PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
Management (IPM)
Are you a commercial grower or home gardener?
1. Access/prepare a plan that fits your situation.
Various IPM programs are available, eg for citrus,
cotton, roses, strawberries and other crops.
2. Crop, region. Recognize variations.
3. Identification can be difficult, ensure damage is
not caused by other mite species or by sucking insects.
Consult a diagnostic service if required (page xiv).
4. Monitor mites, predators and damage regularly (page
39). Know when, where, what and how to monitor.
Monitor with a small hand lens or employ a monitoring
service. Inspection and trapping of 2-spotted should start
when plants/cuttings first arrive and continue until day of
plant sale (also for whitefly, aphids etc). This will alert
you to hot spots or flare-ups so that you can order
predators or handpick badly affected leaves and help
prevent other pests, diseases and nutritional issues.
Different crops require different monitoring procedures.
Access information for your crop, eg roses, citrus, cotton.
5. Thresholds have been established for some crops.
Growers may have to accept some damage,
providing it is not causing economic loss.
Citrus pest and predators. Threshold is more
than 20% fruit or leaves infested.
6. Action/Control. Take appropriate action when
any threshold is reached, eg
Do nothing, use cultural and sanitation controls or
water sprays.
Release predators. Do not spray chemicals
hazardous to predatory mites. It may be necessary
to apply a corrective selective miticide to assist
predators if monitoring shows a need.
just before mite
population increases to the stage of overcrowding
when they are likely to ‘escape’.
to control twospotted mites as
long as possible.
7. Evaluation. Review IPM program to see how
well it worked. Recommend improvements if
required. Continue monitoring after treatment and
consult previous year’s records for comparison.
Control methods
Cultural methods.
Appropriate irrigation of outdoor and indoor plants
can reduce the effects of infestation. Used in
greenhouse flower-growing sometimes.
Outdoor container plants can be moved from hot
sunny positions to cooler, more sheltered sites.
Plants such as violets in hot sites can be replanted
in cooler, shaded areas.
Sanitation.
Destroy weeds and old crop residues which harbour
mites and help to buildup mite populations.
Keep glasshouse clean. Avoid handling infested
material and brushing clothes by infested plants.
Biological control.
Natural enemies.
–Predators include tiny black mite-eating ladybird
(Stethorus spp.), native mites (Euseius victoriensis,
E. eliniae), lacewing and fly larvae, thrips
(Scolothrips sexmaculatus).
–Fungal diseases (Neozygites spp., Hirsulella
thompsonii) in coastal areas. Naturalis-O
(Beauveria bassiana) is available overseas.
move over
leaves and other plant parts and prey on eggs,
nymphs and adults of twospotted mites. Predators are
also dispersed in wind from cooling fans and on
workers’ clothing. Two insecticide-resistant
predatory mites have been released in Australia.
– to control twospotted
mite in apple orchards and rose gardens in IPM
programs.
– can be purchased from
several private companies for use in IPM programs.
Adult Persimilis eat from 5-20 prey (eggs or mites)
per day but they must have prey to feed on. IPM will
not eradicate 2-spotted but will manage them at a
level where there is no economic damage.
Persimilis move faster than 2 spotted mites, are
orange and pear shaped are easy to recognize using
a hand lend or x10 (page 203, Fig. 126).
– Suppliers provide information on when to release
predators, how to use them effectively and which
pesticides may be used. Predators are not resistant to
all pesticides. Home garden packs of predatory mites
are available. It is usually recommended that
predators be released in spring, eg early September.
Follow release instructions provided by the supplier.
Regular introductions are more effective in roses and
ornamentals in glasshouses.
List of suppliers www.goodbugs.org.au/
– Monocultures. It is easier to biologically suppress
twospotted mites where only one crop is grown, eg in
apple orchards, orchids, rose gardens and cucurbit
crops. It is more difficult to use them successfully in a
home garden situation or in glasshouses where many
different plants are grown.
– aid in the development and dispersal
of predators for control of plant pests, especially
twospotted mites. They enhance persistence of
predatory mites and improve. Banker plants in light
weight containers can be moved to increase longrange
dispersal of predators and be removed from
direct harmful pesticide or fertilizer applications.
Resistant varieties.
Where twospotted mites are a constant problem,
consider planting less susceptible species or
varieties if practical.
Umbrella and cocos palm have some resistance.
Plant quarantine.
Local quarantine. Avoid re-introducing infested
plant material to properties. Plants brought into a
nursery or onto a property should be thoroughly
inspected and treated if necessary. Avoid
introducing plants from areas where resistance to
miticides is a problem.
Pest-tested planting material.
Avoid taking cuttings from infested plants or
introducing/transporting infested plants.
Brushing. 40 strokes twice daily or shaking of
plant shoots has been shown to consistently
reduced mites (and thrips) populations on some
greenhouse plants.
High volume high pressure can
temporarily suppress populations by dislodging
mites but may damage soft foliage.
Miticides. control/suppress certain mite species.
Follow Croplife Science Resistance Strategies
and Resistance Warnings on labels.
– Twospotted mites have developed resistance to
most organophosphates and organochlorines.
– Most serious mite infestations can be traced to
continued use of one miticide, resulting in
development of a resistant population. Generally the
more often a chemical has been applied the greater
the resistance problem.
– Use insecticides
alternate groups to prolong use of and avoid
development of resistance.
– Check resistance recommendations on labels.
Application. Mites generally inhabit leaf undersurfaces
and are difficult to contact with sprays. In
orchards, high-pressure, high-volume sprays
thoroughly drench trees and leaf undersurfaces. If
dense foliage interferes with mite control, prune
trees to open up the canopy. Webbing is inclined to
repel spray droplets. Poor spray coverage and time of
year can result in poor mite control.
204 Insects and allied pests – Mites (Arachnida, Acarina)