Adequação de práticas culturais para o manejo de pragas do algodoeiro

Abstract

According to cotton crop diagnostic in the region of Semiarid, the pest occurrence is one of the most important hold back issue for the development of this crop. Among the cotton pests, the boll weevil Anthonomus grandis Boh. (Col.: Curculionidae) is considered the most important pest of cotton in this region where is low the adoption of appropriate pest management practices. Thus, this study investigated the impact of picking up reproductive structures falling on the ground and the adoption of pruning plant terminals to discard reproductive structures on boll weevil population. The studies were conducted in two localities and using different cotton varieties. In Paudalho County, PE, was set up a field study with four cotton varieties of white and colored fibers to define the appropriate age of pruning plant top. The results show that pruning plant top when plants exhibiting 50% of mature bolls or opening the first boll did not affect the yield parameters, but pruning plants with 50% of mature bolls took out more unproductive squares than plant at age of opening bolls. In Surubim County, PE, the adoption of pruning plants with 50% of mature bolls and pickivarieties BRS 201 of white fibers and BRS Rubi of brown fibers. The adoption of these practices resulted in taking out large number of insects from the fields, but not enough to drop the boll weevil population bellow economic threshold level within the same season due to the high level of infestation in the region. In the microparcels with caged plants in the field and monitored bollng up falling reproductive structures were studied using theweevil infestation, was found that the adoption of picking falling reproductive structures, pruning plant tops and both practices together reduced boll weevil population at the end of the experiment at rate of 2.8, 2.5 and 4.8 times, respectively. Thus, the adoption of these practices simultaneously, reducing the boll weevil population at rate of 4.8 times might cause significant effects on population between seasons and, hence, on that population returning to cotton fields in the next cotton season.