Controle químico de brilhantina (Pilea microphylla) no cultivo de orquídeas

Abstract

This study aimed to evaluate the efficacy of oxyfluorfen in the control of Pilea microphylla in orchid cultivation. Two experiments were carried out in a randomized block design, arranged in a factorial scheme 2 x 7, with three replicates. One trial was composed by two orchid species (Epidendrum ibaguensis and Dendrobium sp.) and seven oxyfluorfen rates (0.000, 0.024, 0.072, 0.144, 0.216, 0.288 and 0.36 L ha-1 of i.a.), sprayed over the total area and the other was composed by the same species and seven oxyfluorfen concentrations (0.00000, 0.00036, 0.00072, 0.00144, 0.00288, 0.00576 and 0.01152% of i.a.), directly sprayed without reaching the orchid leaves. Each experimental unit was represented by a pot with an orchid plant infested with Pilea microphylla. At 15, 30 and 60 days after application (DAA) visual evaluations of toxicity on orchid and Pilea microphylla control were performed, using a scale from 0 (toxicity absence) to 100 (plant death). No interaction between species and rate or concentration of herbicide and no difference in herbicide behavior or symptoms of toxicity on orchid plants were observed in either experiment. Efficient control of Pilea microphylla was verified for rates superior to 0.26 and 0.25 L ha-1 at 30 and 60 DAA, respectively, in the total area application, and for concentrations superior to 0.0020 and 0.0019%, at 30 and 60 DAA, respectively in direct spray. Oxyfluorfen provided efficient control of Pilea microphylla with spray in total area and direct spray, without harming the orchid plants.