The Impact of Pesticides - Academy Publish

(HAILE et al., 1998). Earlier results report defoliation levels of until 50% withoutyield reduction (PICKLE & CAVINESS, 1984). Many of these studies used todetermine the economic threshold currently recommended for controlling the majordefoliator pests, however, were carried out in the 70’s or 80’s, although somerecently published research papers have shown that these levels are still reliable(COSTA et al., 2003, REICHERT; COSTA, 2003). Among the recent researchworks, BUENO et al. (2010) showed that even the newer cultivars, regardless of thetype of growth habit (determinate or indeterminate), tolerate the defoliation levelsadvocated by the economic threshold without a significant reduction in productivity(Figure 6). So far, there is no scientific evidence showing that more recent cultivars(early maturity group and indeterminate growth habit, for example) are moresensitive to leaf area losses.Figure 6. Mean soybean production (±SE) with seeds at 13% moisture afterdifferent defoliation intensities (%) at different developmental stages of twosoybean cultivars (M7908RR and M7637RR) grown in the municipality ofMorrinhos, State of Goiás, Central Brazil, during the 2009/2010 crop season. Meansfollowed by the same letter are not statistically different between each other by theTukey test at 5% probability in each experiment (adapted from BUENO et al. 2010).AcademyPublish.org - The Impact of Pesticides172