Some non-selective herbicides used in no-till system may be partially neutralized in water utilized as spray vehicle. This can occur if the water employed contains orgânic or mineral coloids in suspension, which may adsorb herbicide molecules. The objective of this research was to investigate the effect of water from diferent origins and chemical characteristics on glyphosate activity. Treatments consisted of various mineral pource waters (Caxambu, Da Guarda, Fonte Azul, Fontes de Belém, Fonte Ijuí, Fonte da Ilha, Itati, Minalba e Sarandi) and also distitled water utilizing glyphosate rate of 450 g/ha a. e., that were applied over oat plants. Phytotoxicity loas visually evaluated at 7, 12, 15, 21 and 28 days after applications (DAA). It was observed that only ar 12 and 15 DAA occured diferences between waters. Da Guarda, Fonte Azul, and Fonte Ijuí reduced glyphosate activity in comparison to Fonte Sarandi, Itati and destilled waters. In the latest tuo evaluations (21 and 28 date) none of the mineral waters differed from destilled water shouing no negative effects of such waters on herbicide action of glyphosate.
Diluent pH; mineral waters; salts content; Avena strigosa
