8 



FARMERS BULLETIN 819, 



monly against the biidworm: Arsenate of lead, antimony sulphid, 

 Paris green, tri-potassiiim arsenate, ortho-arsenite of zinc, antimony 

 arsenate, and antimon}' oxid. These were tested in varying strengths 

 and in combination with corn meal, gypsum, and fuller's earth as car- 

 riers. Of all the poisons used, Paris green, arsenate of lead, and 

 golden antimony sulphid gave the most promising results, although 

 there is a great variation in the efficiency and cost of application of 

 these poisons. Corn meal was found to be the most satisfactory 

 carrier. 



Table 1 indicates the relative average cost per acre per season of 

 antimony sulphid, arsenate of lead, and Paris green, as well as the 

 percentage of leaves free of budwoi'm and poison injur3\ The cost 

 data are based upon results obtained on 51 plantations where 476 

 acres of tobacco were treated throughout the season. It was found 

 that an average of 4.17 bushels of meal were necessary to the treat- 

 ment of 1 acre. In calculating the total cost for the treatment of 

 an acre, corn meal was valued at $1 per bushel. The prices per 

 pound of antimony sulphid, arsenate of lead, and Paris green were 

 taken as 3.5 cents, 25 cents, and 30 cents, respectively. 



Table 1. — Rclatirc cffieicncii and cconoiini of (nititiioii ii siiliiliid. (irscndic of lead, 

 and Paris arccn in controlluKj the tobacco hndironn. 



Per cent 

 of lea\es 

 free of 

 budworm 

 and 

 poison 

 injury. 



Antimony sulphid, 1 poimd^ com meal, 24 pounds . 



Arsenate of lead, 1 pound; corn meal, 75 pounds 



Paris green, 1 pound; corn meal, 150 pounds 



98.25 

 92.50 



From the foregoing table it will be seen that where antimony 

 sulphid had been used at the rate of 1 pound to 24 pounds of corn 

 meal, 98.35 per cent of the leaves were free from budworm and 

 poison injur}^; and that where arsenate of lead had been used at the 

 rate of 1 pound to 75 pounds of corn meal, 98.25 per cent of the 

 leaves were perfect. The cost of the applications of antimony sul- 

 phid per acre per season was $2.26 more than for the arsenate of 

 lead, and of course the difference of one-tenth of 1 per cent in the 

 efficiency of these applications in favor of the antimony sulphid 

 would not compensate for the extra expense. 



Where Paris green had been used at the rate of 1 pound to 150 

 pounds of corn meal, 92.5 per cent of the leaves were free from in- 

 jury — 5.75 per cent less than where arsenate of lead had been ap- 

 plied — ^but the cost of application per acre per season was 26 cents 

 less than for the arsenate of lead. Since the injury following the 



