Herbicides selectivity on seedlings of White Leadtree (Leucaena leucocephala)

Resumo

Difficulty in controlling weeds has hindered the success of vegetation recovery projects using white leadtree (Leucaena leucocephala) seedlings in degraded areas. The use of herbicides is indispensable to mitigate damage and make these areas viable. Therefore, this study evaluated the selectivity of pre- and postemergence herbi­cides on white leadtree seedlings. Two experiments were carried out in a greenhouse in a randomized block design with four replications. Pre-emergence treatments (g ha^-1) were: atrazine (3,500.00), chlorimuron-ethyl (20.00), clomazone (900.00), flumioxazin (125.00), indaziflam (100.00), isoxaflutole (262.50), pendimethalin (1,150.00), sulfentrazone (500), and S-metolachlor (1,920.00), in addition to a control (without herbicide). The second experiment consisted of the following postemergence treatments (g ha^-1): atrazine (2,500.00), chlorimuron-ethyl (15.00), clomazone (54.00), flumioxazin (20.00), glyphosate (396.25), haloxyfop-methyl (49.88), indaziflam (75.00), isoxaflutole (187.50), pendimethalin (1,150.00), and S-metolachlor (1,440.00), in addition to a control (without herbicide). Phytotoxicity, plant height, and root collar diameter were assessed at 3, 7, 14, 30, and 60 days after application (DAA). Shoot dry matter was assessed at 60 DAA. Herbicides atrazine, indaziflam, and isoxaflutole, applied in pre- and postemergence, in addition to glyphosate, negatively influenced all evaluations, being considered nonselective for white leadtree plants. Herbicides with selectivity, regardless of the application method, were chlorimuron-ethyl, clomazone, flumioxazin, haloxyfop-methyl, pendimethalin, sulfentrazone, and   S-metolachlor.