L VING ON
Fireweed...
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Fitzgerald Motors
Proudly servicing the Hawkesbury for 65 years
www.fitzgeraldmotors.com.au
46 ISSUE 61 // June 2015
9 Fitzgerald St
Windsor
Phone 4577 3401
The eradication and control of this
weed is the sole responsibility of the
landholder or landowner. This plant
must not be sold, propagated or
knowingly be distributed.
Fireweed is a serious pasture
weed, able to grow on most soil
types. It forms a persistent seed bank
if not controlled before it flowers,
rapidly taking over heavily grazed
and neglected pastures, competing
strongly with existing pasture plants.
It seeds prolifically, each flower
producing between 50 and 120 seeds.
One plant is capable of producing 5
000 to 30 000 seeds in one season.
Fireweed is capable of germinating,
growing and flowering during most
of the year. However, most seeds
germinate in autumn.
Plants grow quickly and can
produce flowers 6–10 weeks after
emergence, with flowering occurring
mainly in spring. Fireweed usually
begins to die off in the spring.
Spread
The light fluffy seeds of fireweed
are spread by wind. This is the main
method of local spread. Most seed
fall within 5 metres of the parent
plant but some seed can be spread
to greater distances in updrafts
and whirlwinds. Dispersal beyond 1
kilometre is more likely to be caused
by unintentional spread by human
activity. Various means of spread
include:
• livestock;
• clothing, vehicles and
machinery; and
• contaminated hay, silage and
grain products;
• as well as spread by wild and
feral animals.
Livestock poisoning
Fireweed contains pyrrolizidine
alkaloids that are toxic to livestock
and cause liver damage. Young
or hungry stock or new stock not
previously exposed to fireweed are
the most at risk of poisoning. All parts
of the plant at all stages of growth
are toxic. Hay, silage or grain that is
contaminated with fireweed plants or
their seeds can also be toxic.
Symptoms of pyrrolizidine
alkaloid poisoning include:
• loss of condition;
• poor growth rates;
• weakness;
• abdominal straining; and
• chronic scouring.
In cattle the most common
problem is ill-thrift, sometimes
accompanied by scouring, weight
loss or failure to gain weight, and
eventually death. Some affected
cattle also develop nervous signs due
to brain damage.
Sudden deaths can occur in fat
animals that are no longer grazing
fireweed-infested pasture but have
grazed them in the previous 3 to 6
months.
Sheep and goats are more
inclined to eat fireweed than cattle
and are up to 20 times more tolerant
of pyrrolizidine alkaloids. Merino
sheep are more tolerant than British
breeds or crossbred sheep because
they restrict their daily intake of the
plant whereas other breeds will eat it
to excess.
If a group of sheep are forced
to eat fireweed over two or more
consecutive years then some of them
may become affected and present
with chronic ill-thrift or sudden death.
Liver damage in sheep and goats
does not usually result in nervous
signs.
Horses are more susceptible to
fireweed poisoning than cattle or
sheep. Affected horses can suffer
brain damage and photosensitisation
affecting un-pigmented areas of
skin. Brain damage results in signs
of dullness, aimless wandering,
an uncoordinated gait, pressing
up against fences, gates or trees,
reduced awareness, and possible
blindness.
Limited evidence suggests that
alpacas are also susceptible to
poisoning.
The liver damage caused
by fireweed is
irreversible and there
is no antidote for
toxic pyrrolizidine
alkaloids. It is difficult
to positively identify
pyrrolizidine alkaloid
poisoning as other
conditions such as
mineral deficiency
and internal parasites
can cause similar
symptoms.
If you suspect that
you have affected
animals contact
your veterinarian to
exclude other possible
causes and to obtain
HAWKESBURY DISTRICT INDEPENDENT NEWS www.hdinews.com.au