2. Weed classifications
Weeds are often classed in broad groups
depending on their characteristics and
impacts. The main groups of weeds are:
◦ Noxious weeds
◦ Environmental weeds
◦ Agricultural weeds
◦ Weeds of National Significance (WONS) and
◦ National Environmental Alert List Weeds.
Many weeds can be classified in more than one
of these groups. For example, blackberry can be
classed as a noxious weed, environmental weed
and agricultural weed, depending on its situation
and is also listed as one of Australia’s Weeds of
National Significance (WONS).
3. Noxious Weeds
Some serious weeds are required by law to be controlled by all
landholders in an area. These are known as noxious weeds and the law
that controls these in NSW is the Noxious Weeds Act 1993.
Weeds that are declared noxious are those weeds that have potential to
cause harm to the community and individuals, can be controlled by
reasonable means and most importantly, have the potential to spread
within an area and to other areas.
A weed is declared noxious because its control will provide a benefit to
the community over and above the cost of implementing control
programs.
Many ‘bad’ weeds do not meet the criteria for declaration. Noxious
weeds will have limited distribution with the potential to become more
widespread and will cause impact on agriculture, human health or the
environment.
In New South Wales the administration of noxious weed control is the
responsibility of the Minister for Primary Industries under the Noxious
Weeds Act 1993. The Act is implemented and enforced by the Local
Control Authority (LCA) for the area, usually local government.
The Act imposes obligations on occupiers of land to control noxious
weeds declared for their area.
There are five classes of noxious weeds identified in the Act (see Table
1). All Noxious Weeds in NSW are listed in the Noxious Weeds
4. Control class Weed type Example control requirements
Class 1
Plants that pose a potentially serious threat to primary
production or the environment and are not present in
the State or are present only to a limited extent.
The plant must be eradicated from the land and the
land must be kept free of the plant.
The weeds are also "notifiable" and a range of
restrictions on their sale and movement exist.
Class 2
Plants that pose a potentially serious threat to primary
production or the environment of a region to which the
order applies and are not present in the region or are
present only to a limited extent.
The plant must be eradicated from the land and the
land must be kept free of the plant.
The weeds are also "notifiable" and a range of
restrictions on their sale and movement exist.
Class 3
Plants that pose a potentially serious threat to primary
production or the environment of a region to which the
order applies, are not widely distributed in the area and
are likely to spread in the area or to another area.
The plant must be fully and continuously suppressed
and destroyed.*
Class 4
Plants that pose a potentially serious threat to primary
production, the environment or human health, are
widely distributed in an area to which the order applies
and are likely to spread in the area or to another area.
The growth and spread of the plant must be controlled
according to the measures specified in a management
plan published by the local control authority.*
Class 5
Plants that are likely, by their sale or the sale of their
seeds or movement within the State or an area of the
State, to spread in the State or outside the State.
There are no requirements to control existing plants of
Class 5 weeds.
However, the weeds are "notifiable" and a range of
restrictions on their sale and movement exists.
NOTE: All Class 1, 2 and 5 weeds are prohibited from sale in NSW.
* In some cases the following wording has also been inserted "the plant may not be sold, propagated or knowingly
distributed."
Table 1 Control classes of noxious weeds
5. Environmental weeds
Environmental weeds are plants that represent a
threat to the conservation values of natural
ecosystems. They invade native plant communities
and out-compete them causing a reduction in plant
diversity and resulting in a loss of habitat for native
animals.
Some examples of environmental weeds are bridal
creeper, bitou bush, boneseed, blackberry and
lantana.
Environmental weeds can also be native Australian
plants that are not local (indigenous) to the area
they are growing in. They have the potential to
displace and out-compete plants within the local
plant community. Examples of native Australian
plants that are doing this are sweet pittosporum and
coast wattle.
6. Agricultural weeds
Agricultural weeds are plants that
represent a threat to agricultural
production. They reduce the area
available for agricultural activities,
interfere with agricultural practices and
affect the quality of produce.
Some examples of agricultural weeds
are serrated tussock, thistles, blue
heliotrope, St John’s wort, Paterson’s
curse and blackberry.
7. Weeds of National
Significance
Under the National Weeds Strategy,
20 introduced plants were identified as
Weeds of National Significance
(WONS).
These weeds are regarded as the
worst weeds in Australia because of
their invasiveness, potential for
spread, and economic and
environmental impacts.
8. The weeds are:
◦ Alligator Weed
◦ Athel pine
◦ Bitou bush /
Boneseed
◦ Blackberry
◦ Bridal creeper
◦ Cabomba
◦ Chilean needle grass
◦ Gorse
◦ Hymenachne
◦ Lantana
◦ Mesquite
◦ Mimosa
◦ Parkinsonia
◦ Parthenium weed
◦ Pond apple
◦ Prickly acacia
◦ Rubber vine
◦ Salvinia
◦ Serrated tussock
◦ Willow
More information: Weeds of National Significance (www.environment.gov.au)
9. National Environmental Alert
List Weeds
Under the National Weeds Strategy,
28 environmental weeds were
identified National Environmental Alert
Weeds. Alert Weeds are non-native
plant species that are in the early
stages of establishment and have the
potential to become a significant threat
to biodiversity if they are not
managed.
24. IPM (Integrated Pest
Management)
IPM is the use of a range of different tools,
equipment and technology to suppress or
eradicated targeted pests.
It can be further broken down to IWM
(Integrated Weed Management) which is
targeted specifically at weeds.
A weed is any plant that is unwanted.
In some situations a plant may be of benefit,
for example: paspalum as a grazing plant.
But in a wheat crop it is a weed.
25. IPM
IPM is broken in to
several groups.
They are:
◦ Cultural control
◦ Mechanical control
◦ Physical control
◦ Biological control
◦ Chemical control
26. Cultural control
Cultural or management control takes in
to account a number of factors which can
influence the establishment and spread
of weeds. Here are some examples:
Using tolerant cultivars in crops.
Crop rotation to break the weed cycle.
Time of planting.
Fertilisers and time of fertilising.
Sanitation, keeping tractors and
machinery clean and free off weed
seeds.
27. Cultural control
This could include
planting competition
plants which are
beneficial.
Applying appropriate
sowing rates and
row spacings.
Grazing land only
back to a certain
level to allow
recovery of wanted
plants.
Crop rotation.
28. Mechanical control
This is using machinery or equipment to
disturb the root zone of the weeds.
For example: ploughing a paddock before
sowing.
29. Mechanical control
These can also
include:
◦ hoeing and chipping
◦ Slashing and cutting
◦ Chaining or
scrubbing
30. Biological control
This is using one
living organism to
control another.
An example of this
is using Lady
beetles to kill
aphids.
Another less
successful
example is using
cane toads to kill
the cane beetle.
32. Chemical control
This is the use of
agricultural
chemicals to kill
targeted weeds.
This is a common
method of control.
However due to the
nature of
chemicals, this
should be the last
option.
33. Physical control
This is using
manual labour to
control weeds.
Examples of this
may be:
◦ Pulling weeds out
by hand
◦ Drainage
◦ Temperature
◦ Light
34. Safety
Like all aspects of agriculture it is important
to consider any safety implications.
Identify the hazards which may arise and
use appropriate measures to eliminate or
reduce the hazard.
Reminder:
◦ The hierachy of risk control
Eliminate
Substitute
Isolate
Mechanical
Administrative
PPE
