14 BULLETIN 875, U. S. DEPARTMENT OF AGRICULTURE. 



chine investment per acre too high. On the other hand, it is un- 

 doubtedly the wisest policy to utilize methods which will give the 

 greatest possible degree of control during the first few years when it 

 is necessary for everyone to feel his way, more or less, in arranging 

 the poisoning schedule. Consequently, it is urged that poisoning be 

 attempted only under such conditions as will justify a sufficient 

 machinery outlay to permit poisoning at about a four-daj^ time 

 interval. 



NUMBER OF APPLICATIONS. 



The question as to the number of applications is closely correlated 

 with that of the time interval and is one which every man must de- 

 cide for himself by experience, as the number will vary widely under 

 different conditions. In the large Delta plantations, where the ma- 

 jority of the work has been conducted in the past, it has been found 

 that weevil control throughout the season in the cuts most heavily in- 

 fested and requiring the earliest treatment in the spring has necessi- 

 tated from four to six applications with a time interval of one week. 

 Other cuts more distant from hibernation quarters and thus more 

 lightly infested required three, two, one, or no applications. In two 

 years' work en thousands of acres handled on this basis, the average 

 number of applications for all cotton acreage involved has been 

 something less than two. Where infestation is more uniformly dis- 

 tributed at the outset and general poisoning is necessary, it has been 

 found advisable to figure on an average of about four applications, 

 and in case of an excessively rainy season, five or six applications. 

 These figures are based on a one-week time interval, as this interval 

 lias been the one adopted in the majority of work so far. With a 

 shorter time interval, however, control can be secured with about 

 three applications. This office is now planning to open a number of 

 mall experiment stations in nearly all representative districts of 

 the cotton belt. By conducting control tests at all of these at the 

 same time it will soon he possible to designate much more definite 

 rules of procedure under the varying conditions found in these 

 different districts. 



TIME TO STOP POISONING. 



The time to step poisoning has been more or less covered by the 

 discussion of the number of applications but it is probably well 

 to outline briefly the conditions governing this. The idea is to 

 maintain weevil control below the point of loss to the crop long 

 enough for the plants to set as many bolls as they can mature and 

 also to protect these beyond the danger of weevil puncturing. 

 Furthermore, there is nearly always a time when the plants cease 

 to retain any more fruit. In many cases they not only discontinue 

 squaring and blooming but shed the young bolls as fast as they are 



