POISONING COTTON-BOLL WEEVILS. 



13 



TIME OF APPLICATIONS. 



WHEN TO BEGIN POISONING. 



The technique of application is obviously much more important 

 than the actual poison utilized, if a poison of satisfactory degree of 

 toxicity be selected. As has been mentioned, very doubtful profits 

 were shown by early-season applications, and the most definite gains 

 resulted from treatments made while the infestation was at its height. 

 This is evidently due to a combination of conditions which need 

 not be discussed in detail here, but which caused an application 

 made at the time the weevils were doing their maximum injury to 

 the crop to be far more effective in their control. This time, of course, 



Fig. 10.— Power dusting machine in operation at Tallulah, La., April 26, 1917, showing type of dud tog 



developed. 



varies considerably under different conditions and in different seasons, 

 but is usually the time when the cotton manifestly slackens in bloom- 

 ing, and, while the experiments are not yet completed to the point 

 of outlining definitely just when the most effective season of appli- 

 cation will be, it will probably be found to be at about this time. 



INTERVAL BETWEEN APPLICATIONS. 



The time interval between applications is another important point 

 which must be determined but concerning which comparatively little 

 is known as yet. In most of the tests conducted so far the applica- 

 tions have been repeated at weekly intervals more as a matter of 

 convenience than for any particular reason, but it seems prob- 

 able that about once a week will constitute an effective application. 



