32 PLANT QUARANTINE AND CONTROL ADMINISTRATION [April-June 
Table 4. — Dosage for square collars 
Length of side of collar 
Water 
Miscible carbon disulphide for tem- 
perature of— 
40°-50° F. 
50°-60° F. 
60°-70° F. 
Inches 
12 . 
Gallons 
2.5 
4.0 
5.5 
7.5 
10.0 
12.5 
15.5 
19.0 
22.5 
26.0 
30.5 
35.0 
40.0 
Cubic cen- 
timeters 
17 
27 
37 
51 
68 
85 
106 
129 
153 
177 
208 
238 
272 
Cubic cen- 
timeters 
14 
23 
31 
43 
57 
71 
88 
108 
128 
148 
173 
199 
227 
Cubic cen- 
timeters 
11 
15 
18 
18. 
25 
21 
34 
24 
45 
27 
57 
30 
70 
33. 
86 
36... 
102 
39 - - 
118 
42... 
139 
45 
159 
48„ 
182 
Temperature of the soil. — Begin treating in the spring when the minimum 
soil temperature at a depth of 6 inches remains above 40° F., using 68 c c of 
miscible carbon disulphide to 10 gallons of water. When the minimum soil 
temperature at this depth remains above 50°, decrease the concentration to 
57 c c to 10 gallons. When the minimum soil temperature remains above 60°, 
decrease the concentration to 45 c c to 10 gallons. In the autumn, as the mini- 
mum temperature of the soil decreases, it is necessary to increase the con- 
centration in the opposite order. Treatment must be discontinued when the 
minimum soil temperature at the 6-inch depth is below 40°. 
For the treatment to be successful the temperature of the soil during the 
48-hour period of treatment should never fall below the minimum temperature 
for the dosage being used, as shown in Tables 3 and 4. A map has been pre- 
pared of the different townships of the northern and middle Atlantic seaboard 
States, based upon data from the United States Weather Bureau, which indi- 
cates the probable dates when the soil temperature at a depth of 6 inches will 
not fall below 40° F. The inspector should obtain from the treating division 
headquarters information on this point with respect to the area in which he is 
working. The dates for the minimum temperature are shown in Table 5. 
Treatment may be started on the date given in the first column, and the dosage 
should be changed accordingly. 
Table 5. — Minimum temperature dates 
Spring temperature 
Autumn temperature 
Zone No. 
40° F. 
50° F. 
60° F. 
60° F. 
50° F. 
40° F. 
1 
Mar. 4 
Mar. 11 
Mar. 19 
Mar. 27 
Apr. 4 
Apr. 11 
Apr. 19 
Apr. 27 
May 4 
May 11 
Apr. 19 
...do..-- 
Apr. 27 
...do.... 
May 4 
May 11 
May 19 
-..do 
May 27 
June 4 
May 19 
...do.... 
May 27 
...do 
June 4 
June 11 
June 27 
...do.... 
July 11 
July 19 
Oct. 11 
...do.... 
Oct. 4 
...do.__. 
Sept. 27 
...do 
Nov. 4 
...do.... 
Oct. 27 
...do.... 
Oct. 19 
...do.— 
Dec. 11 
2 
Do. 
3 
Nov. 27 
4 . 
Do. 
5 • 
Nov. 19 
g 
Do. 
7 
Sept. 19 
Sept. 11 
Aug. 27 
Aug. 19 
Oct. 11 
Oct. 4 
Sept. 27 
...do 
Nov. 11 
8 
Nov. 4 
9 
Oct. 27 
10 
Do. 
The inspector must keep an accurate record of the minimum soil tempera- 
tures at a depth of 6 inches throughout the season. An accurate thermometer 
graduated in at least single degrees must be used. The temperatures must be 
taken between 6 a. m. and 8 a. m. each morning in order to obtain the minimum 
temperature. This must be done in the nursery plots or beds from which the 
plants are being taken. If the soil temperature in the spring has not reached 
