Spray deposition and optimizing dosage of herbicides with adjuvants to control Digitaria insularis

• Grant number: 17/00099-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2017
• End date: May 31, 2019
• Field of knowledge: Agronomical Sciences - Agronomy - Plant Health
• Principal Investigator: Evandro Pereira Prado
• Grantee: Arthur Duarte Rodrigues Neto
• Host Institution: Faculdade de Ciências Agrárias e Tecnológicas. Universidade Estadual Paulista (UNESP). Campus de Dracena. Dracena , SP, Brazil

Abstract

Agricultural adjuvant may improve spray retention and increase post-emergence herbicides performance, reducing among of the active ingredient required to have a satisfactory weed control. The aims of this research are (1) to quantify the spray retention capacity by addition of adjuvant on sourgrass plants and (2) to specify the effect of adjuvants on the efficacy of herbicides on sourgrass plants. Spray retention check (experiment 1) of the aqueous solutions with the adjuvants: noni polyethanol, polyether and silicone copolymer, lecithin and propionic acid and mineral oil (0.05, 0.1, 0.5 and 0.5 % v v-1 respectively) will be performed by spraying the solution containing Brilliant Blue dye at the concentration of 1.5 g L-1. The mean retention values in mL g -1 dry matter will be submitted to analysis of variance and the means compared by the LSD test at 5% probability. To verify herbicide dose optimization with adjuvants (experiment 2), will be determined the weight of fresh and dry biomass of sourgrass plants after application of the herbicides cletodim, mesotrione and paraquate (100; 75; 50; 25; 12,5 , 6.25 and 0% of the lowest dose recommended by the manufacturer) isolated and mixture with the adjuvants/concentrations previously described. The response of sourgrass dry and fresh matter to herbicides and herbicides plus adjuvants will be analyzed using a log-logistic model Y =(D-C)/(1+expa{b[loga(X)-loga(C50)]})+C, fitted by the statistic program SAS. For better dates exploration will be calculated the R parameter that indicates the ratio of the doses for herbicide alone and herbicide + adjuvant that give the same effect.