Use of Surfactant With Different Volumes of Fungicide Application in Soybean Culture

Abstract

Application volume, adjuvants that act on the drop surface tension and droplet spectrum are the main factors affecting leaf surface coverage and the spray penetration droplets inside the canopy of the soybean crop, which may have an impact on fungicide efficiency, since those used in the handling of Asian-rust, including those that are absorbed by the plant, present a small displacement from the point of deposition. Thus, it was sought to determine the impacts on the use of the organosilicone surfactant compared to the changes in the spray volumes. For that, five spray volumes and the combination of two adjuvants were compared in randomized blocks with a factorial arrangement 5x2. Reductions in volume negatively impacted the number of drops cm-2 affecting the leaf surface cover which did not exceed 13% in the lower third, in the absence of the surfactant. Also, the reduction in the volume provided decreases in the control of Asian-rust, and the use of surfactant minimized the negative impacts of the disease, reflecting on the index of the leaf area which varied up to 6.5 times on changes in the spray volume, and up to 2.8 times against the use of the surfactant in relation to the mineral oil isolated. Grain yield was negatively affected as reductions in the spray volumes, occurred with less impact when the surfactant was used. Thus, coverage of the leaf surface and the number of drops cm-2 along the plant profile respond to the addition of the surfactant and to the increase of the spray volume, having relation with the control of soybean Asian-rust, and affecting the leaf area index and productivity.

Deposition and Coverage of Soybean Leaf Surfaces by Sprays Applied Using Different Assisted Boom Sprayer Systems

“…The use of the Dropleg ® system had negative impacts on the deposition and leaf coverage in the upper third of the crop in the present study. Application of 65 L ha -1 from the top of the boom and 65 L ha -1 from the flexible rod contributed to reductions in the analyzed variables, especially the leaf coverage, which were related to the volume of the mixture (Roehrig et al, 2018). Thus, it is necessary to vary the ratio between the amounts sprayed at different levels with the Dropleg ® system in relation to those of the conventional spray-boom system.…”

“…Besides using assisted boom sprayer systems, the deposition and coverage of the leaf surface by sprayed chemicals can be maximized by adjusting other factors, such as: the spectrum of the droplets (Silva et al, 2014, Weber et al, 2017França et al, 2018), spray pressure (Cunha et al, 2016), spray nozzle type (Cunha et al, 2014;Madureira et al, 2015;Cunha et al, 2016, Durão & Boller, 2017, adding adjuvants to the spray (Cunha et al, 2014;Madureira et al, 2015;Oliveira et al, 2016), and changing the volume of the mixture (Cunha et al, 2014;Prado et al, 2015;Weber et al, 2017;Roehrig et al, 2018).…”

“…In general, conventional spray techniques using hydraulic or centrifugal nozzles, regardless of the application volume, provide low deposition and coverage in the middle and lower thirds of the plant, especially in plants with high leaf areas like soybean, causing the applied products to have low efficiency (Prado et al, 2015; Engenharia Agrícola, Jaboticabal, v.39, n.2, p.198-207, mar./apr. 2019 Graziano et al, 2017;Roehrig et al, 2018;Müller et al, 2018). This has negative impacts on pest and disease management, as the evolution or development of these problems proceeds from the lower portion of the plant towards the apex, between which the variations in the coverage of the leaf surface by applied pesticides can be as high as twenty-three times (Roehrig et al, 2018).…”

“…2019 Graziano et al, 2017;Roehrig et al, 2018;Müller et al, 2018). This has negative impacts on pest and disease management, as the evolution or development of these problems proceeds from the lower portion of the plant towards the apex, between which the variations in the coverage of the leaf surface by applied pesticides can be as high as twenty-three times (Roehrig et al, 2018).…”

Agronomic and Economic Evaluation of Sequential Spray of Silicon and Fungicides for a Sustainable Soybean Crop

“…There are reports that income losses outweigh 80% under intense infection, depending on the susceptibility of the genotype (Inayati and Yusnawan, 2016). Nowadays the emergence of pathogen populations resistant to the fungicides active principles (Godoy et al, 2016) has demanded the search for new technologies and integrated control measures for a sustainable soybean crop (Furlan et al, 2018;Roehring et al, 2018).…”