Rainfastness effect on fungicide-adjuvant interaction in soybean crop

• Grant number: 21/06510-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: October 01, 2021
• End date: September 30, 2022
• Field of knowledge: Agronomical Sciences - Agronomy - Plant Health
• Principal Investigator: Carlos Gilberto Raetano
• Grantee: Julia Carpin Ariozo
• Host Institution: Faculdade de Ciências Agronômicas (FCA). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil

Abstract

Protective fungicides with multisite action such as mancozeb and copper oxychloride are increasingly used in the prevention of soybean diseases as they provide a low risk of resistance. However, these fungicides may be susceptible to removal by rainwater, a process known as rain fastness. To minimize this problem, adjuvants have been added to the spray solution to increase the contact surface of the active ingredient and the adhesion of the solution to the leaf surface, thus reducing fungicide removal. However, little is known about the role of adjuvants in the surface-fungicide-adjuvant interaction. Thus, the objective of this work will be to evaluate the effect of the association of vegetable and mineral oils on the tenacity of multisite fungicides mancozeb and copper oxychloride in soybean leaves. The experiment will be carried out in a greenhouse, with controlled temperature and relative humidity. The experimental design will be completely randomized in a 6 x 5 factorial scheme, with six spraying solutions and five times of rain. The mancozeb and copper oxychloride fungicide solutions will be applied by a spray system with controlled speed and pressure in an environment with temperature control. After application, each treatment will be subjected to rainfall simulation in the interval of 30, 90, 180, 360 min. and without rain, under 10 mm water depths. The quantification of manganese and copper concentration of fungicides will be carried out by flame spectrophotometry and relating it to the leaf area. The data will be subjected to analysis of variance and, when significant, the mean values of the treatments will be compared to each other. (AU)