Search for a herbicide suitable for controlling submerged aquatic weeds under Indian condition

It was observed that glyphosate and different types of 2,4-D which are being used extensively for controlling floating aquatic weeds could not produce any significant effect on any of the test weeds even at higher than the recommended doses. Fluridone, a new systemic herbicide, worked well in controlling rooted submerged aquatic weeds. Experiment was conducted under indoor condition for 90 days and tested at different doses from 0 to 90 μgL⁻¹ on three rooted submerged weeds i.e. Vallisneria, Najas, Hydrilla and one non-rooted weed i.e. Ceratophyllum. Fingerlings of rohu were released at higher doses of fluridone (30 to 90 μgL⁻¹). Herbicidal symptoms of fluridone appeared within seven days and slowly killed the rooted submerged weeds over 45 to 90 days. Because of this, it didn't pollute the environment and fish didn't suffer from oxygen deficiency. Efficacy of fluridone in controlling four tested submerged weeds was of this order: Najas > Hydrilla = Vallisneria > Ceratophyllum. Analysis of blood biochemical parameters of fish revealed that fluridone had no toxic effect on fish at the doses in which it killed the weeds. Presently management of aquatic ecosystem is the only option to control submerged weeds as herbicides available in India are not effective on submerged aquatic weeds. Fluridone has the potentiality to be an ideal herbicide to solve the problem of submerged aquatic weeds in India.