PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
Pest cycle
There is a gradual metamorphosis (egg, nymphs,
workers, soldiers, kings and queens). Once a year (or
more often, during warm humid weather) winged males
and females leave the nest in thousands. After a short,
fluttering flight they alight on the ground, cast off their
wings, pair and start to form new nests in a gallery or
chamber in the ground adjacent to timber or an old
stump. A few survive to found new colonies of which
they become ‘king’ and ‘queen’. Eggs are laid and new
generations of worker and soldier termites are
produced. The queen may live and continue to lay eggs
for many years. The destructive potential of the colony
is not fully developed for many years; a colony from a
single pair reaches about 100 strong in 3-5 years.
‘Overwintering’
As all stages in colonies. Reproductives in termite
colonies can survive for many years. Soldiers and
workers for only short periods of time.
Spread
Workers of some types may travel up to 50 meters
through galleries searching for food but cannot
establish new colonies.
By winged adult males and females flying. In
summer during hot humid weather flights may
occur inside buildings late in the day or to lighted
windows at night.
Movement of timber or wood carrying eggs, a
queen or nymphs.
Conditions favoring
The main pest species are subterranean termites
which must have contact with the ground or access
to a continual source of moisture.
Warm soil with an abundant supply of food in the
form of wood or other cellulose material.
Trees with fire scars.
Termites are generally more abundant in the
tropical and semi-tropical regions of Australia.
Old living trees often with fungal decay appear to
be most susceptible to termite damage (except a
Coptotermes sp. that is only found in the tropics).
Potatoes or fruit trees planted in freshly or
incompletely cleared land or adjacent to
bushland may be attacked. Infestations start from a
dead tree stump or log in the potato field, orchard
or on adjoining land. Outside rows are more likely
to be attacked than inner rows.
The adoption of zero till and stubble retention
practices has resulted in the re-appearance of
subterranean termites in some cropping lands.
Wooden stakes of susceptible timbers or sapwoods
used for supporting plants can attract termites.
Mulches of chips of wood, bark and nut shells are
also attractive.
Management (IPM
1. Obtain/plan. In most situations termite control
should be carried out by licensed pest control
operator.
2. Crop, region. Pest species vary according to region.
Obtain leaflets on local species. It may be necessary to
treat areas before planting fruit or other trees.
3. Identification. Consult an arborist, licensed pest
controller or a diagnostic service (page xiv).
4. Monitor pest and/or damage and record results as
recommended by a trained pest control specialist.
– Regular inspections by trained personnel of
trees, fences, where termites have been a problem.
– Early warning systems. Bait stations (usually
containing an attractive wood) are placed in areas
where termites may be foraging. The termites
aggregate at the station and continue to feed. Use
mountain ash (E. regnans) as bait for termites less
resin in it. Some termite monitoring and baiting
systems are designed to be spread throughout the
colony by the worker termites.
– Monitor mulch by vigorously raking it back and
forth at least twice a year, especially during sultry
summer months when queens are likely to be
starting new colonies.
5. Threshold is usually a nil tolerance if it is a species
that devastates trees, plantations, buildings. How
much damage can you accept?
6. Action. Professionals will undertake any treatments
required and may recommend treatments that you can
carry out, eg removal of unwanted timber, etc.
7. Evaluation of the program may require an annual
inspection by trained personnel. Keep records of
treatments, inspections and results. Put improvements
in place if necessary.
Table 35. Comparison of termite, borer and wood rot damage.
Tree
trunk
External
damage
Internal
damage
TERMITE DAMAGE BORER DAMAGE WOOD ROT
Flight cuts, through
which winged
termites leave
parent colony.
Often no obvious
damage, timber
hollowed out from
within.
In some cases
distinctive gallery
running on trunk
or structure.
Photo NSW Dept of
Industry and Investment
Fluted areas, termite damage, it is
easy to distinguish from borer damage,
and wood rot (fungal decay).
‘Mud guts’.
If active, termites seen.
Timber hollow and light in density.
Flight holes of
various sizes
depending on
species of borer.
Fine timber dust.
Shape, size of holes
and host indicate
which borers
See also page 111.
Individual tunnels may be oval or round,
may or may not be filled with frass.
Galleries below bark.
Presence of either sluggish larvae or in
some cases, adults below bark.
If decay is advanced,
fruiting bodies of
various colours, eg
red pink, white or
brown and of various
shapes and sizes,
may have developed
See also page 361.
Heartwood stained with coloured or white
threads, may be soft, lighter in density.
When dried out wood is friable, very light in
weight with no structural strength.
No hollow fluted areas (termites) or holes
(borers).
Photo NSW Dept of Industry
and Investment (E.H.Zeck).
178 Insects and allied pests - Isoptera (termites, ‘white ants’)