56 



MASS. EXPERIMENT STATION BULLETIN 202. 



Hammond's Copper Solution, a commercial preparation which has 

 been used by florists in attempts to control greenhouse rusts, was next 

 tested. The stock solution as purchased was analyzed by Mr. T. O. Smith, 

 assistant chemist at the New Hampshire Agricultural Experiment Sta- 

 tion, and found to contain 0.018 gms. copper in 1 c.c. of solution. The 

 manufacturers recommended that it be applied at the rate of 1 quart 

 of the stock solution to 25 gallons of water, that is, a solution containing 

 0.018 per cent copper. The results of the tests are given in Table 9. 



Table 9. — Effect of Various Strengths of Hammond's Copper Solution on 

 the Germination of the Urediniospores of P. Aniirrhini. 



It is evident that Hammond's Copper Solution, even when used at 

 ten times the recommended strength, does not prevent germination of 

 urediniospores of P. Antirrhini. In connection with this work the action 

 of Hammond's Copper Solution on carnation rust was also tested, and 

 at the recommended strength it was not toxic, the germination of the 

 urediniospores of U. Caryophyllinus (Schrank) Wint. relative to check, 

 100, being 56. 



Bordeaux mixture was next tested. The Bordeaux mixture used 

 contained copper sulfate and calcium oxide in the approximate ratio of 

 1 : 0.3; that is, calcium oxide was added to slight alkalinity. This formula 

 was used for the sake of convenience, but the same results would be 

 obtained with any current formula, for the unit copper is equally toxic 

 in acid, neutral and alkaline Bordeaux mixtures (Butler, 1915). The 

 Bordeaux mixture used in the tests was diluted to various strengths, 

 so as to contain the following percentages of copper sulfate: 0.0156, 

 0.0312, 0.0625, 0.125, 0.25, 0.5, 1, 2 and 4. The results are shown in 

 Table 10. 



