| Ragwort
Senecio jacobea.
Family: Asteraceae
Growth Habit: Ragwort in its first year appears as a flat rosette
of deep green wavy leaves. The bases of these leaves are typically purplish
in colour. At the flowering stage, the leaves of the rosette die off to
be replaced by an upright bush with deeply lobed leaves. The bush can
grow from .5m to 2m in height depending on growing conditions.
Type of plant: Herbaceous biennial. Plants usually flower in their
second year and then die. Control methods that damage the plant but do
not kill it tend to encourage the plant to become a perennial which will
flower in successive years.
Flowers: Large heads of yellow, daisy like flowers in spring,
early summer.
Fruit/Seed: Small seeds are attached to a feathery pappus.
Dispersal: The small seeds can be dispersed as contaminants on
animal coats, in soil on vehicles and machinery and in hay. Although the
pappus attached to the seed can allow the seed to be blown up to a kilometre
or more, most wind dispersed seed falls within 20 metres of the parent
plant. The seeds are often carried by water along drainage lines.
Distribution: Ragwort is widely distributed through out the grazing
areas of Tasmania, although its spread in some areas seems to have been
limited by low rain fall and sheep grazing.
Status: Ragwort is a Declared Secondary Weed. Where possible land
holders must eliminate infestations. In areas where this is not practicable,
land holders have a responsibility to contain and reduce infestations.
Weed Impact:
- Ragwort causes significant loss of pasture production. Once established
it is extremely competitive with pasture species. When plants die off
after flowering they leave bare patches that can be colonised by other
weeds.
- Ragwort is poisonous to all types of stock although older sheep and
some breeds of sheep are less affected. Most grazing animals avoid eating
the plant unless there is a shortage of green feed. However dead and
dried Ragwort plants are very attractive to cattle and horses and poisoning
can occur when it contaminates hay or silage. Single animals may become
addicted to Ragwort and search it out resulting in poisoning and death.
Similar Plants: Fireweed is another member of the Senecio family.
It differs by having smaller yellow flowers and having longer strap like
leaves.
Ragwort - Control Methods
| Control: |
Time applicable: |
Notes: |
| GRAZING |
MAY - DEC |
(a) Sheep can be used to graze and suppress ragwort; however
the plant is toxic and sheep should not graze for more than two
seasons on ragwort.
|
| CULTIVATION |
ALL YEAR ROUND |
|
| PULLING |
JAN - MAR |
(b) With both hand pulling and grubbing, you must ensure the
whold crown of the plants is taken from the ground. Where plants
are flowering, these should be collected and burnt as seeds can
develop from these plants even after they have been pulled from
the ground.
|
| GRUBBING |
JULY - MAR |
(b) |
| SLASHING |
DEC - MAR |
(c) Slashing is only a temporary measure to delay flowering.
It will not control ragwort.
|
| GRANULES |
APRIL - JAN |
(e) For the use of herbicides applied by boom spraying, spot
spraying, wiping or granular application, refer to the Ragwort Declared
Weeds Leaflet. |
| WIPING |
APRIL - JAN |
(e) |
| BOOM SPRAYING |
MAR - OCT |
(e) |
| SPOT SPRAYING |
SEPT - MAR |
(e) |
| BIO CONTROL |
JAN - MAR |
(d) The Ragwort flea beetles (Longitarsus flavicornis
and L. jacobaeae) are showing promise as effective
control means. Spread of the beetle can be increased by collection
of adult beetles over the summer months. At present this is being
done by DPIF staff, but in a few more years this could be done by
landholders.The Cinnabar moth (Tyria jacobaeae) is
also being investigated as a biological control agent.
|
N.B. Always
check the herbicide label before use.
|