Droplet size and silicon surfactant on spray deposition and weed control

• Grant number: 17/02492-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2017
• End date: July 31, 2018
• Field of knowledge: Agronomical Sciences - Agronomy - Plant Health
• Principal Investigator: Evandro Pereira Prado
• Grantee: Agatha da Silva Argioli
• Host Institution: Faculdade de Ciências Agrárias e Tecnológicas. Universidade Estadual Paulista (UNESP). Campus de Dracena. Dracena , SP, Brazil

Abstract

The maximization of control efficiency and lower environmental contamination is the greatest challenge involved pesticide application. The work aims to verify how the droplets size and silicon surfactant (SS) may affect spray deposition and weed control efficiency. To measure the effects of spray deposition (experiment 1) as a function of different droplet size (fine, medium and coarse) with a 0.1% v/v SS a Brilliant Blue dye at concentration of 1.5 g L-1 will be applied on two weeds species (broad leaf and narrow leaf). The deposition values in mL g-1 dry matter will be submitted to analysis of variance and means comparison by LSD test (p <0.05). For uniformity deposition analysis, the data will be adjusted to regression analysis by Gompertz model. The performance of glyphosate with and without SS, sprayed by different drop size (fine, medium and coarse) on two weeds species will be determined by the weight of fresh and dry biomass 21 days after application. The herbicide will be applied at 1; 1/2; 1/4 1/8; 1/16; 1/32 and 0 (control) of the field lowest recommended dose. With the data the dose-response curves will be elaborated using the log-logistic model: Y =(D-C)/(1+expa{b[loga(X)-loga(C50)]})+C, calculated by statistical model through the SAS program. For better data exploration, will be calculated the parameter R that indicates the ratio of the doses for herbicide alone and herbicide accompanied by SS that give the same effect (Ra) and the ratio of herbicide doses sprayed with fine drops and herbicides sprayed with medium and coarse drops that give the same effect (Rg). (AU)