Two experiments were carried out to evaluate the effect of rain at different periods of time after glyphosate application, one with Eichhornia crassipes and the other with Pistia stratiotes, both arranged in a randomized design with four replications. The treatments consisted of simulating a 12 mm rainfall for five minutes, at different periods of time (0h, 2h, 4h, 6h, 12h, 24h, and no rain simulation) after glyphosate application at a dose of 2,160 g a.e. ha-1 (4.5 L c.p. ha-1 Rodeo formulation) + 0.5% v/v aterbane. Visual evaluations of weed control at 7, 14, 21, and 28 days after application (DAA) were conducted. The increase in time without rainfall after glyphosate application provided an excellent control for the two species studied and the treatment without rainfall. The occurrence of rainfall after two hours of glyphosate application effectively controlled E. crassipes plants after 14 DAA and P. stratiotes after only 21 DAA. Treatments with rainfall immediately after herbicide application showed a good control for the two species of aquatic weeds only at 28 DAA.
hyacinth plant; water lettuce; herbicide; aquatic plant; weed
