Much less effort is required to eradicate a weed when it is just starting to
invade than later when it has become common. One of the most frequent
mistakes is to ignore new weeds until they have reached large numbers.
When a weed is already common it is tempting to try to tackle the worst
places first and to try to get the whole job done in one go. This is a
mistake. Large weeds are harder to dig out or kill, it creates a large area
Work from the least weedy places in to the most weedy 

of disturbance and there will be many weed seeds or fragments left.

Heavily infested areas usually quickly revert to being weedy if follow-up
is postponed, undoing all the original work. Highest priority should go
to maintaining places that are in best condition. Remove outlying weeds
before they can reproduce and then work on the large clumps. This way
the natural regeneration or replanting of native species can keep up
with the clearing.

 

Other reasons for not attempting complete removal of large weed
infestations in one go are the effects on bank stability and on habitat for
native wildlife. Weeds may be stabilising banks, providing shade to the
creek, or providing cover for birds and other animals. Sudden removal
of weeds on a large scale may cause considerable harm, although the
replacement native vegetation will be better in the end. A gradual
process is often preferable. Where weeds are growing in a slow-flowing
creek, killing large amounts at once may make the water deoxygenated
and foul as the dead weeds rot away.

If weed problems are very large or difficult to control it may be best to
simply contain them so they don’t spread any further. This can consist of
a low level of effort to remove new plants outside the infested area and,
for some species, slashing to prevent seed production. When weeds
already dominate the whole riparian zone and resources are limited,
another option may be to create just small weed free patches. These
patches can be a starting point for replanting or natural regeneration of
native species. Information on revegetation of riparian zones is available
from several sources.

 

To help in planning weed control Table 6 contains information on
characteristics of selected riparian weeds and recommended techniques.
The information is simplified and the following should be remembered
when reading it. Effects on stock are difficult to summarise. Even
desirable pasture species can cause problems if suddenly fed in large
amounts. Many weeds sometimes cause illness in stock but usually
don’t, either because the stock avoid eating them or because the amount
available is too small. If lack of alternative food and/or a sudden
increase in availability occurs, these weeds may become harmful.

The column on dispersal and seed persistence is based on best available
knowledge and indicates the most common situation. Downstream
dispersal of seeds or plant parts is an issue with all riparian weeds and is
one reason why a coordinated approach with neighbours is important.
There is often a lack of information on how long seeds remain viable,
which is why no time is shown for some species.