Narcissus and Daffodil

Production of Narcissus bulbs 69
can be used to bring up fresh soil and allow a shorter rotation. Where tulips are
grown in the same rotation, they should follow narcissus, since the tulip race of
stem nematode attacks narcissus bulbs but the narcissus race does not attack
tulips. Other hosts of the stem nematode, which should be avoided, include (1)
crops such as onion, maize, peas, beans, sugar beet, mangold, carrot, turnip, red
clover and strawberries, (2) bulbs such as bluebells and hyacinth, and (3) weeds
such as speedwell, scarlet pimpernel, chickweed, cleavers and black bindweed
(Jones and Jones, 1984). For the export of bulbs to certain countries, they must
be grown on soil certified free of potato cyst nematode (PCN): although PCN
does not attack narcissus, the cysts can be carried on soil attached to dry bulbs.
Spores of the base rot fungus are widespread, and have been found even in soils
not previously known to have grown narcissus (Price, 1975a,b). Base rot spores
may remain viable for up to 10 years, at least under artificial conditions (C.A.
Linfield, personal communication). Diagnostic methods for the base rot fungus
have been investigated (Linfield, 1993). Field populations of Fusarium oxysporum
f.sp. narcissi are being characterised using molecular tools with the ultimate goal
of developing sensitive and specific detection systems for this pathogen in bulbs
and soils. These in turn may lead to diagnostics capable of predicting the disease
potential of fields selected for narcissus production (J.H. Carder, personal
communication).
Bulbs left behind in the ground after harvesting (‘volunteers’ or ‘groundkeepers’)
are difficult to eliminate, but the removal of these bulbs is important in controlling
pests and diseases. Contact herbicides (such as paraquat or glyphosate),
cultivation and picking by hand should be used (Tompsett, 1974).
Economic factors
The site chosen for narcissus bulb production should take account of the local
availability of experienced labour, if required for labour-intensive operations such
as flower cropping or bulb cleaning. The location of markets, local infrastructure
and availability of logistics services should also be considered.
Pre-planting operations in the field
Cultivation
Whenever soil is compacted, or suspected of being so, it should be sub-soiled
(deep-ploughed) prior to growing narcissus. Good agricultural practices must be
used, for example, carrying out sub-soiling when the soil is dry enough to burst
the compacted layer but not wet enough to cause smearing. Perennial weeds
should be removed by cultivation or by using a translocated herbicide. The land
should be ploughed well in advance of planting, and when the soil is dry enough
for structure to be maintained. Either the whole field should be ploughed and
roadways taken out later, or permanent headlands should be established. After
ploughing, the land may need further cultivation, to 25 cm depth in clay or loam,
or 35 cm in sand. If the bulbs are not ready to plant and conditions are dry, the
prepared land may be rolled to conserve moisture. In appropriate soils, the use of
stone and clod separators before planting is becoming more usual. To avoid soil