48 Pomona College Journal of Economic Botany 



winter and spring crop of lemons for 1910 was nearly 50% short of the 

 previous year's crop during the same portion of the year, while the 1910 

 summer crop was the greatest summer crop we have ever produced. The 

 lemons that were picked this last summer came from blosoms that followed 

 immediately the fungicide spraying of the year before. Other factors may 

 have contributed to this result, yet it may be that the spraying was not the 

 smallest factor as is evidenced by Prof. Rolfs in his article on Citrus Bloom 

 Dropping. . (See under lemon below heading of Destructiveness.)" 



The methods used in the control of this fungous parasite must necessarily 

 be preventative. After the disease is once established in the tissues of the 

 host it can never be destroyed without destroying the host also, because it 

 works within the tissues, and until the acervuli appear upon the surface to 

 expose its conidia or spores for distribution, it is protected by the epidermal 

 layers of the host. 



Many methods have been recommended. It may be that certain measures 

 taken in some localities may prove impractical in others, while a combina- 

 tion of all may be successful in special cases. 



We shall take up the discussion, then, under the following heads : Spraying, 

 Pruning, Orchard Practice (to include Cultivation, Irrigation and Fertiliza- 

 tion), and Packing House Methods. 



In all the work that has been done with sprays in combating the wither- 

 tip, the Bordeaux Mixture stands out as the most efficient, and we are 

 wont to give it the first place in this consideration. 



The formula now used at the Lemoneira orchard is known as the 4-4-50 or, 



The task of mixing these chemicals, where so much of the spray is used, 

 is no small thing in itself. A great deal of study has been given to the 

 construction of suitable mixing apparatus. 



The first consideration is to get the materials high enough on a platform 

 so that they can be easily and rapidly placed in the spraying tanks of the 

 power machines. This is done by constructing, at convenient places in the 

 orchard, platforms large enough to hold a large box for slacking lime, a lime 

 solution agitator, and a vat for dissolving the bluestone. Such a platform 

 is about 12x12 feet square and A l / 2 feet high. A large standpipe for filling 

 the tanks is a necessity or the water must be pumped into the tank while the 

 solution is being added. 



The lime is first slacked in a common vat for that purpose. The great 

 trouble has always be«n to keep the slacked lime agitated properly when it 

 was being drawn off to mix with the bluestone in the spraying tank. This 

 problem has been met with a special agitator for this purpose (Fig. 20). 



METHODS FOR CONTROL 



SPRAYING 



Unslacked lime 



Copper sulphate (bluestone) 

 Water 



50 gals. 



4 lbs. 

 4 lbs. 



