New York Agricultural Experiment Station. i6i 



water by boiling 15 or 20 niiiiutes. This makes the stock sohition 

 which can be loottled and kept until desired for use. For spraying 

 potatoes add two quarts of the stock solution (one-half pound white 

 arsenic) to the quantity of bordeaux required to cover an acre. This 

 is equivalent to an application of one pound of paris green per acre. 



In using the white arsenic stock solution with bordeaux mixture 

 prepared by the potassium ferrocyanide test it is always advisable to 

 add lime a little in excess of the amount required to satisfy the test 

 in order to prevent the possibility of injuring the foliage. In our 

 experience it has not injured the foliage in the least when used with 

 bordeaux. If used in lime water there must be plenty of lime or the 

 foliage will be injured. White arsenic was used with entire satisfac- 

 tion in both of the Salisbury experiments at Phelps and in the Sta- 

 tion experiments at Geneva and Riverhead. 



DIRECTIONS FOR SPRAYING. 



In general commence spraying when the plants are six to eight 

 inches high and repeat the treatment at intervals of 10 to 14 days in 

 order to keep the plants well covered with bordeaux throughout the 

 season. During epidemics of blight it may be necessary to spray as 

 often as once a week. ITsually six applications will be required. The 

 bordeaux should contain six pounds of copper sulphate to each 50 

 gallons. Whenever " bugs " or flea-beetles are plentiful add one 

 pound of paris green or two quarts of white arsenic stock solution 

 (See p. 160) to the quantity of bordeaux required to spray an acre. 



Thoroughness of application is to be desired at all times, but is 

 especially important when flea-beetles are numerous or the weather 

 favorable to blight. Using the same quantity of bordeaux, frequent 

 light applications are likely to be more effective than heavier applica- 

 tions made at long intervals ; e. g., when a horse sprayer having but 

 a single nozzle per row is used, it is better to go over the plants once 

 a week than to make a double spraying once in two weeks. 



