32 
BULLETIN 616, U. S. DEPARTMENT OF AGRICULTURE. 
in the different check plats shows the uncertainty of the infestation 
and the necessity, in order to obtain reliable comparison, of several 
interspersed lots of unsprayed trees. The comparisons would be still 
more accurate if it had been feasible to leave single untreated trees 
interspersed among the sprayed trees of each plat, but the work of 
keeping the fruit from a large number of scattered trees in 17 plats 
separate for examination would involve too much time and expense, 
and there would be much risk of the pickers, paid by the box, mixing 
the fruit. 
Table VII. — Comparison of fruit sprayed for the citrus thrips with that un- 
sprayed, Series I, Lindsay, Cal., 1911. 
No. 
of 
plat. 
Treatment of trees. 
Untreated 
Lime-sulphur (36° Baume), 1-28 , 
Lime-sulphur (36° Baume), 1-56 
Untreated 
Tobacco extract (40 per cent nicotine 
sulphate), 1-800 
Tobacco extract (40 per cent nicotine 
sulphate), 1-1,600 
Untreated 
Lime-sulphur (36° Baume), 1-86, and 
tobacco extract (40 per cent nicotine 
sulphate), 1-800 
Lime-sulphur (36° Baume), 1-86, and 
tobacco extract (40 per cent nicotine 
sulphate), 1-1,600 
Lime-sulphur (36° Baume), 1-86, and 
tobacco extract (40 per cent nicotine 
sulphate), 1-2,400 
Cresol soap, 1-500, and tobacco extract, 
1-1,600 
Cresol soap, 1-500, and tobacco extract 
(40 per cent nicotine sulphate), 
1—2,400 
Untreated 
Fish-oil soap, 1-250, and tobacco ex- 
tract (40 per cent nicotine sulphate), 
1-800 
Fish-oil soap, 1-250, and tobacco ex- 
tract (40 per cent nicotine sulphate), 
1-1,600 
Sulphur-soda, 1-25 
Sulphur-soda, 2-25 
Resin wash, 1-3 
Resin wash, 1-5 
Resin wash, 1-10 
Plain water 
Untreated 
Amount of fruit 
examined. 
Num- 
ber of 
loose 
boxes. 
20 
Num- 
ber of 
oranges, 
2,386 
2,308 
2,243 
2,180 
2,300 
2,281 
2,442 
2,337 
2,420 
2,387 
2,345 
2,126 
2,648 
2, 555 
2,444 
2,563 
2,622 
2,700 
2,760 
2,596 
2,639 
2,650 
Commercial grading of fruit. 
Number 
of first- 
grade 
oranges. 
1,981 
2,285 
2,225 
1,734 
2,247 
2,160 
2,188 
2,272 
2,321 
2,174 
2,071 
1,740 
1,878 
2,299 
2,041 
2,294 
2,510 
( x ) 
( 2 ) 
( 3 ) 
2,191 
2,176 
Number 
of second- 
grade 
oranges. 
405 
23 
18 
446 
53 
121 
254 
65 
99 
213 
274 
386 
770 
256 
403 
112 
448 
474 
Per cent 
first- 
grade 
oranges. 
83.1 
98.9 
99.1 
79.4 
97.5 
94.6 
89.5 
97.1 
95.8 
91 
88.2 
SI.! 
70.; 
0) 
( 2 ) 
( 3 ) 
82. 
82 
Per cent 
second- 
grade 
oranges. 
16.8 
1 
20.4 
2.3 
5.1 
10.4 
2.7 
18.1 
29 
16.4 
10.4 
4.1 
16.9 
17.8 
1 83.6 per cent of fruit injured by spray. 
2 69.6 per cent of fruit injured by spray. 
3 43.7 per cent of fruit injured by spray. 
The fruit from plats 1 and 4 was considered as one unsprayed lot 
for comparison with the sprayed fruit from plats 2 and 3 ; that from 
plats 4 and 7 as a check on the same from plats 5 and 6, etc., in 
order to get unsprayed fruit as nearly as possible representative of 
what sprayed fruit would have been without treatment. More than 
