THE RED SPIDER ON COTTON. 63 
field, to plow up all the affected portion in order to save the balance 
of the field. The stalks should be piled up quickly and burned 
_with the assistance of straw or light trash. Such a severe measure, 
however, should be resorted to only in extreme cases, and the planter 
concerned must be the judge of its advisability. 
Since we have established by experimentation that red spiders are 
unable to liberate themselves when buried 1 inch or more in soil, 
the importance of plowing affected areas thoroughly is evident. 
INSECTICIDES. 
In the course of experiments with red-spider sprays 74 different 
spray combinations have been tested. 
Taste XXVII.—ZList of red-spider sprays employed with favorable results, Batesburg, 
Ser 
1. Potassium sulphid. 6. A water-soluble oil. 
2. Kerosene emulsion. 7. Resin wash. 
3. Lime sulphur (home-made). 8. Nicotine sulphate and miscible oil. 
4. Lime sulphur (manufactured). 9. Nicotine sulphate and fish-oil soap. 
5. A miscible oil. 10. Fish-oil soap solution. 
In addition to these successful sprays, special mention should be 
made of potassium permanganate. In a 2 per cent solution this is 
an excellent spray, but its cost is prohibitive, except in cases where 
only a few plants are to be treated. 
SULPHUR PREPARATIONS. 
Finely resublimed sulphur, both unadulterated and mixed with 
dehydrated lime, was thoroughly tested on infested violets, dahlias, 
roses, and cotton. It was applied with a dust gun during very warm 
weather. Heavy infestation on prostrate violets was eradicated 
by the sulphur dust; 60 per cent of the red spiders on dahlias were 
killed; 25 per cent of those on roses were destroyed; and from 1 to 
15 per cent mortality occurred on 4-foot cotton. Suspecting that 
this variation in mortality came about through the agency of surface 
radiation, the following test was made: A small area of ground sur- 
face was thoroughly dusted with resublimed sulphur, and a heavily 
infested potted violet plant was set into the center of this area, so 
that no leaves touched the ground. The foliage, which had not 
been treated, was about 6 inches from the soil surface. Examina- 
tion after 8 hours’ exposure on a very hot day showed that over 
99 per cent of the mites had been killed. When elevated a distance 
of 18 inches above the sulphured ground practically no mortality 
occurred to infested violets. This indicates that the heat radiated 
from the ground (acting on the sulphur immediately at hand) is the 
chief factor which determines the mortality resulting from the use 
e 
