Efeitos de diferentes condições de umidade do solo e profundidades de germinação de Brachiaria plantaginea e Digitaria spp. sobre a eficácia do herbicida amicarbazone

Abstract

An experiment was conducted in green house, with the objective of evaluating the efficacy of amicarbazone herbicide in controlling Brachiaria plantaginea and Digitaria spp., in function of germination depth and soil humidity conditions. Treatments were constituted by five germination depths of weeds (1; 2; 3; 4 e 5 cm) and four humidity conditions (15 mm of rainfall followed by herbicide application; 15 mm of rainfall, followed by herbicide application and 15 mm of rainfall after 7 days after application (DAA); 15 mm of rainfall, followed by herbicide application and 15 mm of rainfall at 14 days after application (DAA); herbicide application on dry soil and 15 mm of rainfall at 14 DAA, and check without herbicide application, disposed in factorial scheme 5 x 5, with four replications. Weeds seeds were seeded in vases in different depths of germination and visual evaluations of plants control were conducted at 14, 28 and 42 days after application (DAA). It was observed that for B. plantaginea, the best control results occurred in treatments with rains occurrence, being observed initials flaws in controlling when the product was applied in wet soil and without rains occurrence in 1, 2 and 5 cm of depth, with recover and superior control levels at the end of the study. For Digitaria spp., satisfactory levels of efficacy on weeds control were observed in the different application conditions.