PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
Resistant varieties.
Plant WFT-tolerant cultivars if practical. This does
not necessarily reduce spread of TSWV (page 286).
Plant quarantine.
AQIS. Consignments to some countries are
fumigated and/or destroyed if thrips are found.
All plants and cuttings imported into Australia
are subject to mandatory treatments to kill thrips
and other insects. Flowers, vegetables and fruit
are subject to inspections and if infested,
are treated. Some products may be destroyed.
State/Regional quarantine. Status of WFT
within Australia is under constant review.
– Protocols for entry to various states may involve
inspection, treatment, or sourced from a property
free of this pest (area freedom).
– Check with transporters to ensure plants do not
become contaminated after they leave the property.
– Non-hosts are plants not known to be hosts of WFT
and include banana leaf, bulbs without leaves,
conifers, ferns, roses (dormant and without leaf),
trees (deciduous and without leaf). Non-hosts pose a
very low risk of transporting WFT so that
certification of WFT-free plants may not be needed.
A declaration must accompany plants indicating that
‘only non-hosts’ plants are being transported.
Local quarantine. Do not bring plants onto your
property or return them from market unnecessarily.
– Quarantine new plants and check for thrips, if
present treat before placing with rest of stock.
– Separate growing and retail areas.
Pest-tested planting material.
Only buy certified WFT and TSWV-free seedlings
and cuttings from reliable or accredited
suppliers. Greatest risk is from cuttings.
Ensure stock plants for cuttings are thrips-free.
Physical & mechanical methods.
Insect microscreens (100-200 mesh) over
greenhouse vents and doors prevent thrips
invasions from outside (anti-thrips net).
Greenhouse plastics. WFT prefer to enter
tunnels that transmit higher levels of UV light.
So UV-absorbing greenhouses plastic films could
be used to influence flight behaviour.
Insecticides.
Except for WFT, thrips are easily controlled with
current insecticides. Most states have a Western
flower thrips (WFT) Insecticide Resistance
Management Plan. Access a copy.
Permits may be required.
Intervals between sprays. Insecticides kill
nymphs and adults, not eggs (which are inside
the leaf) and pupae (which are mostly in the
soil). Several sprays may be prescribed to cover
the time taken for eggs to hatch into larvae and
for pupae to develop into adults.
Resistance management
– WFT is notorious for its resistance to insecticides.
– Only a few insecticides give any practical control of
WFT which quickly becomes resistant to
organophosphates, carbamate and synthetic
pyrethroid insecticides.
– Follow Croplife Australia Resistance
Management Strategies for WFT on labels.
Rotate insecticides as recommended to delay
development of resistance.
– Use application techniques, eg sprayer, aerosol,
fogger, that give a good spray coverage of tiny
droplets to contact thrips hiding in buds, etc.
– Hydroponic growers incorporate insecticide into
fertigation water. Weed removal is still essential
otherwise WFT may again become a problem.
– Consult various references (Stephens 2000).
Once harvesting has commenced it is not
possible to follow insecticide usage plans.
Insecticides may be toxic to bees (page 114).
Pest stimulation (increased egg laying) after
exposure to residues of Mavrik (tau-fluvalinate),
Kelthane (dicofol) and malathion occurs with
citrus thrips. Whether this occurs with WFT is
unknown, do not apply pesticides preventatively.
Herbicides. Identify and eradicate non-crop
hosts of WFT, including weeds.
Effectiveness of insecticides may be improved
by increasing greenhouse temperatures from
21-23 o C to 26-28 o C. Once in the air thrips have a
greater chance of being exposed to insecticide
and mortality rates increase by about 25%.
Table 24. Some insecticides for Western Flower Thrips and other thrips spp.
What to use?
FOLIAGE
Group 5, eg Entrust Naturalyte, Success Naturalyte
(spinosad)
Each state has management strategies for WFT,
check current recommendations in your state for
your crop, eg
WFT Insecticide Resistance Management Plans
PERMITS MAY BE REQUIRED
SEED TREATMENTS
Group 4A, eg Picus Seed Treatment (imadicloprid) protects
cotton seedlings from injury due to onion thrips
(Thrips tabaci) and other thrips
FERTIGATION, FUMIGATION
TREATMENTS UNDER INVESTIGATION
Group UN, eg soil drenches of Azamax (azadirachtin) and a
foliar spray program of Neem (azadirachtin)
Spray oils
When and how to apply?
Remember WFT can be difficult to target with
insecticides as they lurk in inaccessible places.
For effective control it is necessary for the
insecticide to have a residual activity of 2-4 weeks.
Only larval and adult stages susceptible to insecticides.
Follow Croplife Australia Resistance Management
Strategies
Seed treatments protect certain crops from injury from
thrips and certain other sucking insects and subsequent
spread of virus diseases.
Insecticide in fertigation water, eg hydroponic lettuce.
Some growers fumigate soil and greenhouse between
crops (page 61, Table 6.)
140 Insects and allied pests - Thysanoptera (Thrips)