Effects of mixtures of fungicide, insecticides, complex fertilizer and adjuvant depending on water hardness

Components in the mixture have different physicochemical properties, purposes, modes of action and are often differently formulated. Currently, it has become a common practice to add non-pesticidal components in mixtures. However, there is little data on the effects of water quality on biological activity of plant protection products i.e. prepared spray liquids. The aim of this study was to determine the fungicidal effect, depending on the components in the mixture and water hardness. In this study, a mixtures of fungicide (azoxystrobin - Quadris 0.75 l/ha), insecticides (thiamethoxam - Actara 25-WG 0.07 kg/ha, cypermethrin - Cipkord 20 EC 0.3 l/ha), complex fertilizer (Mortonijc plus / M+/ 3 kg/ha), and an adjuvant (Silwet L-77 0.1 l/ha) were used. Nine variants (eight mixtures and one single fungicide spray liquid) were tested. Spray liquids were prepared using water of different hardness: tap water from Novi Sad - slightly hard (15.4 doH) and well water from Adice - very hard (34.7 doH). Alternaria solani spore germination test on the glass was performed in four replications. The assessment was conducted by counting the number of non-geminated spores after 48 h and the results were expressed as the efficacy and processed with Two-way ANOVA. In the tap water, the efficacy of Quadris was 58.9%. The efficacy at the same level of significance was achieved with the following mixtures: Quadris + Cipkord 20-EC, Quadris + Actara 25-WG, Quadris + Silwet L-77, Quadris + Cipkord 20-EC + M+ + Quadris + Actara 25-WG + M+ and Quadris + Cipkord-20 EC + Silwet L-77. However, mixtures Quadris + Actara 25-WG + Silwet L-77 (77.7%) and Quadris + M+ (76.2%) achieved significantly higher efficacy compared to the product Quadris alone. The efficacy of Quadris in well water was 73.5%. The efficacy at the same level of significance was achieved in all other variants which contained this fungicide (Quadris + Cipkord 20 EC, Quadris + Actara 25-WG, Quadris + Sillwet L-77, Quadris + Cipkord 20-EC + M+, Quadris + Actara 25-WG + M+, Quadris + Cipkord 20-EC + Sillwet L-77 + Quadris and Actara 25 + WG-Sillwet L-77), excluding Quadris + M+. The efficacy of this spray liquid was 81.7% and was at significantly higher level than other mixtures containing Quadris, thus it may be concluded that only M+ component synergized the effect of single fungicide compared to other variants. According to the results, the effect of Quadris on A. solani depended on the water quality and the mixture components.