Narcissus and Daffodil

Production of Narcissus bulbs 101
promote more ‘sympathetic’ production protocols. This might also apply to plants
being grown for processing for the production of pharmaceuticals, where it may
be desirable to exclude pesticides for various reasons. As well as environmental
reasons for encouraging less reliance on pesticides, there is the practical situation
that relatively few pesticides are approved for use on horticultural crops: sales of
pesticides, other than for use on major crops, are unlikely to justify the development
and registration costs, and the chemical armoury of the grower of horticultural
crops has decreased in recent years and may decrease further. In the
Netherlands, the major bulb-growing country, the intensity of horticultural
production, high use of pesticides and fertilisers to reduce losses due to pests and
diseases and to increase yields, and the vulnerability of the water table and water
courses have led to major restrictions on the use of agrochemicals in the bulbs
industry. Raven and Stokkers (1992) and Stokkers (1992) summarised this situation,
reporting that 10% of the use of pesticides in the Netherlands was used in
the production of flower-bulbs (a 12-fold higher input than the average input per
ha), and listed the objectives of the Dutch ‘Multi-year Crop Protection Plan’
(Anon., 1990). There is a need to develop integrated crop management (ICM) for
narcissus crops. The setting up of experimental farms to test prototype ICM systems
for bulbs was described by Raven and Stokkers (1992) and De Vroomen and
Stokkers (1997). De Ruijter and Jansma (1994) described a model which optimizes
production as regards environmental goals (nitrogen residues and pesticide inputs)
and financial goals (income) for crops including narcissus, while Rossing et al.
(1997) explored the options for environmentally friendly flower-bulb production
systems and the prospects for pest and disease control in bulb crops in a world less
dependent on agrochemicals was reviewed by Van Aartrijk (1997). A recent review
of three systems for growing narcissus in the Netherlands – integrated, experimental
integrated and biological – suggested there were good prospects for the
integrated system (Wondergem et al., 1999).
Up to now, little research has been conducted specifically on more environmentally
friendly narcissus bulb production, although several possibilities are evident
from previous R&D (Hanks, 1995b). These include physical, cultural and biological
methods. Thus, in handling narcissus bulbs, emphasis has been laid on rapid
drying and correct storage to reduce the levels of base rot (Hanks, 1992b, 1996b).
Cultural methods of base rot control would include early lifting and late planting
to avoid high summer soil temperatures, and there is also scope for using mulches
or controlled weed growth to reduce soil temperatures, conserve water and
reduce the reliance on herbicides. Koster et al. (1997) reported trials on the development
of low-dose herbicide treatments for bulbs, involving leaving straw
mulches in place to prevent weed germination, covering the soil with intercrops
between bulb crops, and optimising the use of mechanical weed control, which
might involve changes to bulb planting systems. In trials to control the nematode
Pratylenchus penetrans, flooding was an effective alternative to soil sterilisation (van
Beers, 1990). On a small scale, solar sterilisation may be useful (Higgins, 1999).
The biological control of the base rot pathogen by antagonistic fungi has been
reported by Langerak (1977), Beale and Pitt (1990, 1995), Hiltunen et al. (1995)
and Hanks and Linfield (1997). Non-pathogenic micro-organisms (Penicillium
species, Trichoderma species, Minimedusa polyspora and a Streptomyces species) inhibited
pathogen growth, reduced disease development, or improved the effects of