PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
2
INTEGRATED DISEASE MANAGEMENT (IDM)
MAIN STEPS
PLAN
PLAN
PLAN
Emphasis today is
on diagnostics,
especially of
soil diseases
An exotic nematode
may be in Australia for
years before being
detected and identified
In turf, thresholds
depend on grass spp.,
mowing height,
soil compaction,
soil type, and
presence of other
root pathogens
?
CONTROL METHODS
Legislation
Cultural methods
Sanitation
Biological
Resistant varieties
Plant quarantine
Disease-tested material
Physical/mechanical
Pesticides
Organic, BMP, etc
X
IDM avoids broad spectrum chemicals. Use control measures strategically and early be
it chemical or biological or both and potential major pest problems may be avoided.
Use control methods which maintain pest populations at acceptable levels
1. Plan well in advance of planting the crop. Keep records, eg variety planted, source
of planting material, planting/sowing dates, temperature, irrigation, fertilizers and
pesticides. Training courses are available for consultants and pest managers which
include how to sample, monitor, interpret results and apply IDM.
2. Crop, region List nematode and other plant problems your crop is susceptible to in
your region. The IDM program will depend on the crop, region. Management
programs for nematodes are available for turfgrass, vegetables, etc.
3. Identification Confirm identity of the nematode alleged to be causing damage,
it will probably be necessary to consult a diagnostic service to identify the genus
and species (page xiv). Obtain a Fact Sheet on the nematode problem so you
understand the life cycle, how to prepare soil and plant samples for extraction, etc.
Biological Crop Protection www.biolcrop.com.au/
NemaSYS (CBIT, Uni of Queensland) is a multimedia package containing
information on nematodes commonly found in crops and pastures around
Australia. It provides a greater understanding of the biology of nematodes, and
a sound background for monitoring and control.
What can specialist nematode advisory services do?
– Provide information on sampling.
– Identify nematode species.
– Monitor pest species and natural enemies, keep records of damage thresholds.
– Interpret results of analysis, evaluate treatments.
– Provide advice on control options to maintain pest populations at acceptable
levels. Results indicate some unnecessary use of nematicides.
4. Monitoring Know when, where, what and how to monitor.
When to monitor? Pre-plant nematode soil analysis is necessary where root
knot and other nematodes have been a problem in previous seasons. Monitor
crop when growth is generally unthrifty, wash potting media from roots and
examine under a microscope for evidence of galls. Assess galling on roots in
the field at the end of season to indicate the degree of infestation for the
following crop.
Where, what and how? Seek advice before collecting soil samples, as you will
need a professional interpretation of the results.
Why monitor? Most nematicides are highly toxic and some are being phased
out. Use of most substitutes requires continuing monitoring of nematodes
and more knowledge as they are not equally effective against all nematodes and
other diseases organisms. Use should then be limited to situations where a need
for the chemical has been demonstrated and the lowest rates required for normal
plant growth and yield used, rather than applications on a routine or calendar
basis. Record and interpret results professionally. Monitoring also indicates
the effectiveness of earlier control measures.
5. Threshold.
There is usually a consistent relationship between nematode populations and
the level of crop damage observed (Stirling 1999).
Very low densities of nematodes can cause economic damage in some crops
while others can tolerate much higher nematode populations (Stirling 2000).
Establish damage thresholds for a particular species on a particular crop in a
particular region. Economic thresholds can be difficult to determine and
market values cannot always be predicted.
Thresholds vary depending on the nematode, life cycle, rate of reproduction,
survival, crop tolerance and environment. Conditions are important because
plants can tolerate more nematodes under good conditions than under stress.
A competent nematologist should examine the affected plants and/or do a soilplant
root test to determine whether threshold levels of damaging plant parasitic
nematodes are present and whether a nematicide application is advisable.
6. Action/control will depend on monitoring and thresholds and applying
preventative controls at the correct time. Reduction in use of nematicides can be
achieved by integrating chemical with non-chemical means of control, eg crop
rotations, resistant/tolerant cultivars and rootstocks, quarantine measures,
nematode-tested planting material, biocontrol and chemical control. Nematode
populations can be managed. Control methods, other than nematicides, are
becoming more important and include precision agriculture, improved nematode
identification, assessment of nematode populations, genetic engineering of crops
and host resistance. Advisory services (extension or private crop consultants)
provide effective management of nematodes.
7. Evaluation Review IDM program to see how well it worked. Recommend
improvements if required.
262 Nematode diseases