22 FARMERS* BULLETIN 933. 



forms are easily washed off by rain or dissipated by dew. Direc- 

 tions for making lime-sulphur solution are given in other publica- 

 tions of the department. 1 For these pests it is best to use lime- 

 sulphur not weaker than 1 gallon to 75 of water. The maximum 

 strength to be used will depend entirely upon the season of the year 

 and what other objects the grower may have in view by spraying. 

 This material can not be used in combination with the oil sprays, but 

 it may be used in combination with the tobacco sprays for thrips in 

 the bloom. 



SODA-SULPHUR SOLUTION. 



The main value of the soda -sulphur solution consists in the prop- 

 erties which enable it to be used in combination w T ith the oil emul- 

 sions. Owing to the superiority of lime-sulphur solution the use of 

 soda-sulphur solution alone is not advised. It has a distinct place, 

 however, in forming a good combination spray for white flies, scale 

 insects, and mites. It is made as follows : 



Formula. 



Flowers of sulphur pounds 30 



Caustic soda (98 per cent) do 20 



Water __gallons__ 20 



To remove the lumps from the sulphur place a wire screen over the 

 barrel and rub the sulphur through with the hands, then slowly add 

 about 3 gallons of water and stir so as to form a thin paste. The 

 caustic soda should then be added and the entire mixture stirred 

 vigorously. Some growers add the caustic soda gradually to pre- 

 vent too vigorous boiling, and others add it all at once with water 

 enough to prevent too vigorous boiling. It is also practicable to 

 dissolve the caustic soda in about 4 gallons of water before it is 

 added to the sulphur. The boiling will be quite violent and it may 

 be necessary to add a gallon or more of water during the process, 

 but whether or not this is necessary can be determined by the 

 operator. 



The main difficulty in making this formula is that too great heat 

 is generated, which liquefies the sulphur before it can be acted on by 

 the caustic. If sediment forms this has been the cause. To prevent 

 this excessive heat add more water in the beginning and during the 

 process. After boiling has ceased add about 16 gallons of water. 



For spraying against red spiders and rust mites use 1 gallon of 

 this stock solution to 40 gallons of water. When used with the oil 

 sprays the strength should be a little weaker than if used alone. 

 When so used dilute 1 gallon to 50 gallons of water. If it is to be 



1 Farmers' Bulletin 908, " Information for Fruit Growers about Insecticides, Sprayinp: 

 Machinery, and Important Insect Pests," by A. L. Quaintance and E. H. Siegler. 



