32 MISC. PUB. 526, U. S. DEPT. OF AGRICULTURE 
In preparing this spray, add the sulfonated castor oil to the water. 
Next add a small quantity of this oil-and-water mixture to the derris 
or cube powder to rake a uniform paste. Then stir the paste slowly 
into the remainder of the oil-and-water mixture. Finally add the 
pyrethrum extract to this mixture in case it is intended for the control 
of thrips or the cyclamen mite. For either red spiders or whiteflies, the 
pyrethrum may be omitted. A proprietary spreader-sticker, such as 
sodium oleyl sulfate plus synthetic resinous base, may be substituted for 
the sulfonated castor oil in the above formula, since the oil may at 
times injure the petals of open flowers and also the foliage of some 
plants. ‘This material is used at the rate of 34 teaspoonful per gallon, 
or 11% pints per 100 gallons, of spray mixture. 
For the control of the Kuropean corn borer on market or home-garden 
sweet corn a spray is preferable to a dust. In mixing the spray, 4 
pounds of the ground root (containing not less than 4 percent of 
rotenone) are used per 100 gallons of water, plus a suitable spread- 
ing agent, either sodium monosulfonate of butylphenylphenol or aro- 
matic monosodium sulfonate. Rotenone-bearing powders containing 
the proper quantity of suitable spreading agent may sometimes be 
found on the market. The spreading agent facilitates the penetration 
of the spray deep into the whorl and between the leaf sheaths and the 
stalk where the larvae feed. Thorough wetting of these areas is nec- 
essary to insure reaching the young borers. As there is danger of in- 
juring corn by using too much spreader, the quantity of this should be 
carefully regulated. To prepare the spreading agent for mixing with 
a spray, dissolve 1 pound of the spreader in 2 quarts of water and then 
add enough water to make 3 quarts (96 ounces) of solution. This 
makes a stock solution of the spreader sufficient for 300 gallons of 
spray. 
: Ne of commercial preparations containing extracts of derris 
or cube, with various spreaders added, are now available and are ready 
for dilution with water. 
Derris or cube extracts should be kept in closed containers, and 
sprays should be applied immediately after their preparation. These 
sprays lose their effectiveness within a comparatively short time after 
they are applied to plants. 
Properly packaged and stored ground roots containing rotenone 
do not deteriorate appreciably for several years, nor does any detert- 
oration occur when they are diluted with inert carriers like pyrophyl- 
lite, neutral talc, or powdered plant products and placed in closed 
containers in a dark, dry room. 
Caution.—Ground rotenone-bearing roots irritate the tender 
skin and the mucous membranes: 
SOAP SPRAYS 
Sprays made from soap are very useful, especially for small plant- 
ings or house plants. Dissolve a cubic inch of ordinary soap or 2 table- 
spoonfuls of soap flakes in 1 quart of water. If fish-oil soap is at hand, 
a rounded tablespoonful may be used. Soap sprays are useful against 
