In addition to direct negative effects on plants, extended
use of glyphosate has been suggested in some cases to
benefit disease causing microbes. Glyphosate may be
among the most important agronomic factors increasing
plant disease incidence in wheat (Triticum aestivum) and
barley (Hordeum vulgare) crops [40,41]. Glyphosate use in
silviculture has also been connected to blue stain fungi in
poplar [42]. Sublethal doses of glyphosate to plants can
decrease plant resistance to pathogens and herbivores by
reducing their secondary metabolite production (Figure 1)
and decreasing uptake of micronutrients (e.g., Mn) and
subsequent development of deficiency symptoms in nontarget
crops [32,43–46].