 Planted bulbs are susceptible to nematodes, the most serious of which is Ditylenchus dipsaci (Narcissus eelworm), the main cause of basal plate disease in which the leaves turn yellow and become misshapen. Infested bulbs have to be destroyed; where infestation is heavy avoiding planting further narcissi for another five years. Other nematodes include Aphelenchoides subtenuis which penetrates the roots causing basal plate disease and Pratylenchus penetrans (lesion nematode) the main cause of root rot in narcissi. Other nematodes such as the longodorids (Longidorus spp. or needle nematodes and Xiphinema spp. or dagger nematodes) and the stubby-root nematodes or trichodorids (Paratrichodorus spp. and Trichodorus spp.) can also act as vectors of virus diseases, such as TBRV and TomRSV, in addition to causing stunting of the roots.
