COMBINED SPRAYS FOR CONTROLLING INSECT PESTS. 
(9) and (10) Ammonium Polysulphide with Soap, with or without 
Nicotine. 
The preparation of effective spraying materials is an out- 
standing example of the success of the scientist. Bordeaux mix- 
ture was one of the earliest sprays developed in Europe for the 
control of grape diseases. Lime sulphur solution was the outcome 
of American work, especially for summer spraying om stone fruits. 
Now we have a valuable preparation as a result of work by Pro- 
fessor Salmon and Dr. Eyre, at Wye College, England, in their 
investigation on the control of the American Gooseberry Mildew 
now widespread throughout Europe. It has this advantage over 
lime sulphur—it does not leave any deposit on berries, &c., sprayed 
with it; hence it can be used at any stage without the fruit being 
marked. Powdery mildews have, as a rule, been treated with 
powder sulphur, and various mixtures of sulphur and other sub- 
stances. American Gooseberry Mildew, however, in the powdery 
stage, is readily attacked by ammonium polysulphide solutions and 
soap, which is much superior to liver of sulphur (Pot. sulphide). 
Owing to the difficulty and danger in making ammonium poly- 
sulphide, it must be bought ready prepared in the concentrated form 
like lime sulphur solution, but smelling strongly of ammonia. It 
is an orange-red liquid, very pungent, but, when diluted, is harmless 
and non-poisonous. It should always be used with soap, and insecti- 
cides, such as nicotine, or quassia extract, can be added. Once 
prepared for spraying, it should be used and not allowed to stand 
for any length of time. Wooden and iron vessels are to be used, 
and the spraying machine well washed after use. It contains 18 
per cent. of ammonia and 22 per cent. of combined sulphur, 
chiefly as the polysulphide 13 per cent., and the sulphide 9 per 
cent. : 
In a combined spray 1 gallon is diluted with 100 gallons of 
water, and there should be at least 4 lbs. of free soap present. The 
soap is boiled in the water required, and the ammonium polysul- 
phide liquid is added and stirred well. When applied under proper 
conditions it not only stops the growth of the fungus and the spread 
of disease, but in many cases destroys the mycelium. The active 
ingredient is the ammonium polysulphide, and it is very useful 
against all kinds of mildew—rose, peach, apple, and gooseberry— 
and other fungi. It will be noticed that soap is not recommended 
with lead arsenate, lime sulphur, or Bordeaux. The difficulty of 
using soap with hard water and salt water is probably known to 
most people. The curd that floats to the surface is an insoluble 
hard soap, formed by the lime or salt in such waters decomposing 
the soap used and forming a new compound with part of it. Soap 
is a compound of the caustic soda (or lye) and the acid part. of 
the fats used.. With hard water the curd will continue to form, 
until all the substances in solution, causing the hardness, have been 
combined with the acid part of the soap, replacing the soda part. 
Any soap in excess of the quantity required to do this 1s known 
as free soap, and will be then available to make a lather, or to act 
as a film spreader. If soap were used with sprays containing lead, 
lime, or copper, each of these would produce an insoluble curd or 
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