Efeitos da aplicação de herbicidas em pré-emergência no crescimento inicial da cultura do melão

The control of weeds in melon crops is hampered by the lack of selective herbicide information for the crop. The objective of this work was to evaluate the effect of pre-emergence herbicide application on two melon cultivars (yellow and christmas melon). Two experiments (one for each cultivar) were carried out in a greenhouse in a completely randomized design, with four replications. The treatments were composed of pre-emergence herbicides: flumioxazin (0.14 l ha-1), ametryn (0.5 l ha-1), sulfrentrazone (0.5 l ha-1), diuron ha-1), metribuzin (0.75 l ha-1), clomazone (0.5 l ha-1), s-metholochlor (1.5 l ha-1), oxyfluorfen (2.0 l ha-1) oxadiazon (3.0 l ha-1) and linuron (1.0 l ha-1); another witness without application. Visual evaluations of phytotoxicity were performed at 7, 14, 21 and 28 days after application (DAA), using percentage scales ranging from 0% to 100%. The leaf number, plant height, leaf area, and total dry matter evaluations were performed at 28 DAA. The results were submitted to analysis of variance by the F test and, in case of significance, the data were compared by the Scott-Knott test at 0.05 probability. For the statistical analysis, the software Sisvar 5.6 was used. The herbicides diuron, ametrina and oxadiazon had a negative influence on the initial growth of the yellow melon. The herbicides metribuzin, diuron and ametrine had a negative influence on the initial growth of the christmas melon melon. The herbicides clomazone and oxyfluorfen did not alter the initial growth of yellow melon and christmas melon melon, presenting great potential for selectivity tests.