western-queensland-gardening-guide.pdf - South West NRM

Cihaas and sther fruits
Queensland fruitfly
The Queensland fruit fly (Batrocera tryoni) is a major pest in citrus, stonefruit and home
gardens. It also attacks the fruits of many native trees and shrubs.
The adult fruit fly has a wasp-like appearance, the body being reddish-brown with
lemon-yellow patches on the middle portion of the body. It is somewhat longer than a
house fly. The insects may be easily seen in trees on sunny days when conditions are
suitable for egg laying. The elongated oval eggs are laid in batches of six or seven,
under the skin of the fruit, usually shortly before ripening occurs. The larvae which
emerge from the eggs feed on the flesh of the fruit and rots develop. The fruit quickly
becomes unfit for consumption.
Control
Spray when flies are observed, with dimethoate, (e.g. Xogor) or with fenthion, (Lebaycid
or Baytex). Dimethoate should not be used on Meyer lemons, Seville oranges or
cumquats because it causes the tree to shed flowers, fruit and leaves. Both chemicals
are toxic to bees, so avoid spraying when bees are active.
An alternative and much less disruptive spray is a bait of yeast autolysate and
maldison or chlorpyrifos applied at 50 mL per tree to a one square metre patch low
down on the tree at weekly intervals. Also apply to nearby shrubs throughout the
garden to increase the area treated.
To make the spray add 20 mL of yeast and 5 mL or maldison or 2 mL of chlorpyrifos
ingredients to one litre of water.
The use of a trap such as Dakpot containing maldison to indicate the presence of flies is
recommended but it should be realised that this traps only the male fruit flies.
Sca les
Redscale
The main scale pest of citrus trees in Western Queensland is red scale (Aonidiella
aurantii). This scale is flattish, reddish and circular with a diameter of about 2 mm.
The female is wingless but the male is winged. Living young (crawlers) are produced
by the female and these select their own feeding site and secrete the scale cover.
Leaves, fruit, twigs, limbs and main branches may be attacked. Only the limbs and
main branches of open, poorly foliaged trees are infested, as the scale shows a distinct
preference for exposed, sunny sites. It is not usually found in appreciable nuinbers on
limbs and main branches, if the tree is carrying a reasonably good amount of foliage.
Affected trees lack vigour, twigs die back and the fruit must be cleaned before use.