Narcissus and Daffodil

Disposable yield (t/ha)
40
30
20
10
0
20 25 30 35 15 20 25 30
Planting density (t/ha)
First 1-year cycle Second 1-year cycle 2-year cycle
Production of Narcissus bulbs 81
Figure 4.5 Narcissus bulb yields for one- and two-year-down growing (data from
ADAS, 1993).
if poor growth occurs in one of the two years of the growing cycle, for example
due to early senescence or pesticide damage. Two-year-down growing has enabled
UK narcissus growers to become very efficient by reducing the annual demand for
labor, land, storage and other resources (ADAS, 1986b). In some cases, growers
may leave narcissus crops down for a third year for economic reasons, perhaps
because bulb prices are low or the flower crop is more important, but this is not
a practice that is recommended as good husbandry. Other reports of trials
comparing one- and two-year-down growing have been reported from Denmark
(Rasmussen, 1976a) and Poland (Sochacki and Mynett, 1996), confirming the
advantages of the two-year-down system.
The main disadvantage of two-year-down growing is that HWT and other
useful procedures (such as post-lifting fungicide treatment or high-temperature
drying) can be carried out only in alternate years, so there is no opportunity every
year to control stem nematode and other harmful organisms. Fungal pathogens in
the soil and stem nematodes in bulbs can build to serious levels over a two-year
period, while foliar fungal diseases (such as smoulder) are serious problems only
in the second-year of narcissus crops. In the summer between the two growth
periods, bulbs remain in the soil when temperatures are high and liable to encourage
bulb rots, and the benefits of early bulb lifting (the avoidance of narcissus fly
and aphid-borne virus infection late in the growing season) are lost. When
narcissus are left in the ground, they begin growing earlier, and earlier rooting
may allow more effective infection by soil-borne pathogens while soil temperatures
are still high. Second-year narcissus shoot earlier, and may therefore be more
damaged by frosts. Where base rot is a major problem, a temporary return to oneyear-down
growing should be considered (Tompsett, 1984).
When growing narcissus for processing, rather than as ornamentals, different
considerations may apply. If high yields and the avoidance of pests and diseases are
important, one-year-down growing may be more appropriate. Where the most economical
growing system is required, two-year-down growing will be appropriate,
but there is unlikely to be any advantage of growing cycles longer than two years.