MAPPING THE RESISTANCE OF SPECIES OF THE GENUS Amaranthus IN SOYBEAN PRODUCTION AREAS
resistance; chemical control; caruru
Periodic monitoring of the dispersal of weed species is one of the ways to prevent the spread of resistant biotypes. As is the case of caruru, with several species reported as resistant to the herbicide glyphosate, which has made its management difficult in the field. The objective of this work is to map the dispersion of glyphosate resistant caruru populations, propose management alternatives, identify and characterize the different resistant species found in soybean producing areas in Brazil. The experiments will be conducted at the Federal Rural University of Rio de Janeiro – Seropédica/RJ, in a greenhouse in the experimental area of the research group on Weeds and Pesticides in the Environment - PDPA. The samples of caruru seeds will be collected by the company in the field by partners, in areas with escapes from the application of the glyphosate herbicide. The first experiment will be conducted with all biotypes collected in the field, in a stage of 6 fully expanded leaves. The herbicide glyphosate (2.5L ha-1) will be applied for a first screening of herbicide survival. From the surviving biotypes, seeds will be collected for the next generation (F2). With these biotypes, a dose-response curve test will be performed, always in comparison with a known susceptible control of the same species, where the treatments will be the doses of the herbicide glyphosate: 6D, 4D, 2D, D, 1/2D, 1/4D 1/6D and witness without application. Dose D corresponds to 2.5L ha-1 of glyphosate herbicide. With these biotypes, an assay will be conducted with the following herbicides: cloransulam (47.6g ha-1), chlorimuron (20g ha-1), bentazone (1.2L ha-1), flumioxazin (100g ha-1), diclosulam (41 ,7g ha-1), to evaluate possible alternatives for their control in the field. Of all the biotypes used in the research with resistance to glyphosate, the description and anatomical characterization of the species will be made and the production of specimens documenting the variability of the plants as well as the regions (plotted on a map) of the materials studied in the research.