TOBACCO HORNWOEM INSECTICIDE. 7 



Before discussing the dosage of arsenate of lead required under 

 different conditions it will be well to compare the results obtained 

 by fanners with arsenate of lead with results obtained through field 

 applications made by agents of this bureau. 



RESULTS OF FARMERS' APPLICATIONS OF ARSENATE OF LEAD VERSUS RESULTS OF 

 APPLICATIONS MADE BY BUREAU AGENTS. 



Table 2 compares the results obtained by agents of this bureau 

 with results obtained by fanners upon the 27 fields recorded in Table 1 . 



Table 2. — Comparison of the best fourth of farmers' applications of arsenate of lead with 

 the best fourth of the applications of the same insecticide made by agents of the bureau. 



The farmers' application of 4| pounds per acre killed 5 per cent 

 less worms in 4J days than were killed by the application of 5^1,^ 

 pounds per acre by agents of the bureau in 3f days. Both dosages 

 did good work, but there is considerable advantage in favor of the 

 ^TO" pound dosage. Table 2 does not show a very great advan- 

 tage in favor of the 5^^ pound dosage as compared with the dosage 

 of 4| pounds, but something of the lasting effects of large dosages 

 must be learned before a proper conclusion can be drawn. Table 3 

 shows the lasting results of a large dosage very plainly. The exami- 

 nations of the experiments by agents of this bureau were made at 

 periods varying from 8 to 15 days after the applications, and are 

 compared with examinations made 9 to 12 days after applications by 

 fanners. The average period between application and exammation 

 will be seen to be practically the same. The tobacco was fuU grown, 

 promismg an average yield of 800 pounds per acre. 



Table 3. — Results of examinations made at the expiration of an average of 10 days after 

 applications of arsenate of lead made by agents of this bureau and by farmers. 



The results in Table 3 show conclusively that a 4-pound dosage 

 can not be expected to keep tobacco even approximately clean for 

 a period of 10 days, and that a dosage of 5 pomids will kiU a great 



