Home' Grower : October 2012 Contents The South Australian Grower -- October 2012
Synthetic chemical toxicity
can disrupt endocrine systems
THE growing body of published science
on endocrine disruption, where very
small amounts of some synthetic
chemicals can act like hormones, has
many scientists stating that methods of
assessing the toxicity of synthetic
chemicals in our diet and environment
The model of toxicology (science of
poisons) works on the notion that the
lower the dose the less the effect of the
When animal testing shows that a
certain dose level of poison causes no
observable ill effects, this dose becomes
the basis that is used to determine the
average daily intake .
Authorities then claim that any residue
levels below the ADI are too low to cause
This model is based on the assumption
of a monotonic dose response in that the
toxic effect decreases in a steady linear
progression until the compound is no
It comes from the maxim of Paracelsus,
the 16th century physician and father of
toxicology, who stated that 'all things are
poison and nothing is without poison.
only the dose makes a thing not a
poison.' This has been condensed to:
'The dose makes the poison'.
There are numerous exceptions to this
assumption, however, one of the most
profound is the evidence of
nonmonotonic responses in many
chemicals when they start to act as
hormones at very low levels.
The most significant meta study on this
was published in March by several of the
world's leading expert scientists in this
field in the peer-reviewed journal
The scientists stated: "We illustrate that
nonmonotonic responses and low-dose
effects are remarkably common in
studies of natural hormones and EDCs.
Whether low doses of EDCs influence
certain human disorders is no longer
conjecture, because epidemiological
studies show that environmental
exposures to EDCs are associated with
human diseases and disabilities. We
conclude that when nonmonotonic dose-
response curves occur, the effects of low
doses cannot be predicted by the effects
observed at high doses."
The endocrine system is based on
numerous hormones that regulate the
normal functioning and cycles of all living
species, including humans. In the 1940s,
scientists began to notice that some
pesticides produced hormonal changes in
By the 1980s, there were numerous
studies showing that many chemicals,
including pesticides were causing
significant hormonal changes in living
species, especially with the reproductive
As an example, researchers have now
found that there are many chemicals that
act like estrogen and they are causing a
range of reproductive and other problems
in numerous species including humans.
These xeno-estrogens are implicated in
lowering sperm counts, increasing the
number of offspring born with genital-
urinary tract abnormalities and also with
the increase in cancers of the sexual
tissues (breast, ovarian, uterine,
testicular, prostate and vaginal cancers).
Details: The Organic Update is a publica-
tion of the Organic Federation of
Australia, GPO Box 787, Brisbane,
Grower wins virus battle
By TONY BURFIELD
AFTER several years of bat-
tling the damaging cap-
sicum tobamovirus, Sen
Thac seems to have found some
very important answers.
He tested a range of strategies
in three seasons and the findings
have added-up to what looks like
a virus-free crop this season.
Tobamovirus is not spread by
insects, but through human con-
tact, plant-to-plant and by plant
debris or soil with un-decayed
plant debris in it.
Affected plants become highly
risky sources of infection, lead-
ing to high disease rates in close-
ly packed greenhouse crops in
Infected plants have no cure
and fumigation does nothing
against the virus pathogen in the
This virus requires an integrat-
ed strategy to be eliminated.
Strict farm and worker hygiene,
in particular, will prevent its
transfer to plants.
New crops planted in place of
infected ones -- without extended
fallow periods and break crops of
plants not affected by the virus,
such as cucumbers, usually show
higher infection rates.
Virus particles remain in un-
decomposed plant trash from
previous crops and infect roots
of new seedlings that come into
After attending an information
workshop facilitated by
Queensland virologist Denis
Persley in 2009, Mr Thac began
to implement a range of hygiene
and barrier strategies.
These gave some measure of
relief, but crops were never
entirely free of the disease.
Strict worker hygiene, includ-
ing barring workers from being
employed at other farms and
requiring them to change
clothes and shoes between crops
of different ages, has been essen-
Mr Thac is planning to set up
plastic footbaths with 1 per cent
bleach to make it easier to keep
Consistent hygiene practices
are the only way to limit the
spread of the virus, but are not
Mr Thac has been trialing sev-
eral Tobamovirus-resistant cap-
sicum varieties with mixed
The plants seem to suppress, or
block, the disease but not all
produce fruit that suit his mar-
But he has found a variety with
all-round characteristics and only
slightly reduced yield.
Mr Thac first trialed this
among last year's crop and is
now planting it as his main crop.
I inspected the plants with him
the other day and they were in
excellent health. So fingers
The real test will come with the
warm weather, but last year's
success is a pretty good indicator
of how things should turn out.
Growers need to do their own
variety trials and decide for
themselves which meet their
needs and make sure they imple-
ment effective hygiene practices.
As with tomato spotted wilt-
resistant capsicums introduced in
the late 1990s, virus tolerance in
plants can break down and
should not be taken for granted.
Make sure you implement a full
disease prevention strategy.
Mr Thac emphasised the
importance of working together
with experts and other growers,
and not giving up on problems if
you want to win.
Details: Tony Burfield 0401 120 857
Sen Thac emphasised the importance of working together with experts
and other growers, and not giving up on problems if you want to win.
Affected capsicum plants become highly risky sources of infection,
leading to high disease rates in closely packed greenhouse crops in
Corporate Grape producer meets
demands of intensive spray programs
Spray programs on large
Corporate Farms can
involve spraying around
the clock for weeks at a time.
Table grapes require intensive
management during the
growing season, addressing
nutritional requirements and
Some treatments can require
up to 6 spray applications in
one growing season.
is a leading Australian grower
and marketer of fresh produce
supplying fruit and vegetables
to markets all over Australia
Recently, at the St George
complex, vineyard sprayers
have been upgraded with
Arag Spray Controllers.
Arag, an Italian company, are
now a leader in spraying
technology, offering a range of
advanced Spray Rate
Controllers for all agricultural
needs including Horticulture,
Viticulture and even Individual
Nozzle Control on Broad Acre
Because of the intensity and
costs of spray programs on
these large farms, cost
reduction is very important.
Greater efficiencies can be
gained using rate controllers
for all spraying.
Traditionally spraying was
done by monitoring a pressure
gauge, which would equate to
an amount of spray being
discharged at a particular
But when the ground speed
changes, the pressure needs
adjustment to keep the
application per area constant.
It is virtually impossible to
adjust the pressure manually
on the go.
A Spray Rate controller simply
monitors the flow via a Flow
Meter and equates it to the
Ground Speed. It then
automatically adjusts the
pressure to keep the
application rate consistent as
the ground speed changes.
This seems a very simple
process, but it needs to be
done on a 'hostile
environment' for electronics.
The hardware must perform,
be durable, reliable and
simple to use.
Arag leads the field in this
area, with both sprayer fitted
hardware, and cabin mounted
The Arag range of controllers
cover all sprayers from a basic
unit to full Data Logging of
jobs and GPS Mapping.
Paul Fischer from Eldredge Enterprises,
explaining the Arag valve assembly for a Multi
Row Vineyard sprayer, to Dennis Aitkin of
CostaExchange, St George, Qld.
• For further details, contact Australian
Distributor, Eldredge Enterprises on
Ph 08 8842 1256,
website: www.eldredge.net.au and visit
the Arag website at www.aragnet.com
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