Long-term studies on field-grown soybean during 1997–2007 demonstrated consistently higher root colonizationby Fusarium spp. on GR cultivars with glyphosate (Kremerand Means 2009). Soybean roots from plants receiving noor conventional postemergence herbicides exhibited lowFusarium colonization, and nontransgenic (non-GR) culti-vars always had the lowest root colonization. Subsequentstudies showed that label rates of glyphosate applied to GRsoybean resulted in exudation of glyphosate from rootswith simultaneous exudation of high concentrations ofsoluble carbohydrates and amino acids that favoured fun-gal infection (Kremer et al. 2005). Other reports indicatethat although glyphosate is considered inactivated by rapidsoil adsorption, glyphosate may serve as a substrate tosome micro-organisms (Arau´jo et al. 2003; Kuklinsky-Sobral et al. 2005). Thus, rhizosphere-inhabiting Fusariummay metabolize glyphosate in root exudates as a source ofP, C and energy (Castro et al. 2007).