1939] SERVICE AND REGULATORY ANNOUNCEMENTS 
61 
Temperature. — The temperature of the soil at a depth of 6 inches must be 
at least 45° F. when the treatment is applied, and must not fall below 40° 
during the period of the treatment. 
Dosage. — Two and one-half gallons of dilute emulsion to each square foot 
The concentration is dependent upon the temperature. Follow table 3 of 
paragraph (m) (1). 
Application. — Level the surface of the soil, removing weeds and debris. Force 
a galvanized-iron collar 3 inches into the ground, and firm the soil against the 
metal. Place another collar next to the first, and so on. When enough collars 
are in place, pour the dilute emulsion into the basins formed within the collars. 
As soon as the liquid has disappeared from the surface, the collar may be lifted 
and set in another position. 
Period of treatment. — The soil must not be disturbed for 48 hours. 
[9) NAPHTHALENE FUMIGATION 
Condition of soil. — The soil must be friable and in good tilth. 
Temperature. — The temperature of the soil at a depth of 6 inches must not 
be less than 50° F. during the period of the treatment. 
Dosage. — Forty-six pounds to 1,000 square feet, or 2,000 pounds per acre. 
Application. — The naphthalene must be thoroughly mixed and incorporated 
with the upper 3 inches of soil. 
Period of treatment. — The soil must not be disturbed for 1 week. 
Treatment of Soil About the Roots of Plants 
The effect of insecticidal treatments on plants, when applied to soil about their 
roots, varies with the variety, age, vigor, and condition of the plants. It should 
be understood that these treatments have not been tried on all varieties of 
plants, or under all of the varied conditions in the nurseries. In general, it is 
not possible to destroy an insect in close proximity to the roots without causing 
some damage to the plant. While guarantees cannot be given that no injury 
will be caused to the plants, the treatments are recommended only for those 
plants which experience has shown were not seriously injured. It must be 
understood by the nurseryman that no liability shall attach either to the United 
States Department of Agriculture or to any of its employees in event of injury. 
After all treatments the plants must be handled in such a manner as to prevent 
reinfestation. 
(0 Treatment of Plants After Digging 
( l ) removal of infestation 
With some deciduous and herbaceous plants, infestation can be removed by 
shaking and washing all soil from the roots. Only such root masses as can be 
thoroughly examined and absence of infestation verified may be certified by this 
procedure. 
(2) HOT- WATER TREATMENT 
Equipment. — A water tank, equipped with a suitable heating device and 
circulating system, must be provided. 
Temperature. — The water must be maintained at 112° F., with a variation of 
not more than ± 0.5°. Before the plants are immersed, thermometers must be 
inserted in the center of at least three of the largest clumps, baskets, or root 
masses placed at each end and at the center of the tank. In addition, three 
thermometers must be placed in the water of the tank in the same relative 
positions as those in the root masses. Temperature readings from each of these 
thermometers must be recorded on Form No. 91. 
Application. — The root masses must be immersed completely. 
Period of treatment. — Seventy minutes after the root masses are heated to 
112° F. 
Varieties of plants— The varieties which have been treated successfully by 
this procedure are given in Technical Bulletin 274. 
Preparation of plants. — Large clumps should be divided as much as possible 
without injuring the roots. Excess soil should be removed and the roots pruned. 
Small plants and rootstocks may be packed loosely in wire baskets or in other 
