New York Agricultural Experiment Station. 379 



All of the above-mentioned a<l'vantages of spraying must be 

 taken into consideration when discussing the question, \\'ill it 

 pay to spray every season? 



In most of the recorded experiments on potato spraying, the 

 late blight has been an important factor, and hence these experi- 

 ments do not furnish a complete answer to the present question. 

 It is necessary to knoAv not only the benefit to be derived from 

 spraying in seasons when late blight is prevalent, but also the 

 benefit to be derived from spraying in seasons when there is no 

 late blight. Fortunately, the conditions have been such that our 

 experiments on Long Island during the past two seasons have 

 thrown considerable light on this very point. 



SPRAYING EXPERIMENT AT FLORAL PARK. 



In 1895 we made a spraying experiment* at Floral Park, Long 

 Island. A field of potatoes containing four and one-half acres 

 was divided into three equal plats. One plat Avas sprayed five 

 times with Bordeaux mixture, one plat was sprayed three times 

 with Bordeaux mixture and the remaining plat was not sprayed. 

 With the exception of spraying, the three plats were treated as 

 nearly alike as was possible in every respect. The Colorado 

 potato-beetles were kept under control by the use of Paris green. 

 On the sprayed plats the Paris green was appLf^d with the Bor- 

 deaux mixture in the first two applications. On the unsprayed 

 plat the same quantity of Paris green was used and was applied 

 in water by means of the sjjraying machine at the same time the 

 sprayed plats were treated the first two times. 



Throughout the entire season there was no trace of late blight, 

 even on the unsprayed plat, and so it might be thought that our 

 spraying had been unnecessary. But the early blight had been 

 prevalent and there had also been some flea-beetles on the un- 

 sprayed plat. Spraying with Bordeaux mixture had prevented 

 these eneimies from doing much damage to the sprayed plats and 

 as a consequence these plats gave a considerably larger yield 

 than the unsprayed plat. The plat sprayed three times yielded 



52 bushels of merchantable tubers per acre more than the un- 



1 



*For the details of this experiment see N. Y. Agrl. Exp. Sta. Bui. No. 101, pp. 73-76. 



