potatoes

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Preventing fungicide resistance in
Rhizoctonia management in potatoes
RHIZOCTONIA MANAGEMENT IN POTATOES RELIES ON CAREFUL USE OF FUNGICIDES TO ENSURE
THAT THE DISEASE IS SUPPRESSED WITHOUT RESISTANCE BEING ALLOWED TO BUILD. A NEW
PRODUCT HAS BEEN DEVELOPED WHICH PROVIDES A NEW CHEMICAL ROTATION OPTION,
ENSURING A MORE SUSTAINABLE DISEASE MANAGEMENT PLAN.
Rhizoctonia solani or ‘Black
scurf’ is a destructive
fungus that can cause
devastating losses of potato
yield. It can be initiated by
both seed borne and soil
borne infection and thrives in
conditions of cool temperature,
high soil moisture and neutral
to acid soil. Although it is not
possible to completely control
Rhizoctonia, by following an
integrated disease management
plan it can be successfully
managed. One of the major
difficulties that growers face
in implementing such a plan
is that of preventing strains of
this disease from developing
resistance to the available
chemicals.
New solution
While other registered fungicide
products work well to combat
Rhizoctonia, growers should
not rely on only one product,
as doing so is likely to result in
resistant strains of Rhizoctonia
becoming prevalent on
their property. To assist in
management of resistance, a
new product has been released.
Emesto® Prime, from Bayer
CropScience, belongs to a
different chemical group and
has a different mode of action,
making it the perfect partner
to other registered fungicides
as part of a sustainable
Rhizoctonia management plan.
Bayer Representative Alistair
Beyer explained how the new
product differs from other
fungicides on the market.
“The active ingredient in
Emesto Prime is a chemical
called penflufen, which is a
Group 7 chemical.
“Continued use of just one
product isn’t sustainable,
but switching between the
different chemistry groups
for Rhizoctonia management
is a much more sustainable
practice. This product offers
that option,” Mr Beyer said.
Rhizoctonia acts by restricting
the ability of the potato plant’s
roots to utilise nutrients and
water from the soil, preventing
the plant from growing healthy
tubers. Emesto Prime is a
liquid product that is sprayed
directly onto and around the
seed tubers during the planting
stage. If Rhizoctonia infection is
present in the soil, the product
provides protection against
the disease infecting the roots
while they establish. It does not
provide protection against tuber
borne disease.
“The product isn’t very
mobile; and doesn’t move very
far,” Mr Beyer said.
“That’s a good thing because
the Rhizoctonia is coming from
the soil around the tuber, so if
you can keep the product in that
location rather than it leaching
away from the tuber or moving
up into the plant, it will protect
the roots of the seed potato.”
Peace of mind
Emesto Prime provides
comprehensive control of soil
borne Rhizoctonia, acting on all
of the key strains of the disease
that affect potato production in
Australia. Mr Beyer reassured
growers that they do not need to
worry about which strain of the
disease they might have.
“It provides peace of mind
that if you use this product,
it doesn’t matter which strain
you’ve got, you’ll be able to
effectively manage it.”
Although the new product
is effective, it is strongest
when used in rotation with
a fungicide belonging to a
different chemical group,
such as Group 11 fungicides.
Overuse of any chemical group
is likely to result in high levels of
fungicide resistance in disease
populations. Mr Beyer stressed
that chemical rotation will ensure
successful management of
Rhizoctonia and allow growers
to use the same chemicals for
longer.
“There’s some good chemistry
out there already, but it’s not
sustainable to continuously
use one product. There are not
many management tools for
Rhizoctonia in potatoes, and
Emesto Prime provides another
option. Rotating other registered
fungicide with Emesto Prime
makes a lot of agronomic sense.”
i
For more information,
please visit
www.bayercropscience.
com.au
Emesto® is a Registered
Trademark of the Bayer
Group.