The Impact of Pesticides - Academy Publish

Figure 5. Graphical representation of the moment in which the pest controlmeasures have to be adopted on the soybean field according to the Integrated PestManagement (IPM) recommendations.It is exactly regarding to the Economic Thresholds in which some questions on theviability of this technology relies. The economic threshold levels for soybean pestwere determined years ago (1980’s). Thus, it is the frequently questioned detailsabout its nowadays validity, chiefly considering the newer and more productivesoybean cultivars, sometimes of different cycle and growth habit (early cycle andindeterminate growth habit). Aiming at eliminating this kind of doubt, someresearch results will be following discussed, focusing specially on the more recentdata, to validate these threshold levels and offer the necessary confidence to growersnecessary to the use of this technology.Economic Threshold for Defoliator InsectsThe level of defoliation tolerated for the soybean crop before starting any controlmeasure may slightly vary in different countries of the world. For example, in theUS the defoliation level tolerated before start spraying insecticide is 35% at thevegetative stage of the crop and 20% at the reproductive stage (ANDREWS et al.,2009). In Brazil, the economic threshold recommended to initiate the control ofdefoliator insects is 30% defoliation at the vegetative stage or 15% when the crop isat the reproductive stage (TECNOLOGIAS, 2010). It is important to emphasize thatthe soybean plant tolerates some defoliation without significant decrease on yieldAcademyPublish.org - The Impact of Pesticides171