October, '21] serverix & others: beet leaf hopper 405 



EXPERIMENTS WITH A DUSTING MACHINE TO CONTROL 



THE BEET LEAFHOPPER (EUTETTIX TENELLA BAKER) 



WITH NICOTINE DUST 



By Henry H. P. Severin, Ph. D., California Agricultural Experiment Station. 



William J. Hartung, B. S., Spreckels Sugar Company, Agricultural 



Edward A. Schwing, B. vS., Experiment Station. 



WiLLLAM W. Thomas, M. S. 



The first experiments involving the use of dust preparations were 

 carried out on a small scale by Mr. W. W. Thomas to control the beet 

 leafhopper {Eutettix ienella Baker). The work was conducted near 

 King City in the Salinas \^alley during the 1919 outbreak of the pest. 

 Dusting operations were started in the early part of July and continued 

 until the return flight of the overwintering adults to the foothills had 

 occurred during October. 



Daily applications of dust mixtures were used at first to determine the 

 relative value of the insecticides. The plots of beets comprised 1 /lOO 

 of an acre or 12 rows, 20 feet long. Five rows of beets in each plot were 

 dusted as soon as the seeds germinated and seven rows received no 

 treatment. In later experiments the dust preparations showing a 

 possibility of results were applied daily, biweekly and weekly on larger 

 plots of beets. These plots consisted of 1 /lO of an acre or 25 rows 100 

 feet long. Twelve rows in each plot were dusted and 13 rows were used 

 as a check. The dust w^as applied with a hand duster. The percentage 

 of curly leaf existing with the use of dilTerent dust mixtures at the end of 

 sLx weeks is indicated in table I. 



With the harvesting of beets in the vicinity of the experimental fields 

 an enormous congregation of adults was caused in the plots and hence no 

 definite conclusions can be drawn as to the value of the dust as a method 

 of control. When the summer broods make their appearance, flights on the 

 part of the males associated with mating have been observed in other 



