257 



damage (Bulletin 67, New Jersey Station, May 3, 1890). One of these 

 is a kerosene emulsion and the other a fish oil soap, which it is claimed 

 will also kill the Cabbage Aphis. 



The Effects of Arsenites upon plants.* — Mr. C. W.Woodworth, the ento- 

 mologist of the Arkansas Experiment Station, has published a little 

 fourteen-page bulletin under this head. His methods seem to have 

 been careful and his conclusions appear justified from his experiments, 

 although in some respects they differ from those reached by Gillette and 

 other recent experimenters. We give his conclusions in full : 



(1) The injury from white arsenic is seen compaiativelj'^ very soon after it is ap- 

 plied. London purple is almost as active. 



(2) Paris green does its injury much more slowly. 



(3) Young leaves are affected much more quickly than are the old ones. 



(4) Applications to the lower side of a leaf produce injury more quickly than if 

 the poison is applied above. 



(5) Except in the case of young leaves, it seems to be the rule that where the great- 

 est injury is produced, a greater proportion is early apparent. 



There are certain conclusions of practical importance that deserve to be emphasized. 



Where the plant is easily injured, and the choice is between Paris green and Lon- 

 don purple, Paris green is better in every particular. 



Spraying with the arsenites has become a recognized part of the culture of some 

 plants. With such plants varieties could be produced by selection to which strong poison- 

 ing tvoiild do no injury. 



When as is often tlie case it would be as effectual, it should be remembered that a 

 light spraying from above is the safest. 



Plants can be sprayed with equal or more safety when the leaves are young than 

 later in the season. 



Freshly mixed white arsenic promises to be one of the very best of the arsenites 

 and at the same time the cheapest. 



'Arkansas Industrial University Agricultural Experiment Station, Bulletin 14, 

 September, 1890. 



