296 



BOARD OF AGRICULTURE. [Pub. Doc. 



In spraying operations against the elm-leaf beetle the end 

 to be desired is the thorough covering of the foliage, particu- 

 larly the under surface, with a mist-like spray. For this 

 reason nozzles that throw a stream are undesirable, as well 

 as being wasteful of the spraying mixture. In our work 

 against the g3'psy moth we have found the four-way modified 

 cyclone nozzle (fig. 4) to give the most satisfactory spray. 

 Other good nozzles are the vermorel and cyclone. 



Fig. 3. One-quarter-inch hose with improved couplings. From Forbush, report Massa- 

 chusetts Board of Agriculture, 1898. 



It is not necessary to use glucose to cause arsenate of 

 lead to adhere to the foliage. Experiments made under the 

 direction of the gypsy moth committee have shown that no 

 substantial gain is made by the use of glucose, a result that 

 has been confirmed by the independent investigations of City 

 Forester Gale at Springfield. 



Fig. 4. Improved four-vcay nozzle. From Forbush, report Massachusetts Board of Agri- 

 culture, 1898. 



Arsenate of Lead. — This insecticide is now generally 

 used against the elm-leaf beetle, and possesses the merits of 

 being harmless to the foliage and of adhering to it in an 

 effective condition for a long period. It is prepared by mix- 

 ing a solution of arsenate of soda with a solution of acetate 

 or nitrate of lead, when arsenate of lead is formed as a curdy 

 white precipitate. The following table, adapted from Smith,* 



* For an excellent and comprehensive treatise on the preparation of arsenate of 

 lead, see article by F. J. Smith in report of Massachusetts Board of Agriculture, 

 1897, pages 357-369. 



