Association of glyphosate with other agrochemicals: the knowledge synthesis

Abstract

The association of agricultural chemicals complies with many objectives, such as the simultaneous control of organisms, dosage reduction, increase in the efficacy and prevention of cases of resilience to pesticides. The current paper aims to summarize information on the association of glyphosate with nutrients, herbicides and other pesticides. The association of glyphosate with polyvalent cations (e.g.: Ca and Mn), in general, reduces the efficacy of the herbicide, which can be overcome with the addition of ammonium sulfate to the application spray. The association of glyphosate with other herbicides depends on the used dosages, on the vegetable species, on the evaluation period, on the plant's development stage and on the biochemical compatibility between the action mechanisms of the herbicides. The association of glyphosate with systemic herbicides, in general, presents higher compatibility and benefits in contrast to the mixture with contact herbicides. The association of the glyphosate with auxin mimicking agents, in general, results in a synergetic effect. The mixture of glyphosate with ALS inhibitors may generate synergetic, additive, or antagonistic effects, presenting higher dependence on the doses of glyphosate on the mixture. There are many examples of antagonism among glyphosate and contact herbicides, such as inhibitors of GS, FSII, FSI and PROTOX. There is a lack of publications on glyphosate associated with fungicides or insecticides, and they do not prove synergetic or antagonistic effects of this mixture. However, papers that document the metabolization of glyphosate by plants suggest the need to investigate the impact of insecticides and fungicides in the action of the herbicide.