FARMERS BULLETIN 867. 



COMPARISON OF RESULTS OBTAINED BY THE USE OF PARIS GREEN 

 AND ARSENATE OF LEAD IN 1916 IN KENTUCKY AND TENNESSEE. 



In the year 1916 records of the results obtained from dust apph- 

 cations of both Paris green and arsenate of lead, by farmers in several 

 counties in Kentucky and Tennessee, were made to determine the 

 relative efficiency of these two insecticides. 



On 92 fields upon which they had applied Paris green at the aver- 

 age rate of 1.31 pounds per acre, 22.7 per cent of the worms were 

 found dead 9 days after the application. On 108 fields upon which 

 they had applied arsenate of lead at the average rate of 3.2 pounds 

 per acre, 48.14 per cent of the worms were found dead 13 days after 

 the application. 



No better comment could be made upon the comparative insecti- 

 cidal values of Paris green and arsenate of lead than the foregoing 

 statement of results, particularly so when it is considered that the 

 average dosage of Paris green was as large as could be applied with 

 reasonable safety and that the dosage of arsenate of lead could have 

 been doubled without causing any serious damage to the tobacco 

 plants. 



Although an examination of these fields 3 to 5 days after the 

 applications undoubtedly would have shown that the hornworms 

 were being killed in considerable numbers in many instances, yet it 

 would have shown also that the fields were not being kept free of 

 worms. The records show also that with a light dosage of arsenate 

 of lead more than twice as many worms were being killed as with 

 the usual dosage of Paris green. 



Table 1 shows the average results of the best fourth of the field 

 records mentioned above. 



Table I. ^Comparison of applications of Paris green and arsenate of lead made by farm- 

 ers in Kentucky and Tennessee, using the best fourth of the records of each. 



The foregoing comparison of the best results obtamed by farmers 

 brings out two facts very clearly: First, farmers, on the average, are 

 not keepmg tobacco free of hornworms in a satisfactory maimer with 

 Paris green; second, they are securmg much better results with 

 arsenate of lead than with Paris green. 



