Effect of water quality on physical properties and biological activity of tank mix insecticide-fungicide spray

Abstract

The physical and biological compatibility of plant protection products applied in short succession or in tank mix depends on active materials, formulation and quality of water for spray preparation. During the vegetation season of 1999 small farmers near Novi Sad were obliged to use raw water of poor quality, as the main supply of municipal tap water was destroyed by bombing. The raw water differed in quality by higher pH, hardness and content of NO2 -, Fe2+, Fe3+, NH4 +, Ca2+, organic materials in comparison to drinking tap water and affected the physical traits of spray liquids, ability to tank mix and quality of vegetable protection. The pH of fungicide tank mixed with insecticide suspensions was higher in raw water compared to tap water. Stability of mixtures decreased in tank mix of Pyrinex 48-EC or Sucip 20-EC with either Mankogal-80 or Folpan WP-50, and surface tension decreased, when raw water was used. A possible interaction might exist between tank mix fungicide, insecticide and water mineral content, which influenced its efficacy against Alternaria alternata spore germination and Colorado potato beetle mortality and some tank mixes induced phytotoxicity on tomato. The low quality of raw water restricted the choice of tank mix coupling partners.