method of bulb drying depends on the scale of
the bulb-growing operation and on the temperature regime adopted for drying.
On small farms, bulbs may be handled in small containers (e.g., bulb trays), in
which case they may simply be stacked in a well ventilated or open shed, or even
outdoors, allowing sufficient air spaces between stacks of containers; alternatively,
to avoid problems due to unsuitable weather and to speed drying, the trays may
be dried under ceiling fans in a shed or controlled temperature store. Loose bulbs
can be elevated onto the floor of a bulk store fitted with air ducts for drying as
used for grain or onions. Bulbs in bulk bins require a special drying facility, a
‘letter box’ drying wall (Figure 4.9). The bins have solid sides and a slatted pallet
base, of which the fork-lift slots form the air duct for drying and ventilating bulbs
via the slatted base of the bin. The bins are placed against slots in the drying wall
located at appropriate positions to match the pallet bases of the bins, building up a
line of bins of length and height appropriate to the facility, and closing the pallet
bases at the outer ends of the rows with a temporary closer, usually a thick piece of
foam rubber, so that the air flow from the letter boxes is forced upwards through