Ten-fold enhancement of 2,4-D effect on water hyacinth by addition of gibberellic acid.

Under greenhouse conditions the effective concentration of 2,4-D (amine salt) for killing water hyacinths could be decreased 10 times if 2,k4-D was applied in combination with extremely low concentrations of gibberellic acid (6 g/ha or higher). This implies that in practice the risk of harming nearby vegetation is considerably reduced, and the cost of spraying programmes might be decreased.