80 CALIFORNIA CITRUS CULTURE. 
Distance over tree. 
8 J2022/2426728 fo [32 [3 
- f 
16 
{18 
20 
22 
‘|g 24 
ito Frozro: Sane & “426 | 
a ae T eee 28- 
3 rovalrarereg 
19 20/2024 0 
Tals lisiie fiGi07 ish 2a 2 
13 F415 [16 [1778 (6, ilazile 4% 
4 [5 ite (17 [7/08 i920 é 
(6 16:17 [tal9 F2o'2r| 
| 
ites es 
(40142|44/46|48950 152 
1718 [192020 122 
21 22/23 
a2 922/23 24)25 25.926 
125125 26926272 
425/262 
Distance around tree. 
[re aie Ze ets} 36 36)38)39)41 59 
Fic. 54.—Schedule No. 1. The first few dosages should be doubled. 
(U. 8S. Dept. Agrel.) 
LENGTH OF EXPOSURE. 
The time required to complete the generation of the gas is not long, 
but it is advisable to leave the tents upon the trees for at least forty-five 
minutes after the dosage is placed under the tent. Some prefer thirty 
minutes, while others insist upon a full hour. 
TIME OF OPERATION. 
For red, purple and yellow scale fumigation work is usually done 
during the winter or spring months. If black scale is present the time 
of operation covers the period from the middle of August to the middle 
of January, depending somewhat upon the individual locality. 
TEMPERATURE. 
To avoid the heat of the sun, fumigation is ordinarily done during the 
night, when the atmosphere is cool. Cloudy cool days may admit of 
