8 FARMERS BULLETIN 867. 



many worms in 10 days, since the examinations of the 5-pound 

 dosage showed nearly 2^ times as many dead worms as in the case 

 of the 4-pound dosage. It is very evident that large tobacco must 

 be given at least a 5-pound dosage if it is to be kept reasonably free 

 of worms for more than a few days. 



DOSAGE OF ARSENATE OF LEAD REQUIRED. 



The foregoing records were all taken from fields upon which only 

 one dosage of lead arsenate was applied. The tobacco was practically 

 full grown and, as a rule, was infested heavily with honiworms, many 

 of which were half grown or larger; under such conditions a 5-pound 

 dosage of arsenate of lead is absolutely necessary. It is better, 

 however, not to rely upon one application to keep tobacco clean, 

 for one good application can not be expected to do satisfactory work, 

 under average conditions, for more than 10 days. Therefore, in sea- 

 sons during which the moths deposit eggs in considerable numbers 

 over a period much greater than 10 days, another dosage of an in- 

 secticide must be applied or the worm^ must be hand-picked. 



AT LEAST TWO DOSAGES RECOMMENDED. 



Under usual conditions in the ''Black Patch" in Kentucky and 

 Tennessee at least two dosages should be given. The size of the 

 dosages must be governed by the size of the worms. If the worms 

 are small and the tobacco is not more than half grown, a 3J-pomid 

 dosage per acre, evenly applied, wiU be sufficient. This may be 

 followed by a dosage of from 'S\ to 4 pounds when small worms again 

 appear in any considerable numbers. If, on the other hand, worms 

 are large at the time of the first application, not less than from 4 to 

 4§ pomids per acre should be applied. If the tobacco is large, 5 

 pounds per acre should be used. The time and necessity for a second 

 dosage must be determined by an examination of the fields at inter- 

 vals of two or three days after the first application, and the size of 

 the dosage should be governed by the size of the tobacco and number 

 of worms. 



Table 4 wiU furnish a good working basis for applications of arsenate 

 of lead in most cases. 



