INVESTIGATIONS ON THE NARCISSUS DISEASE. 55 
crops liable to infection, and in which eelworm can tide over until the 
ground is again occupied by bulbs. Whilst on a visit to Spalding last 
July, the susceptible crops in the district were examined for eelworm. 
In two instances onions, lucerne, and clover (all susceptible crops) were 
found growing in close proximity to diseased Narcissus bulbs, but it 
must be confessed no damage appeared to have been caused by eel- 
worm. One criticism I would reply to in advance. The cross-inocula- 
tion experiments at Wisley have been conducted under glass and many 
factors eliminated which come into play in the open air. However, it 
seems certain that the problem of rotation will have to be considered 
if a successful cure is to be found. 
An important question under consideration is to ascertain in 
what manner bulbs become affected, and a series of experiments, which 
are not yet completed, has been arranged. It appears from field 
observations that the disease commences in the neck of the bulb. The 
leaves at the surface and below the ground level become a decayed 
squashy mass, and, in consequence, they lose their elasticity and topple 
over in all directions. These leaves do not show the twisting character- 
istic of the diseased foliage from a diseased bulb. This decay in the 
neck is usually evident in late May and early June at a time when the 
foliage is withering, and the symptom is sometimes confounded with 
the natural decay of the leaves. Many growers are of the opinion that 
moist, dull, warm weather favours the spread of the disease at this 
stage, and such conditions possibly aid the development of eelworms 
and render them more active. Exactly how the eelworms gain an 
entrance has yet to be shown. It is generally believed that foliage 
injured by frost and other external agencies offers a ready means of 
access. This may be so, but the leaf-inoculation experiments prove 
that eelworm is capable of itself of gaining an entrance owing to its 
possession of a spearing apparatus — a needle-like structure present in 
its gullet. In the case of a healthy bulb planted in infected soil the 
hard, brittle outer scales would afford natural resistance to the entrance 
of the eelworm, and in preference it would attack the soft growing 
foliage. In any case, the eelworms usually attack the leaves at the 
neck, and this is a possible explanation of the decay of the foliage at 
this point. Once inside the leaves, the Tylenchus makes rapid down- 
ward progress to the basal plate, where it appears to find better condi- 
tions of growth. Here the eelworms propagate most freely, the basal 
plate splits away from the bulb, and often the eelworms are to be seen 
in masses resembling cotton wool hanging from the base (fig 29). At 
this stage the eelworms leave the bulb via the broken basal plate and 
enter the soil, attack other bulbs, and so spread the disease. The bulb- 
mite and fungi, possibly including Fusarium, then gain an entrance. 
In cases where flowers are picked (as in the case of the Daffodil 
flower industry, where many flowers are picked in the bud stage and 
opened indoors) the wound so left affords a ready means of entry for 
eelworm from the soil. In order to obtain a long flower-stem, they 
are picked as far into the neck as possible, sometimes below the 
