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.Prepare a plan that fits your situation.
2.Crop, region. Know the variations, eg not in
Tasmania.
3.Identification if necessary consult a diagnostic
service (page xiv) but the adult is distinctive.
4.Monitor the pest and/or damage visually during
spring and summer. Remember you need to know
when, where, what and how to monitor
(page 39).
Citrus trees are usually monitored once or twice
from October to April, depending on development
of infestations. Check 5 randomly selected young
shoots on each tree (Smith et al 1997).
5.Threshold. How much damage can you accept? On
many plants the damage may not be significant.
On citrus if 25% or more shoots are infested on
young trees then action is needed.
6.Action. Action is rarely required on older trees. If
required, bugs on young trees may be collected and
destroyed or in severe infestations spot sprayed with a
selective insecticide.
7.Evaluation. Review your program and
recommend improvements where needed. It may be
necessary to continue monitoring trees after treatment.
Keep records so you can compare each year’s results.
Control methods
Often damage is of no economic importance and so
no control measures are required. A few bugs on a
large shrub can be ignored.
Sanitation. If only a few small shrubs, plants or
nursery stock are affected bugs can be collected by
hand. Wear gloves to avoid getting their offensive
fluid on hands. Alternatively, bugs may be shaken
into a wide mouthed container or onto a sheet.
Destroy bugs by stamping on or by some other
means. Damaged shoots may be pruned off.
Biological control. Many predators feed on
crusader bugs including other insects, eg assassin
bug (Pristhesancus plagipennis), praying mantises,
and birds. Wasps that parasitize eggs are the main
natural enemies of crusader bug.
Resistant varieties. Some varieties of host
plants are all susceptible, eg all citrus varieties are
susceptible.
Insecticides. Spot spray nymphal stages on
plants if infestation is severe. Do not spray trees
greater than 3 meters high (Table 25 below).
Passionvine bug (Fabrictilis gonagra)
is about 18 mm long, black with a red
band behind its head and red spots on the
underside of its body.
Fruitspotting bugs (Amblypelta spp.) are
difficult to see. Left: Yellow-green adult bug
about 15 mm long. Right: Nymphs.
Fig. 103. Other squash bugs (Coreidae).
Table 25. Crusader bug – Some insecticides.
What to use?
FOLIAGE SPRAYS
No products are registered specifically for crusader
bugs. Some sprays are registered for ‘bugs’ generally, eg
Group 1B, eg Rogor (dimethoate)
Various home garden sprays, eg Bug Gun (permethrin)
When & how to apply?
Application of insecticides is not usually necessary in a
home garden situation. Non-chemical measures should be
sufficient.
Follow resistance management strategies on labels.
Spot spray nymphs when first noticed.
On citrus, the addition of a wetting agent such as white oil
to the spray will make it more effective.
Insects and allied pests - Hemiptera (bugs, aphids, etc) 149