16-001014-02A (Ultimate SCMMP)

Emergent
Emergent aquatic plants are rooted in the substrate and
have their stem, leaves, and flowers protruding above
the water surface. Emergent plants grow in water depths
ranging from +0.1 m to -0.7 m and are generally well
adapted to regular drying and wetting phases
throughout the year.

Individual or small clumps of emergent plants can be
controlled using physical removal methods, such as hand
pulling, raking, or grubbing. Many emergent weeds have
rhizomatous root systems and care must be taken to
ensure that the entire root system is completely
removed, as it is possible for the plant to re-establish
from the remaining root fragments.

Mechanical harvesters can also be used for temporary
control; however, emergent weeds such as Alligator
weed reproduce vegetatively from stem fragmentation
and disturbance to the floating or emergent foliage may
inadvertently help to spread the weed to adjoining areas.

Emergent plants such as Cumbungi can be effectively
controlled by cutting the stems below the water surface.
This removes the oxygen supply to the roots, resulting
in anaerobic respiration and ultimately the death of the
plant.

The use of appropriate, non-residual herbicides is also
an effective control method for emergent plants,
particularly where large isolated clumps may have
developed within sediment basins or constructed
wetlands.

Herbicides may be directly applied to individual plants
using rope-wick applicators or hand applied using a
sponge and rubber gloves. Foliar application of
herbicides is generally more appropriate for controlling
large clumps of emergent weeds. Care must be taken
to ensure that the herbicide is directed onto the weed
foliage and that any adjacent open water areas or
non-target plants are avoided.




                                                            Maintaining Vegetated Stormwater Assets Version 1   61