PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
PLANT
DAMAGE
Few species feed
on living plants
DIRECT CHEWING DAMAGE.
Only the worker castes damage plants and plant material, and may comprise 80% to
90% of a termite colony. They eat out large galleries or runways through which the
workers forage for food and travel to and from the nest. Cellulose found in plants is the
basic food requirement of all termites. They may damage materials they cannot digest,
eg plastics, tuber, metal or mortar encountered during their search for food.
TREES Young and old trees and shrubs.
WOOD Buildings, fence posts, telegraph
poles, piers, wood chips and bark
used as landscape mulches.
STRAW
CROPS
Some species of grasses only.
Tubers, eg potatoes.
Stalks, eg sugarcane.
INDIRECT DAMAGE.
Termite tunnels in potato (cross section)
Weakening of structures (collapse of trees, timber) and infrastructure damage, eg
cables, plastic sheathing and conduits.
LIST OF SOME
SPECIES
Most pest
species are
subterranean.
Most small termite species in the
NT do little damage to native
plants, ornamentals or fruit trees
and rarely need to be controlled
(Andersen, et al. 2000)
The most
destructive
termite species
in Australia
The world’s worst
termite.
Not known in
Australia
Many other genera
and species
COMMON NAME SCIENTIFIC NAME HOST RANGE
(not exhaustive)
SUBTERRANEAN TERMITES .
Require a constant source of moisture. They obtain their moisture from the soil
and are generally ground-dwelling.
Tunnels are underground, usually in the top 20 cm of the soil, originating from the
nest, to reach a source of food, which may be up to 50 meter from a central colony; or
as shelter tubes up vertical objects.
They build their nests in soil, in trees and other sheltered situations. Nests are
mostly around ground level. Many nests are started in or near dead tree stumps.
OBLIGATE MOUND COLONIES
Central colony is always a raised mound. Subterranean tunnels radiate from the
central colony to food sources.
Subterranean termite Coptotermes lacteus
Qld, NSW, Vic
C. brunneus WA
Dead wood in ground (poles, fallen
trees), not a pest of buildings or
living trees. Fruit trees. Nest up to
2 m high
Spinifex termite Nasutitermes triodiae Grass, not timber in service, nest
Magnetic termite,
compass termite
Amitermes meridionalis
up to 7 m high
Grass, mound is up to 4 m high,
Orientated N-S so the E and W sides
face the morning and afternoon sun
respectively. The thin wedge faces
N at midday thus striving to keep
the nest at the preferred 30 o C. As
the morning or afternoon sun heats
up a side of the mound the termites
move to the other cooler side
NON-MOUND COLONIES
Nests underground inside living or dead trees, stumps, poles, wood in the ground.
Some species build mounds in some areas. Subterranean tunnels radiate from the
nest to food sources.
Subterranean termite
Formosan
subterranean termite
Giant northerntermite
Workers > 12 mm
Coptotermes acinaciformis
Occurs throughout Australia, this
species builds nests in mounds in the
northern (Qld) & SW areas of its
range.
All timber structures, forest, fruit
and ornamental trees. Eats out a
central pipe within trees especially
eucalypts. Packed with ‘mudguts’
or claylike faecal material. Adjacent
trees become infested via galleries
C. formosanus A destructive species damaging
houses, buildings, live trees, crops
Mastotermes darwiniensis
Most damaging species in the NT
Houses, posts, young trees, sugarcane,
etc. Threat to tree planting,
may ringbark trees. Largest soldiers
in Australia. Very destructive
where it occurs
ARBOREAL COLONIES .
Nests in trees at various heights or on top of posts. Ground contact is necessary and
galleries run down inside and outside the stem. Underground tunnels radiate from the
base of the tree or post to food sources.
Niggerhead termites Nasutitermes walkeri Decayed timber in fences in contact
with soil. Rarely attacks timber on
or in houses
Insects and allied pests - Isoptera (termites, ‘white ants’) 175