Evaporação de gotas de caldas contendo fungicidas e adjuvantes depositadas em superfície

Abstract

A necessidade de aumentar a produção agrícola tem como uma de suas ferramentas o uso de agrotóxicos para o controle de doenças, pragas e plantas daninhas. A tecnologia de aplicação visa o uso correto dos agrotóxicos, a fim de maximizar a eficácia das pulverizações e reduzir riscos. Os adjuvantes podem contribuir com a tecnologia de aplicação, pois muitos produtos e têm influência na qualidade e eficiência do processo de pulverização. Em especial, adjuvantes podem interferir no processo de evaporação de gotas no alvo, seja por aumentá-la, por propiciar maior espalhamento, resultando em maior área exposta à evaporação, ou por reduzi-la, já que alguns têm a propriedade de absorver umidade do ambiente e manter as gotas sobre os alvos por mais tempo. Este trabalho teve como objetivo avaliar a evaporação de gotas depositadas em superfície de caldas de fungicidas com adjuvantes, correlacionando este processo com a umidade relativa do ar e a tensão superficial das soluções. Os tratamentos foram compostos por caldas de fungicida isolado (Priori Xtra) e misturados com óleo mineral (Nimbus), organosilicone (Silwet) e óleo vegetal (Óleo Vegetal Nortox). As condições ambientais foram controladas e monitoradas, mantendo-se a temperatura entre 23 e 24 °C durante as avaliações, assim como se variou a...

The need to increase agricultural production has as a tool the use of pesticides to control diseases, pests and weeds. The application technology aims the correct pesticide use, to maximize the spraying efficacy and risks reduction. Adjuvants have contributed with application technology, and influence the droplet evaporation process on target, either by increase it, due increase spreading, resulting in greater area exposed to evaporation, or by reducing evaporation, once some adjuvant can absorb humidity from ambient and keep droplets in target longer. This work aimed to evaluate droplets evaporation of sprau solutions with fungicides and adjuvants on a surface and correlate it with air relative humidity and spray solutions surface tension. The treatments were a fungicide (Priori Xtra) isolated and mixed with tree adjuvants, there are a mineral oil (Nimbus), an organsilicone (Silwet) and a veget oil (Oleo Vegetal Nortox). The temperature and relative humidity were controlled by a heater, an air conditioning, humidifier and a dehumidifier. The temperature during the evaluations was kept between 23 and 24 °C. There was developed a system to capture images, composed by two cameras, positioned perpendicular and lateral to the glass slides where the droplets, 985 μm diameters, were deposited, to evaluate deposition and evaporation. Twelve observations were done between 40 and 80% humidity and developed regression models for those data to characterize evaporation due humidity changes.. Also were done tree repetitions at humidity 45 ± 1% to compare treatments. The surface tension was measured through droplets generated by a capillar, with 3 repetitions for treatment. The treatments averages were compared using Confidence Interval at 5% probability and the correlations between variables were... (Complete abstract click electronic access below)