HERBICIDE ACTION OF GLYPHOSATE AS A FUNCTION OF WATER USED AS DILUENT AND OF AMMONIUM SULPHATE ADDED TO SPRAY SOLUTION

Abstract

Probable negative effects of high pH and of salts present in spray solution on herbicide activity may be overcome through addition of substances such as acids and/or nitrogenous compounds. The objective of this research was to evaluate the effect of waters from different origins, and of addition of ammonium sulphate, on herbicide action of glyphosate. Treatments consisted of glyphosate rates of 90 and 180 g/ha a. e., with and without ammonium sulphate (1.25% p/v), that were diluted in mineral waters Fonte Azul, Fonte Ijuí, Fonte Sarandi, and distilled water, and applied over oat plants. Phytotoxicity was evaluated at 5, 11, and 19 days after applications. As resulta, it was observed for the three evaluations that glyphosate rate of 180 g/ha caused higher toxicity than did 90 g/ha, what was repeated for oat dry manar. Also, two evaluations indicated that addition of ammonium sulphate to spray solution increased herbicide activity. Only at the latest evaluation Fonte Sarandi water originated higher glyphosate action on oats than Fonte -Azul and distilled waters. It is demonstrated that herbicide activity of glyphosate is not greatly affected by the type of diluent employed, but that addition of ammonium sulphate increases its phytotoxicity.