©Kondinin Group
Reproduction in whole
or part is not permitted
without permission.
Cropping
Pest control
FreecalL 1800 677 761
Mice numbers
cause cropping
concerns
Producers worried about being able to get machinery onto wet country to
sow winter crops now have the extra burden of mice eating seed before
it germinates, reports Kondinin Group’s Pamela Lawson.
D
Hunger holes: Evidence of mice damage is very
visual in this early stage wheat crop, with holes
dug at every plant by mice looking for seed.
Photo: Luke Nettle
Inset: Mice numbers are set to explode following
the favourable seasonal conditions recently
experienced in the eastern and southern grain
belts of Australia.
Photo: GRDC
At a glance
Ideal conditions over spring and
summer mean mice damage could
threaten crop germination.
Producers should be vigilant in
monitoring mouse numbers and
use management options to
minimise the scourge.
There are a limited number of
rodenticides available for use in
and around crops to control large
mouse populations.
All baiting must be carried
out under strict conditions,
with advice sought from local
authorities.
Conditions since last spring
have been ideal for the
growing plague.
What to look for
Over summer, while there has been ample
food in stubble paddocks for mice to feed
on, population size may not be obvious.
But as the weather cools and stubble
burning begins, mice relocate to other areas
in search of nourishment and become easier
to monitor through the use of traps, tracking
baits and bait stations positioned in
paddocks, around shed and along fence
lines.
Monitoring advice and assistance is
available to producers from their local
agronomists. In NSW, additional advice can
be sought from local Livestock Health and
Pest
Authorities
(LHPA)
rangers.
Simple monitoring techniques which
are quick and easy to use are described in
Industry and Investment NSW’s Primefact
505, available at www.dpi.nsw.gov.au, and
the GRDC website also has additional
technical advice at www.grdc.com.au/
pestlinks and www.grdc.com.au/mouse_
management.
Mice increase rapidly with favourable
conditions such as the prolonged availability
of high-quality feed, high crop yields and
poor harvesting efficiency, damaged mature
crops and high weed and native grass levels
following summer rains and heavy crop
residues.
Ripening summer crops have also been
targeted this year, with damage recorded in
rice, sorghum, corn and millet crops in
NSW.
By the time numbers of mice reach plague
dimensions,
control
and
damage
minimisation becomes difficult, so early
detection and action is essential.
Cause for concern
If large mouse populations are left
unchecked in areas where winter crops are
sown, damage will include seed loss
(especially pulse and cereal crop seed) as
mice will follow planted rows and dig up all
the available seed. Crops such as canola will
suffer damage to the emerging first two
leaves or cotyledons resulting in the death of
the plant. As other food sources become
scarce, mice will continue to feed on any
available crops, with damage most severe
for about two to three weeks after crop
emergence and again around seed set. But
significant damage can also occur to tillering
cereals, especially durum wheat, and there
uring 2010, severe mouse damage
on the central and western Eyre
Peninsula in South Australia at
sowing caused average losses during crop
establishment of $20–$40 million, with
average yield losses of 30 per cent in badly
affected crops.
Even at less than plague proportions,
losses Australia-wide from mice eating
crops, stored grain and damaging electrical
wiring could reach and estimated
$100 million a year.
In the lead-up to the 2011 winter crop
sowing season, producers throughout the
grain belts of eastern and southern Australia
have been alarmed at increasing numbers
of common mice evident in grain storage
areas, machinery sheds, houses and
paddocks.
42 Farming Ahead May 2011 No. 232 www.kondiningroup.com.au
Cropping
pest control
are often higher weed control costs in
subsequent years, due to grassy weeds
invading crops significantly thinned by
mice. Mice eat about three grams of grain
per head each day and densities of 200–500
mice per hectare will cause major crop
losses. During 2010 in South Australia, it is
estimated densities of 1000 mice per hectare
were not uncommon.
Management options
Producers can minimise the food available
to mice over autumn by controlling summer
weeds and preventing them setting seed,
especially along fence lines and crop
margins.
Graze stubbles hard and early to remove
left over grain, especially in areas not
harvested, or with high levels of split grain
and encourage birds of prey by erecting
artificial roosting poles.
If mouse numbers are still at damaging
levels as sowing approaches, farmers can
consider slightly increasing sowing rates
and sowing as deeply as appropriate for the
crop to try and reduce the amount of seed
eaten by mice prior to germination.
Sow as early and evenly as possible to
achieve a rapid establishment of strong
plants and try to avoid dry sowing.
Use cross harrows, or rollers after sowing
to ensure good seed coverage and remove
sowing lines.
Farmers using direct drilling and
minimum tillage practices should be aware
there is the potential for these areas to have
larger paddock mouse populations, even in
normal years, due to the lack of habitat
destruction normally caused by ploughing.
If possible, do not direct-drill any crop
(especially lupins) into a paddock where
large amounts of grain were spilt the
previous harvest.
Chemical control
When high mouse populations are already
established at sowing, cultural practices are
often insufficient to control damage, so
baiting may well be necessary.
A survey by Biosecurity South Australia of
140 landholders, who experienced a mouse
plague during 2010, revealed effective
baiting was improved by baiting at, or
immediately after sowing (rather than four
days to a week later).
The use of registered zinc phosphide
products at recommended rates and effective
summer weed control also helped.
Most commercial rodenticides are not
registered for in-crop use as they are usually
anticoagulants, which are costly, slow acting
(resulting in multiple bait uptake) and can
poison dogs, cats, domestic livestock and
other non-target species.
This type of poison is generally restricted
to careful use around sheds and grain
storage facilities.
The poison bromadiolone is a grain-based
anticoagulant bait, but it is registered for
use only as a crop perimeter bait. It can be
used on fence lines, but not within a crop
and will only tolerate light rain and dew.
It can be ordered through local LHPA
offices in NSW and rural suppliers Australiawide and should be mixed only with clean
grain as chaff and dirt will soak up the
poison, but will not be eaten by mice.
Bromadiolone is quite
slow acting and mice will
consume bait for up to three
days before dying.
Photo: Luke Nettle
Zinc Phosphide Bait
Check yo
ur
crop NOW
!
Prevent
Losses,
Treat NO
W!
• Low cost delivers maximum
protection
It can therefore be more labour intensive
and costly to apply as more bait is required
to achieve a significant kill.
Lethal weapon: Dead mice dug up from a single
mouse hole after zinc phosphide bait was applied
to the paddock.
MOUSEOFF
®
In-crop baiting
Zinc phosphide (ZnP) is the only
registered chemical option available for incrop mouse control. It can only be used
under strict instruction and following
sufficient monitoring to ensure mouse
activity levels justify baiting. Strict baiting
criteria have been established to minimise
the risks associated with the release of toxic
phosphine gas when ZnP is used as bait
although the gas is not readily released.
If mouse numbers are particularly high
and quick results are needed, it is a
recognised strategy to use ZnP in the body
of the paddock and bromadiolone around
the perimeters. Further monitoring is
essential after any baiting, although
rebaiting should not occur for 14 days.
Damage from mice will stop overnight but
• Yield protection and harvest income
far outweighs treatment cost
• Rapid kill of mice in crop and field
• Quick and humane control
• Available when you need it: “Now”!
• Use risks are all low
• Stable bait in storage
• At local S7 accredited resellers
Animal Control Technologies
Australia Pty Ltd
Phone: 03 9308 9688 Fax: 03 9308 9622
Email: [email protected]
More info at www.animalcontrol.com.au
Excellence in Pest Animal Management
Farming Ahead May 2011 No. 232 www.kondiningroup.com.au
43
Cropping
pest control
numbers will start to creep back to problem
levels in 5–8 weeks if mice are breeding.
Application methods
Zinc phosphide bait can be spread using
aerial or ground application at a rate of one
kilogram per hectare, which will provide
20,000 lethal doses per hectare.
ZnP baiting will take out a large proportion
(70–90 per cent) of mice in the first day and
all the bait should be gone 2–3 days after it
is applied.
This bait can be spread in stubble, pasture
and crop, or a vegetative fallow, but not on
bare ground. It can not be used around
buildings, in towns or residential areas, on
roadsides, Crown land, or in native
vegetation and must not be laid within 50
metres of the crop perimeter or native
vegetation.
Zinc phosphide will tolerate slightly more
rain than bromadiolone, but as little as five
millimetres can render it useless as the
action of the rain erodes the poison off the
bait.
Rebaiting may be required if rainfall
occurs within the first couple of days of
baiting. Ideally, mouse bait should be used
in dry conditions to achieve maximum
ingestion of the active ingredients.
Record keeping
Producers should keep thorough records
and evidence of monitoring mouse
populations before beginning a baiting
program. These records should include
where the mice are present (for example
crop type, area, refuge facility), what
monitoring method was used (how many
consensus cards, traps or baits were
distributed), where the monitoring
equipment was placed, the results
(percentage of bait taken and number of
mice caught) and the date and time of
monitoring.
Keeping record: Always keep thorough records
when monitoring mouse activity.
Photo: Luke Nettle
Once baiting commences, landholders
are legally obliged by the Pesticides Act 1999
to complete and retain baiting records,
which need to include details such as the
product used, date applied, application
method and rate, the batch number and
withholding period.
Any mouse baits should be
handled, stored and disposed
of strictly according to label
instructions.
Ongoing concern
The usual breeding season for mice in
dryland crops in southern Australia is
October to May, with population at their
lowest in late winter when food is scarce.
But if feed is available for longer and
population numbers do not decline in late
winter, a second period of high crop damage
could occur during crop flowering and seed
set in some areas.
Grain Aeration Protects
your Profits
Looking beyond this season, the costs of
mouse damage in grain cropping areas is
likely to rise as long as no-till, continuouscropping, livestock-free farm systems
became more prevalent, along with more
extreme weather events.
According to Biosecurity SA’s natural
resource management biosecurity senior
research officer, Greg Mutze, reduced
competition from livestock grazing in grain
stubbles, more frequent cropping, stubble
and trash retention and more diverse crops
will continue to increase the amount of
grain available to mice.
This will also increase the time span over
which high quality food is available, the
amount of cover and prolong the period
crops are vulnerable to damage from mice.
“Mouse numbers are now higher for any
set of seasonal conditions and are reaching
problematic levels more often than
previously recorded, and are causing more
damage for any given level of mouse
infestation,” Greg said.
“More cost-effective baiting options may
be able to address part of the problem, but at
the core of the issue was the quantity of seed
left in stubbles.
“Grain loss at harvest is the main
determinant
of
subsequent
mouse
infestation and damage in autumn, and the
extent of grain loss in harvesting bumper
crops appears to be underestimated by many
producers.”
Acknowledgements
David Croft, 1080 Consulting,
Greg Mutze, Biosecurity SA,
Trent Fordham, Hume LHPA,
Luke Nettle, Eyre Peninsula Natural Resources
Management Board.
Contact Pamela Lawson
[email protected]
Australia’s most
versatile grain conveyor
Take the guesswork
out of protecting
your grain!
Fan, Duct and Controller
Systems to suit all
grain storages.
WALINGA AGRI-VAC delivers:
GRAINSAFE 3000 Aeration Controller
(with drying mode option)
Store grain longer
Avoid hot spots
Manage insect activity
Prevent mould and sprouting
Suits most existing storages
Designed for Australian conditions
Protects seed germination
Allows early harvest.
Freecall 1800 242 699
Health & Safety – no
dangerous moving parts
Cost savings – full use of
existing & tempory storage
Versatility – suck & blow
grain up into silos & difficult
locations
[email protected] www.customvac.com.au
44 Farming Ahead May 2011 No. 232 www.kondiningroup.com.au
Capacity – models to
suit your needs, up to 100tph
Reliability – proven
performance in Australia
since 1983.
DMS/CVAC-2723B