76 BUKEAU OF PLANT QUARANTINE [July-Sept. 
FIELD SANITATION 
The suppression of local infestations of bulb pests is less directly within the 
field of the United States Department of Agriculture than within that of the 
State in which the bulbs are grown. In order to eradicate or control eelworm 
infestation to the extent necessary to secure Federal permits, however, certain 
precautions are necessary to avoid building up infestation on the premises. 
This section of the present instructions is devoted to that phase of the problem. 
The first step in field sanitation is to determine exactly what the field condi- 
tions are. Repeated reinspections may be necessary for this purpose. Such 
inspections can be continued by experienced employees of the grower after the 
State or Federal inspector has completed his work. In the case of a general — 
even though slight—distribution of infestation throughout the planting, it is 
necessary to consider the entire area as infested. 
If roguing of a limited number of isolated spots of infestation is attempted, 
all plants within at least 18 inches of any infested plant should be carefully 
destroyed, being sure that infested soil is not distributed in the field during the 
operations. Culls and rogued plants may be destroyed by placing them in a pit, 
covering with oil, and burying under 18 inches of soil. The soil around the 
spaces or areas from which infested plants have been removed may then be dis- 
infected by saturation with kerosene (1 pint to the square foot). An alternative 
plan which has some advantages consists of leaving the infested and neighboring 
plants in the field and saturating them and the surrounding soil with kerosene. 
It should be noted that this paragraph on roguing relates only to field sanitation. 
The remainder of the bulbs in the block should be treated even though roguing 
has been carried out. The certification without treatment of bulbs taken 
from blocks from which eelworm-infested plants have been rogued is no longer 
authorized. 
Any animals, clothing, tools, or machinery which come in contact with the 
soil of an eelworm-infested area should be disinfected either with formaldehyde 
or kerosene. Machine cultivation in infested blocks is likely to result in spread 
of the infestation down the row. This can be avoided in part by the substitution 
of hand cultivation where necessary. 
The bulbs from all eelworm-infested blocks and plantings should be dug and 
treated each season, and the planting stock from the plot concerned retreated 
every year until at least one and preferably two years after infestation has appar- 
ently been eliminated. This digging and treatment practice is needed not only 
for the commercial crop which is shipped the same year but also for other narcissus 
on the premises, such as stock for intrastate movement, replanting, and narcissus 
which has been imported under special permit and not yet released. 
Narcissus should never be planted on eelworm-infested soil. Freeing soil from 
eelworms after it has once become infested is difficult and not fully satisfactory. 
The usual plan is that of employing a 4-year rotation under which no eelworm 
host plants are grown during the three years between narcissus crops. During 
these years, plants immune to Tylenchus dipsaci should be chosen if practicable. 
In any event, avoid bulbous, leguminous, biennial, and perennial crops. It is 
also necessary to keep the field free from weeds as certain wild plants are subject 
to attack. It is essential that volunteers and rogues which have been missed in 
digging the crop be carefully removed the first season, as otherwise these volunteer 
narcissus will carry the infestation through. 
In special cases soil may also be disinfected with steam or with kerosene as 
indicated on a previous page. In employing kerosene for disinfection the dele- 
terious effect of oil on the future fertility of the soil must be considered. This 
material is adapted for use only on limited spots of infestation. Experiments are 
progressing in which other less expensive chemicals are being used on a Targe 
scale, but the results are not yet conclusive. 
In some sections the soil used in and around greenhouses has become eelworm- 
infested and it is necessary for State inspectors to make provision for the eradica- 
tion of infestation in and around such greenhouses in order to avoid contamina- 
tion of commercial plantings in the same vicinity. It is important that this 
suppressive work should be carried out carefully, even though the greenhouses 
concerned may never wish to ship narcissus bulbs. 
Lee A. Strong, 
Chief, Bureau of Plant Quarantine. 
