16-001014-02A (Ultimate SCMMP)

                                                                     Integrated control strategies that combine
                                                                     both physical and chemical removal
                                                                     techniques have proven to be effective at
                                                                     controlling water hyacinth infestations.

                                                                     The integrated use of two introduced weevil
                                                                     species (Neochetina eichhorniae and
                                                                     Neochetina bruchi) has proved to be effective
                                                                     in the control of large water hyacinth
                                                                     infestations.

                                                                     Two moth species (Niphograpta albiguttalis
                                                                     and Xubida infusella) have also been
                                                                     introduced; however, they have not been as
                                                                     successful as the weevils at controlling water
                                                                     hyacinth populations.




                                                                     Water lettuce (Pistia stratiotes)

                                                                     Free floating perennial aquatic plant with
                                                                     ribbed, spongy, velvety leaves that overlap to
                                                                     form a rosette that resembles a small lettuce.
                                                                     The plant extends to 20 cm above water level
                                                                     and has feathery roots up to 80 cm. The
                                                                     leaves are strongly water repellent due to
                                                                     hairs on the surface.

                                                                     Flowering: January–March, but will vary with
                                                                     location
     Photo: Jason Sonneman, DesignFlow
                                                                     Reproduction: Seed and by vegetative
                                                                     daughter plants on the end of stolons

                                                                     Control: Physical removal, chemical,
                                                                     biological

                                                                     Two introduced weevil species
                                                                     (Neohydromonus pulchellus and Orchetina
                                                                     bruchi) have been used successfully to control
                                                                     large infestations; however, effective control
                                                                     by these weevils may take years to achieve.




66                            Maintaining Vegetated Stormwater Assets Version 1