The occurrence of new aquatic weed genotypes belonging to the Egeria genus led to the development of this work, aimed to evaluate the behavior of different accesses of E. densa and E. najas in response to treatment with the herbicides diquat and fluridone. Accesses of different E. densa biotypes from Jupiá, Nova, Avanhandava, Promissão and Salto Grande reservoirs and of different E. najas biotypes from Jupia, Três irmãos, Ilha Solteira and Ibitinga reservoirs were evaluated. The experiment was arranged in a randomized complete design with five replications. The treatments and concentrations used in the E. densa and E. najas studies were: diquat (Reward 240 g L-1) at 0.5 and 1.0 mg L-1 with reapplication 12 days after the first application, with fluridone concentration maintained between 3 and 20 mg L-1, and a control without herbicide application. Both species were efficiently controlled by one or two applications of diquat, with both concentrations being efficient; however, the accesses studied presented a differentiated response to the herbicide concentrations. The species and accesses studied also behaved in a differentiated way in response to fluridone action, with medium to highly susceptible accesses occurring in both species.
aquatic plant; weeds; biotype; Hydrocaritaceae; chemical control
