Water in pesticide application

Abstract

In plant protection a number of pesticide products, depending on formulation type, is applied previously diluted in water which differ in quality. The aim of the study was to determine the effect of water pH on pH value of spray liquids of fungicides (azoxystrobin, mancozeb), insecticides (thiamethoxam, cypermethrin), non-pesticide substances (complex fertiliser, adjuvant) and their mixtures. pH values of spray liquids were determined potentiometrically, immediately after preparation and after 24 h in the following waters: well water (Adice) - slightly alkaline (pH 7.90, 34.7 d°H, NO2 2.5mg/l); tap water (Novi Sad) - neutral (pH 7.42, 15.4 d°H) and surface water (Sava) - slightly alkaline (pH 8.15, 11.7 d°H, NO 2 0.18 mg/l, NH3 0.93 mg/l). Regardless of quality and pH of the water and pesticide compounds, pH value of spray liquids without complex fertilizer was in the range from 7.3 to 8.2 from application to 24 h. However, regardless of pH of water and pesticide compounds, all variants containing complex fertiliser had pH between 5.7 and 6.9, which points to possibility of correcting pH values of spray liquids with this fertiliser when the time of pesticide application coincides with fertilisation.