1932 J 
SERVICE AND REGULATORY ANNOUNCEMENTS 75 
HOT-WATER TREATMENT FOR EELWORMS 
Permits not to be issued, even after treatment, for bulbs from heavily infested 
plantings or blocks. — As outlined on a later page and in instructions numbered 
B. P. Q.-338, the grower is under obligation to prevent the building up of a 
general infestation on his premises. When a large proportion of the bulbs, such 
as one-tenth to one-fifth or more, are found to be eelworm-infested, the nemas 
become so numerous in and around the planting and in and on the bulbs that a 
single treatment can not be expected to eradicate the infestation completely. 
Under these conditions it is also especially difficult to protect the treated bulbs 
from reinfestation on the premises. In such cases, permits are not to be issued 
for interstate movement even after applying the hot-water treatment. The 
bulbs may be treated and replanted and the whole situation worked out with 
the grower as described under the section on "Field sanitation" (page 76); 
Federal permits wall then be withheld until some future season after the grower 
has reduced the infestation to such a point that treatment can be expected to be 
effective in eliminating any remaining eelworms from the shipping stock. 
Process.- — Subject to the provisions of the previous paragraph, if an eelworm 
infestation either with or without narcissus bulb flies was disclosed during either 
field or warehouse inspection or if the inspector has been unable to determine to 
his full satisfaction that the narcissus are free from eelworms, the bulbs con- 
cerned are to be immersed in hot w r ater maintained at a temperature of not less 
than 110° F. and not more than 111.5° for not less than three hours computed 
from the time the water regains the loss of temperature occasioned when the 
bulbs are submerged. In the case of bulbs over 2 inches in diameter, four (in 
place of three) hours are required. 
Construction of treating vat. — Various forms and shapes of vats are used. Heat 
may be obtained either by the injection of warm water or steam or by the use 
of a hot-water or a steam coil or electric unit in the tank. The use of vats in 
which it is necessary to apply direct outside heat from a torch or other open 
fire is not authorized. 
The best results are obtained in the use of the hot-water treatment when the 
water in the tank is circulating continuously throughout the entire period of the 
treatment. In the case of rectangular tanks this is brought about by the use 
of a propeller at one end of the tank under a false floor above which the bulbs 
are placed. The false floor is of a slatted or skeleton type and baffles are used 
to force the water to circulate among the bulbs. The bulbs must be so arranged 
in baskets or crates in some manner, such as separation and staggering, so that 
adequate circulation is possible. If it is necessary to use sacks for small amounts, 
open mesh bags such as onion sacks are employed and the w r ater temperature 
in the center of the sack must reach 110° F. before the treatment is considered to 
have started. 
The temperature is to be tested by means of a standardized testing thermometer 
or a thermometer which has been checked against a standardized thermometer. 
In testing the adequacy of the treating tank at the beginning of the season it is 
desirable to use a long vat thermometer by means of which the temperature at 
the bottom as w T ell as at the top of the tank can be obtained. There should not 
be more than 0.5° F. difference between one part of the tank and another. 
To avoid injuring the bulbs and to be sure of killing the nematodes, the bulbs 
should preferably be treated not less than 14 days after digging and not more 
than three w r eeks. If the bulbs have dried for a greater length of time, they 
should be soaked for 12 hours in cold water before being treated. This soaking 
is in order to break the dormancy of the eelworms in the dry scales. Any water 
thus used must be disinfected before being used again or being thrown out on 
farm soil. This can be done by heating it to 140° F. for 12 minutes. 
Bulbs are not to be crammed into treatment tanks to full capacity, as this 
prevents circulation and interferes with the maintenance of uniform temperature. 
Narrow baskets are preferable to crates or sacks. The top bulbs, like the others, 
are to be covered with water. Any floating bulbs, scales, etc., are to be removed 
and destroyed with the culls. 
To avoid any possibility of disseminating infections of basal rot or other 
diseases, it is necessary, first, to cull out any soft, rotten, or infested bulbs before 
treatment; and, second, to disinfect the bulbs with a fungicide during or after 
treatment. If ceresan disinfectant is used, the cold or lukewarm solution after 
completion of the hot-water treatment is preferable to its use in the hot wrater. 
Methods of such disinfection are given in Circular P. Q. C. A. — 324. 
Bulbs should be cooled rapidly after treatment, and, unless immediately planted, 
should be dried promptly and thoroughly. 
