Misturas de produtos em tanque influenciam o desempenho das aplicações fitossanitárias?

Abstract

Mixtures practiced mixtures of chemical products in sprayer tanks hinder the correct positioning of application technology and cause incompatibilities between molecules. This work aimed to study tank mixtures, their physicochemical characteristics, spray droplet spectra and absorption of applied fungicide, in order to verify the impacts on application efficiency and disease control efficacy. The research was divided into three parts involving the soybean crop, in which fungicide and herbicide grouts plus adjuvants and foliar fertilizers were studied. We carried out visual tests of physical stability; pH, electrical conductivity and surface tension analysis; droplet spectrum analysis, using a laser particle analyzer; fungicide absorption evaluation by gas chromatography; evaluation of droplet deposition and losses to the soil, using a dye marker; and disease control efficacy evaluation, using a diagrammatic scale and yield attributes. A CO2 pressurized sprayer was used, TT110015 spray tips, application rate of 160 L ha-1 and working speed of 3.6 km h-1. In the first part of the research, physicochemical studies were performed with fungicide grouts (azoxystrobin + cyproconazole; trifloxystrobin + prothioconazole + bixafen; and mancozeb) in mixtures with glyphosate (potassium salt, ammonium salt and isopropylamine salt), adjuvants (mineral oil, propionic acid and orange oil) and foliar fertilizers (Mn chloride, Mn chelated in EDTA and Mn chelated in citric acid), and with glyphosate plus the same adjuvants or Mn. In the second part, besides physicochemical studies, droplet spectra and absorption of the fungicide azoxystrobin by soybean leaves were also evaluated using the following treatments: 1. azoxystrobin; 2. azoxystrobin + glyphosate; 3. azoxystrobin + mineral oil; 4. azoxystrobin + propionic acid; 5. azoxystrobin + orange oil. In these first two parts, the experiments were conducted in an entirely randomized design. In the third part of the research, the treatments from the previous part were repeated in order to evaluate management of end-of-cycle diseases (OFDs) of soybeans, with experiments conducted in duplicate in a randomized block design, on early and mid-cycle varieties. Only mancozeb was incompatible with glyphosate and Mn chloride. Glyphosate sources were incompatible with Mn chloride. Fungicide grouts tended toward neutral and alkaline pH ranges. Glyphosate, propionic acid, and Mn in citric acid were acidifying agents. Acidic grouts presented higher electrical conductivity. Adjuvants reduced surface tension. The sprays were classified with medium droplet spectrum. The azoxystrobin + glyphosate mixture was the most prone to drift losses and reduced fungicide uptake, which was increased in the grouts with adjuvants. The addition of mineral oil increased grout deposition, but did not prevent losses to the soil. The application of azoxystrobin was effective in managing OFDs. Mixing glyphosate with azoxystrobin is not recommended. Although the compositions of the products determine the physicochemical properties of the grouts, this does not explain their compatibilities in isolation. Tank mixtures affect the performance attributes studied about phytosanitary applications.