EXPERIMENTS FOE CONTROL. 
21 
spider could be easily controlled; that sulphur dusted or blown onto 
the vines would soon check their progress. General observations 
made in the infested fields that were thoroughly dusted with finely 
powdered sulphur, however, lead the writer to believe that dry 
sulphur is of no value whatever in checking the ravages of this mite 
upon hops. This point was most conclusively proved, as will be seen 
from the following data. 
In testing the efficiency of this material upon the mites, all the 
available forms of dry sulphur were purchased and a precipitated form 
was prepared by treating a lime-sulphur solution with hydrochloric 
acid. These sulphurs were applied in the form of dust (PI. Ill, fig. 2) 
and also with water as a "wet spray." Table No. Ill gives results 
which were obtained from tag counts taken at various times during 
the season of 1911 and 1912. 
Table III. — Negative results produced by sulphur in various forms used against the 
red spider on hops. 
Date. 
1911. 
June 30 
July 15 
18 
18 
25 
1912. 
July 10 
Material. 
Precipitated sulphur, 10 pounds; 
flour paste, 4 pounds; water, 100 
gallons 
Flowers of sulphur, 20 pounds; 
water, 100 gallons 
Precipitated sulphur, 10 pounds; 
water, 100 gallons 
do 
Precipitated sulphur dust, applied 
dry 
Precipitated sulphur dust. 
Num- 
ber of 
mites 
present 
before. 
271 
201 
264 
305 
560 
638 
Num- 
ber of 
mites 
killed 
by ap- 
plica- 
tion. 
146 
163 
Per 
cent of 
mites 
killed 
by ap- 
plica- 
tion. 
55.3 
53.4 
Days 
be- 
tween 
appli- 
cation 
and 
third 
count. 
0) 
Num- 
ber of 
mites, 
third 
count. 
In- 
crease 
of mites, 
282 
1,458 
1,533 
C 1 ) 
670 
1,198 
11 
1,257 
1,269 
C 1 ) 
560 
Per 
cent of 
in- 
crease. 
4.06 
625.00 
480. 68 
19.64 
87.77 
1 Tags lost after second count. 
Mites of all ages (larvae, nymphs, and adults) were observed from time to time on the tagged leaves. 
This table definitely illustrates the inefficiency of sulphur in con- 
trolling the red spider on hops. It will be noted that a certain 
percentage of mites was killed or washed off by the spray, but the 
increase which followed proves definitely that sulphur in the dry 
form has little or no effect upon the mites. Observations in fields 
where sulphur had been applied by hand and by a traction dust 
machine also bore out this statement. In some cases there were 
few mites upon the sulphured vines, and growers claimed that the 
sulphur had destroyed the mites. Near-by unsulphured foliage, 
however, was invariably found to be as free from mites as the " sul- 
phured" vines, and this assumption did not hold. 
Sulphur as a control of the red spider on hops has been tested and 
found wanting and is superseded by the contact insecticides. 
