PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
Summary - Some exceptions (contd)
LERPS
MEALYBUGS
SCALES
WHITEFLIES
SOME DISTINCTIVE FEATURES
1.Adults are similar in appearance to
aphids with wings, usually free living
and can jump (hence the nick name
of jumping plant lice).
2.Wings held roof-like over body.
3.Vary in size, up to 10 mm.
4.Nymphs of some species shelter
beneath a lerp covering which is
easily removed.
1. Oval to elongated body up to
20 mm long.
2. Soft-bodied and quite mobile (move
very slowly).
3. Frill of white filaments around
margin of body.
4. Secrete a white waxy meal.
5. Closely related to scale insects.
1.Female wingless and stationary and
degenerate, male is winged.
2.Female is larger than the male.
3.Female is protected by secretions:
4.Armoured scales:
Usually very small, may look like
dust
Soft flattened body under a
separate hard scaly covering.
Little if any honeydew
5.Soft scales:
Larger than armoured scales.
Soft body with, initially no
covering. However, the upper
surface of adults is usually tough or
protected with a waxy or mealy
secretion.
Produce honeydew in varying
amounts which attracts ants and on
which sooty mould grows.
1.Adult male and female insects
winged.
2.Up to 3 mm wingspan.
3.Body and wings covered with white
powdery material.
4.Two pairs wings of almost equal size,
held flat over body.
5.Nymphs oval and flattened, not
mobile. Parasitized nymphs turn
black.
PLANT DAMAGE
DIRECT SUCKING DAMAGE.
LEAVES Dead areas, eg many species
which attack eucalypts
Defoliation, eg as above
Mottling, eg as above
INDIRECT DAMAGE.
Secrete honeydew.
Lerp coverings
DIRECT SUCKING DAMAGE.
LEAVES Wilting and death eg longtailed
mealybug especially on
greenhouse and indoor
plants
ROOTS Death, eg root mealybugs
GENERAL Death of plant, eg many
species of mealybug
INDIRECT DAMAGE.
Disfigurement from presence and
honeydew and waxy deposits
DIRECT SUCKING DAMAGE.
LEAVES Yellowing, eg black scale
Leaf fall, eg red scale (citrus)
FRUIT Disfigurement, eg red scale
STEMS Dieback, eg San Jose scale,
TRUNK gumtree scale
GENERAL Stunting, eg white louse scale
Dieback, especially armoured
scales
INDIRECT DAMAGE.
Soft scales produce honeydew, eg soft
brown scale.
Unsightly, eg white wax scale.
Loss of overseas markets, eg San Jose
scale. Citrus fruit with scale on local
markets reduces value
DIRECT SUCKING DAMAGE.
LEAVES Mottling, eg greenhouse
whitefly (GHWF)
GENERAL Death of seedlings, eg GHWF
Reduced vigour, eg silverleaf
whitefly (SLWF)
INDIRECT DAMAGE.
Honeydew and associated sooty mould
Overseas they are known to transmit
some virus and virus-like diseases.
146 Insects and allied pests - Hemiptera (bugs, aphids, etc)