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Pomona College Journal of Economic Botany 



Prof. Rolfs makes this statement regarding Bordeaux : 

 "The loss from spotting of lemons may be greatly reduced, if not entirely 

 prevented, by spraying with fungicides, such as potassium sulphid, ammonical 

 solution of copper carbonate, and Bordeaux Mixture." — Bull. 52, U. S. Dept. 

 Agrcl., p. 17, 1904. 



Among other sprays recommended by Dr. Woods and tried out by Mr. 

 Culbertson was the Self-boiled Lime-Sulphur Mixture of the following formula: 



The self-boiled lime-sulphur mixture is a combination of lime and sulphur 

 boiled with only the heat of slacking lime and is primarily intended for 

 summer spraying as a substitute for Bordeaux Mixture where the latter 

 is injurious to foliage or fruit. For most purposes Bordeaux Mixture is 

 the better fungicide, and should be used except when likely to injure the plants 

 treated * * * The self-boiled lime-sulphur mixture, however, when pre- 

 pared as a mechanical mixture with lime and sulphur with only a small 

 percentage of the sulphur in solution, is not injurious to peach foliage, and 

 in our experiments for two years past has proved to be a good fungicide. 



The mixture can best be prepared in rather large quantities — say 20 

 pounds, or even 40 pounds, at a time — so as to get enough heat to produce 

 a violent boiling for a few minutes. Place the lime in a barrel and pour 

 on enough water (about 3 gallons to 20 pounds) to start it slacking and to keep 

 the sulphur off the bottom of the barrel. Then add the sulphur, which 

 should first be worked through a sieve to break up the lumps, and finally 

 enough water to slack the lime into a paste. Considerable stirring is neces- 

 sary to prevent caking at the bottom. After the violent boiling which accom- 

 panies the slacking of the lime is over, the mixture should be diluted ready 

 for spraying, or at least cold water added to stop the cooking. Five to 

 fifteen minutes are required for the process, according to whether the lime 

 is quick acting or sluggish. The intense heat seems to break up the particles 

 of sulphur into about the physical condition of precipitated sulphur, and the 

 violent boiling makes a good mechanical mixture of the lime and sulphur. 

 Only a small percentage of the sulphur — enough to improve the adhesiveness 

 of the mixture — goes into solution, but if the hot mass is allowed to stand 

 as a thick paste the sulphur continues to unite with the lime, and at the end 

 of thirty or forty minutes enough of the reddish liquid is produced to burn 

 peach foliage and even apple foliage in some cases. Hence the necessity 

 for cooling the mixture as soon as the lime is well slacked. The finely 

 divided sulphur in mechanical mixture with the lime is depended upon for 

 the fungicidal action rather than the sulphids in solution, the latter being 

 harmful to foliage except in very dilute form. 



SELF-BOILED LIME-SULPHUR MIXTURE 



Unslacked lime 



Resublimed sulphur 

 Water 



8 lbs. 



8 lbs. 



50 gals. 



