Drift of auxinic herbicides in new transgenic events in different application situations and its efficacy against Conyza bonariensi growth in different environmental conditions

• Grant number: 16/10941-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: November 01, 2016
• End date: October 31, 2017
• Field of knowledge: Agronomical Sciences - Agronomy - Crop Science
• Principal Investigator: Pedro Jacob Christoffoleti
• Grantee: Wilson Geraldo Pereira Neto
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

The auxin herbicides such as dicamba and 2.4D are alternatives in the control of glyphosate resistant biotypes of buva. However, to achieve control efficiency it is important to look at the biological adaptation of weed plants under its environmental conditions, especially characteristics related with leaf structure. Another relevant point is the herbicide potential to cause phytotoxicity through its drift towards adjacent non-resistant crops. In order to minimize the drift risk it is important to use an adequate nozzle and observe the environmental conditions during field application. Thereby, the objective of this study is to investigate the influence of the wind speed and the type of nozzle in the herbicide drift and access its control efficacy in glyphosate resistant biotypes of Conyza bonariensis under different environmental conditions. In the herbicide drift capacity experiment the analysis are going to be performed by a completely randomized design in a factorial system 3 x 4 x 3 with four repetitions. There will be three nozzles (Teejet XR 110.02, Teejet TI 110.02 and Teejet AI 110.02), four different distances from the sprayer (0m, 5m, 10m and 20m) and three the wind speeds (5 km /h, 10 km/h e 20 km/h). This model is going to be applied for each one of the herbicides assessed (2.4 D amina, 2.4 D colina e dicamba) and the experimental unit will be metallic rods placed in three different heights combined with the three wind speeds. The filter paper is going to be collected and analyzed in a spectrophotometer of atomic absorption. The quantity of herbicide collected in each experimental range will be sprayed over tomato plants in three distinctive phenological stages of vegetative growth (flowering and fructification). The evaluation of phytotoxic effects is going to be determined by visual evaluation. In the second experiment it is going to be planted glyphosate resistant biotypes of C. bonariensis (South and Middle West) and susceptible biotypes of C. bonariensis (Southeast). They are going to be kept under phytotron in the respective environmental conditions of each region. The leaf structure is going to be accessed using scanning electron microscopy. The controlling experiment is going to be performed under a completely randomized design in a factorial system 4 x 3 with four different herbicides (dicamba; 2.4D; dicamba + glyphosate and 2.4D + glyphosate) and three populations of weeds (southeast susceptible, south and southeast resistant). The treatments are going to be applied after plant emergence. The controlling is going to be visually accessed in the 7th, 14th, 21th, and in the 28th day after application. In the 28th the dry matter will be determined. The data is going to be analyzed statistically. (AU)