403 



791. . 1980. Effectiveness of diflubenzuron (Dimilin) for boll weevil 

 suppression in Texas. Southwest. Entomol. Suppl. (Summary) 1: 36-37. 

 The results reported in this study suggest that adequate season-long control 

 of boll weevils with diflubenzuron, even with light to moderate infestations, will 

 be difficult and may require special management practices. The most effective 

 method of using diflubenzuron for boll weevil control appears to be a program 

 designed to suppress reproduction by overwintered females. Due to the mode of 

 action of diflubenzuron (i.e., inhibited reproduction) and the boll weevil's 

 capacity for rapid population increase, the 1st application must be made to cotton 

 when fruiting is in the "pinhead square" stage or earlier, before oviposition 

 begins. The unusual persistence of diflubenzuron on cotton does not result in 

 extended activity against the boll weevil, and it apparently must be applied at 

 regular intervals of 5-7 days for an extended period to maintain control. This 

 type program would be designed to limit boll weevil reproduction long enough to 

 obtain an acceptable boll set before the populations develop to a damaging level 

 after th^ termination of treatments. In instances where the overwintered boll 

 weevil population is large, diflubenzuron applications may have to be supple- 

 mented with fall treatments for diapausing weevils and/or with at least 1 appli- 

 cation of a conventional insecticide in the spring to reduce the number of adult 

 DoH weevils that survive the winter. Diflubenzuron applications- should be 

 integrated with proven management practices such as planting short season cotton 

 varieties and early harvest and stalk destruction. In addition, the use of the 

 IGR in community or area-wide programs would produce better results than when 

 used on an individual farm basis. Research conducted in Texas indicates that 

 diflubenzuron does have a place in boll weevil management. However, both the 

 advantages and disadvantages related to its use must be considered. 



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