PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
‘Overwintering’
Millipedes ‘overwinter’ as adults outdoors in soil,
under logs and under leaf litter in sheltered places.
Spread
By crawling, adult millipedes can probably walk
a maximum of several hundred meters each year.
Transportation of soil, pots or container plants
from infested areas.
Transportation of wood chips and compost from
infested areas.
On/in tyre treads of vehicles.
Conditions favoring
Damp undisturbed organic mulch, leaf litter.
Areas where winter weeds such as soursob form
a more or less continuous ground cover.
Millipedes are generally not numerous in lawns,
cultivated areas or bare ground.
Management (IPM)
Are you a commercial grower or home gardener?
1.Plan. If millipedes are an ongoing problem, then
prepare a management plan.
2.Crop, region. Recognize variations. Locate plants
or main breeding areas where control is required.
3.Confirm identification and be familiar with
their life cycle, conditions which favour their
development and where they ‘overwinter’ when they
are not a problem, etc. Consult a diagnostic service if
necessary (page xiv).
4.Monitoring millipede numbers and damage will
indicate when peak populations are likely to occur
(page 39). Millipedes are observed at night. Record
results.
5.Thresholds should be determined for crops at risk.
How much damage can you accept, eg economic,
aesthetic, environmental?
6.Action. Take appropriate action when any threshold
is reached. Remember, only if seeds or seedlings are
being injured should treatment be considered.
7.Evaluation. Review IPM program to see how well
it worked. Recommend improvements if required.
Control methods
Sanitation.
These pests are best controlled by cleaning up
the areas where they breed, so that the supply of
food and shelter is reduced as much as possible.
This is the best way of controlling them in a
home garden situation.
Biological control. Several biological
control agents are being research including:
A parasitic fly which is a natural enemy of the
black Portuguese millipede overseas, is being
researched and quarantined in Australia prior to
its possible release. It is important to be sure that
the parasitic fly does not attack native
millipedes.
A nematode (Rhabditis necromena) has been
released in SA to control the Portuguese
millipede. It attacks only millipedes and not
other animals or plants. The millipedes ingest
numerous nematodes which then perforate the
gut of the millipede. The nematodes are active
during late autumn and winter After introduction,
they take several years to reduce millipede
numbers. Householders living next door to areas
of bushland report that nematodes do not reduce
the numbers of millipedes invading houses
probably because of the many millipedes living
in the bushland nearby.
Physical and mechanical methods.
These are mainly used to control the black
Portuguese millipede which invades houses and
include barriers of various types and light traps.
Insecticides.
See Table 46 below.
Remember that although millipedes
(and earwigs) invade houses, they do
not breed inside the house. They can
be swept up and disposed.
Table 46. Millipedes – Some insecticides.
What to use?
HORTICULTURE SITUATIONS
Baits, eg
Group 1A, eg Baysol Snail & Slug Bait (methiocarb)
Sprays, eg
Group 1A, eg various
Group 1B, eg various
Group 3A, eg various
Garden surface sprays, eg various
When and how to apply?
Insecticides should only be applied after plant
damage had been confirmed.
Insects and allied pests - Millipedes (Diplopoda) 215