Pomona College Journal of Economic Botany 45 



Formula No. 1, the sodium sulphide spray with the distillate added, seemed 

 superior to either of the others, practically eliminating the red spider and 

 promising high efficiency against the young scales. Occasional burns on 

 the fruit where a drop would collect and evaporate, and slight injury to 

 the young growth and lemons just setting, were more than offset, as we 

 thought, by its greater efficiency against spider and scale. Four power sprays 

 were soon at work covering the orchard at the rate of about 6 acres per 

 day. They were at work steadily for nearly three months and our ex- 

 penditure exceeded $3,000 or more than 11c per tree. Our faith in this 

 combination was supported also from the following letter from Mr. R. C. 

 Allen, of the Sweetwater Fruit Company, San Diego Co., California : 



Figure 20. Tank for receiving lime after it has been slacked and is ready to mix with 

 copper sulphate. The agitator is the special feature of this tank. 



"Bonita, California, June 16, 1909. 

 "Mr. Jas. D. Culbertson, Limoneira Co., Santa Paula, Cal. 



Dear Sir: We have your letter of the 11th in regard to spraying with 

 sulphur. This is no new thing with us, as we have been using it systematically 

 for the last ten or twelve years. We use about 10 pounds of sulphur to 

 the 200 gallon tank. We dissolve the sulphur with at least half as much 

 caustic soda, our method being to moisten the sulphur first and then add 

 the soda and heat over a fire, being careful not to let it boil over. Some 

 people get satisfactory results without the fire, but we do not. 



It may be some advantage to use caustic potash instead of soda for the 

 reasons you mention. But so far as it affects the tank, or upon the hands of 

 the sprayers is concerned the caustic principle in the potash or soda is en- 

 tirely exhausted in fusing the sulphur. We advise the use of a good grade 

 of sublimed sulphur in preference to the ground. The latter contains a good 

 deal of impurities and is much more difficult to dissolve. 



We have hitherto used galvanized tanks on our spraying machines but we 

 have recently bought a bean outfit which has a wooden tank. As we have 

 used the same iron tank for 5 or 6 years and it is still in good condition, you 

 need not fear any trouble on that score. 



