Cooperative Spraying Experiments. 



i6i 



to the more laborious jarring process (Fig. 39). The reasonable theory 

 of how the poison works was evolved from observations made nearly 

 twenty years ago (Cornell Bulletin No. 3) on the feeding habits of the 

 beetles. They feed more or less on the leaves, flowers and young fruits 

 in the spring and may thus get some of the poison. Some have thought 

 that the poison lodged in the crescent cut made by the curculios in egg- 

 laying, and that the newly-hatched grub got some of the poison in its first 

 meals, but this is not true, as the grub immediately tunnels into the fruit 

 and does not get into the cut at all. Paris green has been the poison 

 usually used in spraying for this pest, but in all my cooperative experi- 

 used stronger without 

 danger of injuring the 

 foliage. 



In 1904, I sent 170 

 pounds of the arsen- 

 ate of lead, in lots of 

 from 10 to 30 pounds 

 to 12 plum, cherry and 

 peach growers in New 

 York. They were re- 

 quested to use the poi- 

 son at the rate of 2 

 pounds in 50 gallons 

 of water or Bordeaux 

 and make two appli- 

 cations, one just after 

 the blossoms dropped 

 and another about a 

 week later. The pre- 

 ceding severe winter 

 killed the trees or 

 buds in some in- 

 stances and for other 

 reasons several of the 

 fruit-growers did not 

 use the poison spray. 

 Largely owing to the 

 fact that the curculio 



*-* 





^Af 





/ -I '--^ 







Fig. 41. — Mr. Wood's tins prayed plum tree. Note much 

 less fruit than on sprayed tree in Fig. 40. A fungous 

 disease caused most of the leaves to drop. 



did not appear in injurious numbers, the following experimenters re- 

 ported practically no difference between the sprayed and unsprayed trees : 



Ira Pease, Oswego, on plums and prunes. 



Freeman Pintler, Ontario, on peaches. 



II 



