1920] SERVICE AND REGULATORY ANNOUNCEMENTS 67 
conditions of the soil are important. The solution must not d sappear from the 
surface in less than 10 minutes, and must be absorbed by the soil within 5 
hours. 
Temperature. — The temperature of the soil 6 inches below the surface must 
be at least 45° F. when the treatment is applied. If the temperature falls be- 
low 40° F. before the treatment is finished, the soil must be treated again. 
Season. — Treatment must not be applied when adult beetles are present. An 
exception may be made in the case of plots that are protected from beetles. 
Dosage. — Miscible carbon disnlphide must be used at the rate of 97 cubic 
centimeters, diluted in 10 gallons of water. Two and a half gallons of the 
dilute emulsion must be applied to each square foot of soil 
Application. — Level the surface of the ground, removing weeds and debris. 
Force a galvanized-iron collar 3 inches into the soil, 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 carbon disnlphide 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 after 
treatment. 
C. 4. Treatment with naphthalene 
Material. — Flake naphthalene. Caution. Fire should be kept away from 
naphthalene. 
Equipment. — The equipment used in mixing fertilizer with soil can be used 
for naphthalene, providing the chemical is first mixed with about ten times its 
volume of dry soil. 
Condition of soil. — Any type of soil may be treated with naphthalene provid- 
ing it is friable. It must not be wet or soggy. The success of the treatment 
depends, to a large extent, upon the condition of the soil. 
Season. — The treatment must not be applied when adult beetles are present. 
Temperature. — To be effective the temperature of the soil at a depth of G 
inches must not be less than ~,0° F. for a week after treatment. 
Dosage. — Naphthalene must be used at the rate of 1.000 pounds per acre, or 
23 pounds per 1.000 square feet. 
Application. — Plow and harrow the soil until it is in good tilth. Mix naph- 
thalene with 10 times its volume of dry soil, broadcast over the surface, and 
harrow in to a depth of 4 inches. Cross harrow several times, until the naph- 
thalene is intimately%mixed with the soil. 
Period of treatment— -The land must not be disturbed for one week after 
treatment. 
3. DISINFECTION OK SOIL ABOUT THE ROOTS OF PLANTS 
The following methods have been found satisfactory for disinfecting soil 
about the roots of plants. For lists of plants to which the various methods 
of treatment may be applied see pages 72 Tti. 
.1. Removing infestation by Washing with Water 
Washing ;.n soil from the roots of the plants with water is probably one of 
the most Simple methods for removing the infestation from certain Varieties 
of plains. The method has certain disadvantages in that it is dependent for its 
effectiveness almost entirely upon the vigilance and the determination of the 
inspector in making sure that all soil is washed from the roots and that no 
tangled mass of roots i r cavity hides a larva. 
Condition of plants. Plants in a dormant or semidormant condition are 
usually most resistant to the action of water on their roots. Actively grow- 
ing plants may be seriouslj injured, it is therefore recommended that the 
treatment be applied when the plants are in a dormant condition. 
Application of treatment. The Large clumps must be divided and the roots 
pruned to reduce the size of the plant as much as possible. All soil must be 
washed Crom the roots. Then with knife and wire examine all cavities and 
Crevices In the roots to make certain that no larvae are I 
e of plants aft<r treatment.— Precautions must !.•• taken after treatment 
to prevent reinfestation. if the plants are to be potted, set th m in disin- 
fected soil as see,, as possible, if they are to be placed in storage or shipped 
'"' method oi handling will depend upon the variety. Bulbs and tubers should 
be dried thoroughly before packing, it is often beneficial to "puddle" the 
roots oi deciduous Stock after washing all the SOi] from the roots 
