REFLECTIONS ON DISEASE TREATMENT 183 
4 gallon “ A.P.S. 1919” is diluted to 100 gallons by the 
addition of water. Saponin at the rate of 2 ounces per 
100 gallons of spray should be added, and two sprayings 
are necessary at a week’s interval. Solutions of colloidal 
sulphur are now on the market and should prove valuable 
aids in the combating of plant disease, but at present 
little can be said about them. 
Spreaders 
It is a matter of some difficulty to wet thoroughly 
the foliage of some plants if only aqueous solutions 
are being used. In order to overcome this difficulty 
“* spreaders,” which increase the wetting power of the 
spray solution, are added. 
The first known spreading agent to be used was soft 
soap, but this has now been replaced by other and more 
suitable compounds. Of these saponin, calcium caseinate, 
flour paste, and certain resin mixtures are the most 
important. Saponin at the rate of 2 ounces per 100 
gallons may be added to most fungicides with beneficial 
results. In the case of Bordeaux and Burgundy Mixtures 
it increases the wetting power and helps to keep the 
precipitates in suspension for a longer time than would 
otherwise be possible. 
Certain plants, such as the cucumber and carnation, 
are only imperfectly wetted, even with the addition of 
saponin, but this may be overcome by using flour paste, 
which imparts an efficient wetting power to the solution. 
In the Lea Valley it was first used with “ liver of sulphur ” 
and ‘lime sulphur” as a means of combating the 
Colletotrichum leaf spot of the cucumber, for which the 
following sprays are recommended : 
Liver of Sulphur and Flour Paste— 
5 Ib. flour. 
4 1b. potassium sulphide (liver of sulphur). 
100 gallons water. 
Smaller quantities may be made up at a time by taking 
