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Integrated Pest Management (IPM) is a strategy which encourages the reduction of pesticide use by employing a variety of pest control options in combination to contain or manage pests below their economic injury levels. These options include:
IPM aims to maximise the use of biological control. Other control measures, especially chemicals, must play a supportive, rather than a disruptive role. Chemicals should not be used on a 'calendar' basis but strictly when needed as defined by systematic pest monitoring. Selective rather than broad-spectrum chemicals should take preference. The aim is to produce high-quality marketable produce at minimal cost by intelligently using the various control options to manage pests.
Adoption of IPM
For practical purposes, IPM programs can develop through three stages.
STAGE 1
- improved cultural and hygiene practices
- monitoring of pest to reduce pesticide use and achieve better timing of pesticide application
Some crops or situations may be unsuited to Stage 3, but will benefit from stage 1. Stage 3, the highest level of commitment, means investing time and money into encouraging biological agents. A decision to use broad spectrum pesticides in a Stage 3 IPM program cannot be taken lightly, as this may undo the work of the previous months or even years.
- monitoring that also includes beneficial species
- selection of chemicals which are less hazardous to beneficials
- spot spraying and targeted spraying
- selective control of pests with the use of products such as pheromones, Nuclearpolyhedrosos virus, Bacillus thuringiensis, insect growth regulators and baits
STAGE 2
- as for stage 1 and 2, plus
- environmental modification to encourage beneficials
- release of mass-reared beneficials
STAGE 3
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Biological
Control and IPM
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IPM systems consist of
numerous elements with monitoring usually described as the
"cornerstone of IPM". Biological controls, cultural
practices, nutrition and irrigation management are important
elements.
The degree to which
biological control agents (BCA's) can be utilised will vary
from crop to crop and from area to area and will depend on
the answers to a series of questions. For
example:
- Are there effective
natural enemies for the major pests of this crop?
Effective natural controls exist for some pests but not
others.
- Are these mass reared
for introduction or do they enter the crop from local
populations?
This will influence management practices. eg.
conservation of refuge or alternative crops.
- What crops or types of
vegetation are adjacent to the target crop?
Some crops act as refuges for natural enemies while
others can harbour unwanted pests.
- Is the crop being grown
under "organic" or conventional classification?
If the crop is "organic" some low level damage from pests
may be more tolerable.
- Are there "soft"
chemical options for use in conjunction with natural
enemies?
Soft options are available for some pests and not
others.
- Is the crop life span
and environment suitable for natural enemies?
Short lived crops may not be suitable for BCA's.
- Are certain plant life
stages suitable for natural enemies and others not?
BCA's may be useful in early stages of a crop but not
near harvest.
A crop consultant versed in
biological control options will help you answer these
questions so that an appropriate program will evolve. Each
farm and crop has unique characteristics which need to be
catered for in developing a program and responding to events
as the season progresses.
In addition to these
questions are those related to cost and practicality and the
degree of difficulty controlling key pests with chemical
means alone.
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The main components and
tools of a biological control focused IPM
program:
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Natural Enemies
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Parasitoids
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locally occurring and
commercially mass produced
see: www.goodbugs.org.au
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Predators
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Pathogens - locally occurring
and commercial products
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Products
include:
Bacillus
thuringinesis or B.t. products, e.g. Dipel, Novosol, Biobit, Xentari.
Nuclearpolyhedrosis
Virus (NPV) e.g.
Gemstar®, Vivus®.
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Insecticides
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Selective
insecticides
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e.g. Avatar®/Steward®, Prodigee®, Success®, Mimic®, Insegar®, Neem products etc.
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Oil and soap
sprays
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e.g. D-C-Tron®,
Natrasoap®
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Strategically applied,
occasional use of "harmful" insecticides
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For a damaging infestation
of a pest with limited spray options
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Other tools
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Pheromone mating
disruption methods
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e.g. for codling moth,
oriental fruit moth, lightbrown apple moth.e.g. Isomate®
products.
See: www.biocontrol.com.au
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Baiting and
Trapping
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e.g. yeast baits for Qld
fruit fly
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Benefits
of utilising biological control agents
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Numerous benefits arise
from utilising natural enemies. Some are obvious while
others are more hidden and difficult to quantify:
- BCA's assist in control
of some important pests which have developed high levels
of tolerance to chemical products - e.g. twospotted
mites, Heliothis, cabbage moth.
- In combination with
soft options, BCA's help to prolong the useful life of
the remaining effective chemicals - less pests are
subjected to the chemical and pests that escape the
chemical have a good chance of being eaten by a BCA.
- Some BCA's are mass produced which can enable significant reductions in chemical use. These reductions also enable the movement of local beneficials into the crop. Some of these can be very significant in there own right.
- Natural enemies can
enable control of pests in crops sensitive to
chemicals.
- Reduce problems with
withholding and re-entry periods.
- Minimise chemical
residues in the end product and the environment
generally.
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Some
difficulties with Biological Control
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Some difficulties are
usually encountered in the move to an IPM system. Practices
and routines need to be modified and new information
absorbed by the practitioners. The following are some areas
that are likely to be important:
- Regular monitoring is
necessary to identify pest outbreaks and their location
within a crop. It may take time to develop suitable
procedures and routines.
- "Soft" controls for
some pests are available but not others. If unavailable,
spot spraying with broad spectrum products may be more
appropriate than widespread spraying.
- Some damage from pests
may need to be tolerated. Some pests may be required to
support a useful population of the natural enemy.
- Good timing is
necessary when introducing natural enemies - not too
early, not too late. For example: You may need to target
moth flights, or detect early signs of a pest etc.
- Need to get natural
enemies established quickly. If introducing mass reared
BCA's, introduce appropriate numbers to facilitate quick
establishment.
- Deciding when to or not
to spray can be an issue. If soft options are available
for the pest in question this is not such an issue.
- Providing a suitable
environment. Very hot dry conditions are not conducive to
some BCA's. Adjustments may need to made to favour BCA's,
e.g. shade, windbreaks, overhead watering.
- Having an expectation
that one cannot spray at all is incorrect and may result
in failure of the IPM system. BCA's usually recover from
occasional sprays of moderately toxic products and can
remain at useful levels.
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Methods
of Introducing Bio Control Agents
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BCA's can be used in
various ways. These methods are usually divided up into the
follow categories:
- Inoculative
release: One or two releases early in pest
infestation to control pest gradually. e.g. predatory
mites in strawberries, Trichogramma in field crops,
lacewing in field and greenhouse crops.
- Regular or dribble
release method: Regular small release during likely
problem periods, used like preventative fungicides. e.g.
P. persimilis is nursery crops, Encarsia in
green house crops.
- Inundative
releases: Repeated high rate releases during periods
of pressure for quick knock down. e.g.
Cryptolaemus beetles, Trichogramma in green house
crops, P. persimilis for dosing hot spots of
TSM.
- Combination of above
methods: e.g. initial high release rate for quick
knock down followed by regular small releases.
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Getting
Started in Biological Control in Commercial
Crops
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- Seek specialist advice
from suppliers of BCA's.
- Monitor crops
regularly. Determine what level of pest you can
tolerate.
- Determine which mass
produced BCA's are suitable for your pests, crop and
district.
- Identify any local
BCA's that are likely to assist you.
- Determine the best
times for introducing natural enemies.
- Replace broad spectrum
sprays with biological or more selective insecticides if
available.
- Ensure chemical
residues have had time to disperse before introducing
BCA's.
- Identify other
practices which will assist establishment of BCA's. e.g.
wind breaks.
- If appropriate,
reorganise plantings and location of plantings to
facilitate use of BCA's.
- Experiment with part of
the crop or one planting.
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