EXPERIMENT STATION BULLETINS. 337 



when the arsenite is used alone, as the soluble arsenic unites with the 

 lime, forming an arsenite of lime, a substance practically insoluble. 



For the apple, pear, and plum trees, one pound of London purple can 

 be used with safety in 250 gallons of modified eau celeste, or 300 gallons 

 of ammoniated copper carbonate, if applied before July 1, and we seldom 

 need to use the arsenites after that date. 



Lodeman of the Cornell University experiment station,* found a slight 

 injury from applications made during August and September, and it would 

 hardly be desirable to use them at that time, although if really necessary 

 to spray, both for insects and fungi, the slight injury to the foliage that 

 would be caused, would not have any marked effect on the tree. The 

 peach is so badly affected by soluble arsenic that, if any combination is to 

 be used upon peach trees, Bordeaux mixture should be selected as the 

 fungicide. Although London purple is more soluble than Paris green in 

 water, the solubility of the former in ammonia is the greater, and is 

 therefore to be preferred for use in ammoniated compounds. 



HOW TO OBTAIN THE MATEEIALS. 



The retail price charged by druggists for the chemicals required for 

 making these mixtures, has prevented many persons from using them. 

 The increasing demand, however, has induced several firms to arrange for 

 supplying them to fruitgrowers at wholesale rates, and that they may 

 save to the consumer the expense of freight or express charges, on small 

 quantities, for long distances, distributing depots will be provided in 

 different parts of the country. 



Among the firms making a specialty of this business are the Nichols 

 Chemical Co., 45 Cedar St., New York, and W. S. Powell & Co., Baltimore, 

 Md. The latter firm also manufactures liquid and dry copperdines, pre- 

 pared Bordeaux mixture, and other ready-mixed fungicides. The crystal 

 sulphate of copper can be obtained in five-pound packages at five cents per 

 pound, but in barrel lots the price is only three and one half cents per 

 pound. The powdered carbonate of ammonia costs thirteen cents per pound 

 in ten -pound lots, or eleven cents by the barrel. For three applications 

 the materials for spraying a full-size apple tree would cost from two and 

 one half to three cents, or if the formula was reduced one half in strength, 

 as is recommended by Prof. Chester, of Delaware, the price would be cor- 

 respondingly less. The commercial mixtures are for sale by several of the 

 largest seedsmen, and when one has only a few trees or vines to spray, 

 although the price charged for them seems unnecessarily high, they will 

 be nearly as cheap as the chemicals at drug store prices. If of standard 

 strength, as they should be, they will answer as well as, and be easier to 

 apply, than the home-made mixtures. 



Where any number of trees are to be sprayed, the chemicals at whole- 

 sale rates will be considerably cheaper, and if the powdered copper sul- 

 phate and powdered carbonate of ammonia are used, the trouble of mixing 

 will be very slight. 



AEE FUNGICIDES AND ARSENITES DANGEROUS? 



When Paris green was first used on potatoes, for the Colorado beetle, 



* Bulletin 35 published December, 1891. 



43 



