Transcript Citrus pests - northernarborists

Pests of Orchards
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California red scale
Grape vine moth
Citrus leaf miner
White louse scale
Queensland fruit fly
Phylloxera
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Anthracnose
Lemon scab
Melanose
Spined citrus bug
Other problems
deficiencies
California red scale
• Order- Hemiptera ( hard)
• Appearance – The adult female cover circular, conical
orange/red. The winged adult male cover is oval &
grey. Crawlers & adults inject a toxic poison in saliva
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California red scale
California red scale crawlers
Adult male California red scale.
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California red scale
Damage- All of the above
ground may be
infested= Fruit blemishing, leaf yellowing,
fall, twig & branch die back
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California red scale
Plants affected-
Citrus,Acacias,Willows, Olives. Most
widespread pest of citrus in NSW.
Conditions-
Prefers dry inland or
coastal, dust covering plants
Very troublesome
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pest
California scale Control
• Biological-Red & blue ladybird beetle larvae ( Chilocorus
spp). The adult beetle lays her eggs under scale cover=
larvae feed
• Aphytis melinus wasp lays her eggs under the scale cover
of a second instar unmated female scale= hatched larvae
feed, adult wasp also feed
• Cultural- Keep trees healthy, do not over fertilise / overwater,
• Control ants. They severely disrupt red scale parasites while
tending red scale
• Avoid excessive dust build up on leaves and fruit, (eg from
manure mulches, kaolin clays)
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Californian scale - Control
Cultural - Fine, talc-sized particles of ash from bush fires can
also disrupt biological control. Washing trees to remove dust or
ash particles can help solve this problem.
Heavy fogs, drizzle, or rain can also help by either removing
dust and ash particles or causing them to adhere to the leaf
surface.
Chemical-
White/pest oil ( not on blossom)
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Citrus leaf miner
• Order- Lepidoptera
• Appearance –usually observed when leaves are
damaged by larvae tunnels and pupal stage
• Damage-The larvae tunnel down new shoots
near tips or junctions = wilting , distortion and
obvious tunnelling
• Plants affected Citrus
• Common on coast and has a major impact
inland on citrus orchard industry
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Citrus leaf miner - Damage
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Citrus leaf miner
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Life cycle
• Damage occurs in later summer and autumn
• Larvae tunnel in surface layer of new leaves
• Pupal chamber is formed at the end of the
larval stage where the larva wraps itself in a
silk casing at the edge of the leaf.
• Adult lays eggs along leaf margin 0.3 mm in
size
• 14 – 17 days complete lifecycle
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Control
• Winter fertilising to promote new growth in
spring
• Prune off affected leaves and destroy
• Natural predators can control from 20 –
90% of all infestations
• White oil is the only recommended
chemical control for home nurseries
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White Louse Scale
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White Louse Scale
• Generally found on trunk and lower branches first
• Spread to upper twigs and leaves
• Generally plant has branch die back and poor
vigour
• Control is white oil treatment
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Queensland fruit fly
• Order• Appearance
• Damage
• Plants affected
• CONTROL
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Lemon scab
FUNGUS
Appearance/ Damage-Irregular
scabby areas on fruit, sometimes
leaves & twigs . Wart-like
outgrowths sometimes scabbed.
Severe shedding of young fruit,
external quality affected
Plants affected-Citrus ( mainly
lemons & mandarins)
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 Spread- Rain, wind
 Control- Occurs during damp weather & only on
immature fruit, coastal areas. When symptoms seen
it is too late to save infected fruit. Need for
preventative spraying before next crop.
 Chemical- Apply Bordeaux (+ white oil) in spring ant
half petal fall and again in late Jan/early Feb at
blossoming of second crop
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Melanose
• FUNGUS
• Appearance/ Damage-Small
Reddish to dark brown spots
on leaves & fruit. Streaky if
spores are washed by rain,
skin of fruit may become
cracked and have a ‘mudcake’ appearance
• Young leaves & fruit are
susceptible & usually occurs
on older trees in wet warm
conditions
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Melanose
• Mudcake or
sandpaper symptoms
of melanose on
grapefruit.
Tearstaining caused by
melanose spores washed
down the fruit by dew or
rain.
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Melanose
Plants affected-Citrus-Washington
navels,Emperor
mandarins & lemons
Spread- Water – dripping & splashing
Control- remove & destroy infected parts,Copper oxychloride
+ white oil at petal fall
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Bronze Orange Bug
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Piercing and sucking mouthparts
True bug
Gregarious
Damage the tips of new growth and cause leaf
distorton
• Toxic urine from adults and older nymphs
(eyes and hands, sensitive skin)
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BoB Control
• Hand removal shaking and spray with high
pressure water
• Chemical use only white oil
• White oil affects most predators as well
• Affect new growth so prune damaged growth.
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Spined Citrus bug
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Summer fruit drop
• Citrus normally shed large numbers of
fruitlets shortly after blossoming in the
spring and at early fruit set (pea size).
• when warmer weather places stress on
the tree.
• related to lack of water at, or soon after,
fruit set.
• Root diseases and lack of nitrogen or
trace elements may also be responsible.
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Rind splitting
• Rind splitting of fruit, particularly in navels,
also occurs before or near maturity as a
result of climatic factors, specifically a drop
in average temperatures and an increase in
relative humidity at a time when the rate of
fruit growth is decreasing.
• There is no control for the disorder.
Preharvest drop
• Preharvest drop in the autumn before fruit is
fully mature is a common problem with navels
and grapefruit. Some of this drop is natural,
but in coastal areas fruit stung by Queensland
fruit fly during the late autumn colour-change
period is also very prone to drop. Some
mandarin and lemon varieties will also shed
fruit when damaged by the spined citrus bug.
Brown spot infection in mandarins will result
in fruit drop.
Alternate cropping (biennial bearing)
• Alternate cropping (biennial bearing) is a
common problem with many citrus varieties,
such as Valencia orange, Wheeny grapefruit,
and mandarins.
• Pruning or thinning of the heavy crop and
early harvesting will assist in reducing the
problem.
Second crop fruit
• Sometimes orange trees will produce
blossoms in the autumn after a stress period,
and set a second crop. This fruit is often of
poor quality (thick skins and low juice content)
and is susceptible to fruit fly attack. With
lemon trees, however, these intermediate
crops are desirable
Grape vine moth
Order- Lepidoptera
Appearance
– Adult- black moth
with yellow markings & tuffs of orange
hair at the tip of the abdomen. Larva
– blend of green, yellow, black with
red markings at sides and a red band
over body at hind end. Scattered
white hairs over body.
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Grape vine moth
• Damage- Larvae skeletonise
leaves, defoliate to main
stems
• Plants affected- Grapes,
Fuchsias, Parthenocissus
• Prefers lush growth
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Grapevine moth control
Oechalia schellenbergii.
• Biological- Dipel, birds,
wasps
• predatory shield bug
Oechalia schellenbergii.
• Natural predators are usually
effective
• Physical- hand pick off from
leaf dersides
• Chemical-Only spray in
severe infestation
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Grapevine moth control
Larva being eaten by
mating shieldbug
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Phylloxera
• Order- Hemiptera
• Appearance –This aphid can live
below or above ground & when
swelling or galls are cut open
aphids =green - yellow
• Damage- Roots- have fleshy yellow
galls on the fine roots ( may be
curved in a S shape).Leaves have
fleshy yellowish irregular
swellings. Infected plants are weak
& do not produce good crops
• Plants affected- stressed grape
vines (which are less able to repel
their attack), in heavy soils &
humid environments and warm
temperatures.
• AN EXTREMELY SERIOUS PEST OF
GRAPEVINES
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Phylloxera
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Phylloxera -Damage
•Root-feeding stages are the most damaging, causing a loss in plant vigour,
wilting and leaf yellowing. Vines may eventually die within 3-10 years.
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galls and inside the leaf galls.
Phylloxera -Damage
Galls on infected leaves
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Phylloxera -Damage
• The effect of phylloxera
aphids feeding on the roots
is to cause the vines to get
progressively weaker, and
they produce fewer leaves
and grapes.
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Phylloxera control
• There is no chemical control & no economic
means of removing it from the soil once it is
established
• Cultural- QUARANTINE regulations, grow on
resistant root stocks
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Anthracnose
• VARIOUS FUNGUS
• Appearance/ DamageSmall to large, dark
circular spots or sunken
lesions with raised rim on
leaves, stems & fruit
• Can occur at any stage of
growth, twig die back,
corky spots on fruit, fruit
drop & rot
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Anthracnose
Anthracnose leaf spot on watermelon
leaf
•Stem and pods have black fruiting
bodies, “acervuli,” with black hairs,
“setae.
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Anthracnose
• characterised by discrete
lesions that are usually
found along leaf veins. In
severe cases these lesions
may run together and kill
the entire leaf. Young
leaves may become
distorted as healthy tissue
continues to grow around
dead areas.
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Anthracnose
Colletotrichum acutatum
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Anthracnose
• Sunken lesions,
slightly paler than the
healthy tissue, are
symptoms of tomato
anthracnose.
Black fruiting bodies
are visible on this
close-up of the lesion.
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Anthracnose
• Tomatoes develop sunken
spots on ripe fruits, the
central parts of which turn
dark.
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Anthracnose
Plants affected- Citrus, grapes, stonefruit, avocadoes etc
Spread- Water, wind, animals, tools, infected plants
Control- remove & destroy infected parts, crop rotation,
disease free seed, improve drainage, air circulation,
watering
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Peach leaf curl
Control- remove & destroy
infected
parts,Copper oxychloride before bud swell or
late Winter
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