citrus disorders - plantwise · front cover: hilda gomez, usda . citrus 3 contents sign or symptom...

1CITRUS

KNOWLEDGE FOR LIFE

CABI PEST AND DISEASE PHOTOGUIDE TO

Citrus disorders

2 CABI PEST AND DISEASE PHOTOGUIDE

Introduction

This photo booklet has been produced by Plantwise to aid Plant Doctors in diagnosing the most common pests, diseases and abiotic problems of Citrus around the world. The booklet is organized by plant part with similar looking signs and symptoms displayed together.

Observe the symptoms presented on the sample and then compare what you see with the photos in this guide. The guide is formatted on symptom and not causes (except for insects). Therefore it is possible to turn to the section which relates to the symptom you are seeing without knowing the cause. The photos are cross referenced and so photos showing the various features of a syndrome are easily identifiable. Many of these pests and diseases attack all members of the citrus family but others do not, host range is indicated alongside the name of the causal organism.

Citrus is a crop attacked by a many pests and pathogens, some of which have been transported around the world with the planting material. This guide is a global one and bear in mind that many of these pests shown are not present in many areas of the world.

The aphids and scale insects (Coccoidea) are conspicuous, and unsightly especially when accompanied by sooty moulds; but in most situations these insects are kept under control by natural predators and parasites. The defoliating caterpillars and beetles do not usually have any effect on crop yield, but they can retard young plants. Some scales, thrips and mites affect the surface of the fruits and spoil their appearance. The fruit boring flies (Tephritidae) and caterpillars (Tortricidae, etc.) can cause serious damage and the adult insects are difficult to kill.

The positive identification of a pest does not necessarily mean it has to be controlled and under the correct conditions pests will not become a nuisance as natural means will develop which will prevent their numbers becoming a problem. However consider that some of these insect pests can vector extremely damaging viruses.

Diseases do not become self-limiting in the same way as insect pests and control will often be required if weather conditions are conducive to disease spread.

Evaluation of photosheets during a course in Nicaragua (Yelitza Colmenarez, CABI)

Front cover: Hilda Gomez, USDA

3CITRUS

Contents

Sign or symptom Box

Insects 1 – 52

Leaf 53 – 72

Edible portion 73 – 99

Stem 100 – 105

Root 106 – 108

Whole Plant 109


1

Asian fruit fl y Bactrocera invadens All

• Adult is 8 mm long with a brown head • Body colour is variable, but with yellow and dark brown to black

markings on the mid section where the wings attach. The wings are clear

• The abdomen (bottom) is oval with a characteristic T-shape along the upper abdomen

Photo: Viwat Wornoayporn / IAEA

198

2

Mediterranean fruit fl y Ceratitis capitata All

• Adult is 5-6 mm long with a brown head and red and blue iridescent eyes

• The mid section (thorax) is black with white and yellow markings • The abdomen (bottom) is yellow with two grey bands • The wings are clear but with distinctive yellow and brown bands

along and a black wavy pattern at the wing base

Photo: The Agricultural Research Service, USDA, Bugwood.org

298

3

African citrus psyllid Trioza erytreae All

• Adult 4 mm long with a light-brown body. They have large wings and clearly outlined veins. They will often jump and fl y when disturbed

• Feeding results in raised, black spots (1-4 mm in diameter) on the leaf surface

• Adults typically adopts a head down and body raised stance when feeding

• Vector of huanglongbing disease

Photo: S.P. Van Vuuren, Citrus Research International

3262744475795108 5591

4

Asian citrus psyllid Diaphorina citri All

• Adult 4 mm long with a mottled brown body and greyish-brown legs. It is covered with a whitish, waxy secretion which makes it look dusty

• Wings have dark edging with a pale gap near the tip • The antennae are pale brown with black tips • Adults typically adopts a head down and body raised stance when

feeding • Vector of huanglongbing disease

Photo: David Hall, USDA Agricultural Research Service, Bugwood.org

42543475795108 5591

5CITRUS

5

Brown citrus aphidToxoptera citricida All

• Winged aphids, oval, 1-2.6 mm in length with a black but not shiny body. The wings are clear

• Two spine-like projections are present at the rear of the body as well as a short ‘tail’

• The three segments closest to the head are black

Photo: Florida Division of Plant Industry, Florida Department of Agriculture and Consumer Services, Bugwood.org

567464748101103106 91

6


• Adult wingless aphids are oval, 2-3mm in length and shiny black with two spine-like projections towards the rear

• Nymphs are dark reddish-brown. Squashing the aphid on a white surface produces a red colour which distinguishes it from the similar looking black citrus aphid

• “Knees” of all three pairs of legs are very dark

Photo: Paul Choate, Department of Entomology, University of Florida Agriculture and Consumer Services, Bugwood.org

657464748101103106 91

7

Brown citrus aphid Toxoptera citricida All

• Adult winged and wingless aphids are found in clusters on young shoots and on the underside of leaves

• Sooty mould can develop on honey dew excreted • Vector of the Citrus Tristeza Virus

Photo: Scot Nelson, University of Hawaii, Flickr.com

756464748101103106 91

8

Green citrus aphid Aphis spiraecola All

• Winged forms are oval shaped 1.2-1.7mm long with clear wings• The head and middle body segment (thorax) are dark brown• The abdomen (bottom) is pale green with dusky lateral patches on

each segment. Two dark spine like projections occur at the base of the abdomen

Photo: Spirea aphids; S. Joshi and J. Poorani. Aphids of Karnataka, www.aphidweb.com

89104791101103106 48


9


• Adult wingless aphids are oval, 1.2 -1.7mm in length with two black spine-like projections at the rear of the body

• The body is a uniform yellow, to yellowish green colour

Photo: Spirea aphids; S. Joshi and J. Poorani. Aphids of Karnataka, www.aphidweb.com

98104791101103106 48

10


• Adults found in clusters on shoots and the undersides of leaves • Feeding may cause yellowing, curling, crinkling and distortion of

young leaves and in heavy infestation, leaves can be reduced in size and die prematurely

• Sooty mould develops on honey dew • Vector of the Citrus tristeza virus

Photo: Whitney Cranshaw, Colorado State University, Bugwood.org

10894791101103106 48

11

Citrus leaf miner Phyllocnistis citrella All

• Adult moth 2 mm in length. Body is silvery white with black and tan makings

• The head has thread-like antennae • A prominent black spot is noticeable at the tip of each forewing • The hind wings appear feathery because of long wing scales

Photo: Copyright (c) 2015 Regents of the University of California

114272

12

Citrus thrips Scirtothrips aurantii All

• Adult citrus thrips are tiny orange-yellow cigar shaped insects (0.7 to 1 mm in length), with fringed wings

• The larvae do the most damage and are about the same size as adults, but are wingless

• They feed actively on tender leaves and fruit, especially under the sepals of young fruit

Photo: Joseph Morse, University of California Riverside, Bugwood.org

1289

7CITRUS

13

Black tea thripsHeliothrips haemorrhoidalis All

• Adults are tiny blackish-brown, cigar-shaped insects (1 - 1.7 mm in length) with white legs

• The wings are fringed and folded back over the thorax and abdomen at rest

• The larvae (inset) have the same body shape as adults, but are wingless• Larvae are initially whitish with red eyes but turn yellowish with maturity

Photos: 1 – Whitney Cranshaw, Buwood.org 2 – Lyle Buss, Department of Entomology and Nematology, University of Florida

13

2

1

6514

Citrus blackfl y Aleurocanthus woglumi All

• Small (approx. 2mm long) black winged insect. Lighter markings on the wings appear to form a band across the insect

• The body is orange to red initially darkening to dark-grey in a few hours. The legs are whitish with pale-yellow markings

• The insect is covered with a fi ne wax powder which gives it a slate blue appearance


141531404791

15

Citrus blackfl y Aleurocanthus woglumi All

• Adults and nymphs found on underside of leaves • Leaves may have chlorotic patches • Accumulation of sticky honeydew encourages the development of

black sooty mould giving the foliage a black appearance

Photos: Florida Division of Plant Industry Archive, Florida Department of Agriculture and Consumer Services, Bugwood.org

151431404791

16

Citrus whitefl y Dialeurodes citri All

• Small (2 mm long) insect with a creamy-yellow body and white wings• Winged adult insects are seen almost exclusively on the underside

of the leaves and fl y when disturbed• Adults lay eggs at random unlike other citrus-feeding whitefl ies

which lay eggs in patterns

Photo: Lyle Buss, University of Florida, Bugwood.org

1617244791


17


• Adults and nymphs found on the underside of leaves. Adults fl y when disturbed

• Leaves may be distorted • Sooty mould develops on the honeydew excreted by the insect • The whole canopy can become completely black in heavy infestations

Photo: Carmelo Rapisarda

1716244791

18

Red spider mitePanonychus citri All

• Adults are tiny (about 0.5 mm long), oval, dark red, insect-like creatures that are just visible with the naked eye inset (2)

• Long, white bristles arise from bumps on the back and sides of the mite (1)

Photo: 1 – Jack Kelly Clark, Copyright (c) 2014, The Regents of the University of California 2 – Rob Reeder, CABI

18

1

2

41

19

False spider mite Brevipalpus phoenicis All

• Adults are tiny insects less than a 0.3 mm in length• They are fl at, oval, and have a dark green to red-orange colour• Two pairs of legs extend forward and two extend backwards• No webbing is produced• Vector of citrus leprosis virus

Photo: Patrick Marquez, USDA APHIS PPQ, Bugwood.org

196066747576102

20

Cottony cushion scale Icerya purchasi All

• Nymphs are tiny (<1mm long), mobile with red bodies, black legs and antennae

• The body has a sparse covering of hairs• Nymphs develop a light-yellow cottony substance on their backs,

which becomes denser with age

Photo: Lorraine Graney, Bartlett Tree Experts, Bugwood.org

2036374791

9CITRUS

21

Brown soft scale Coccus hesperidum All

• The female scale body is fl at and oval, 2.5-4 mm long, brown to yellowish in colour with brown stippling

• Adults retain their legs but do not move when disturbed

Photo: Whitney Cranshaw, Colorado State University, Bugwood.org

2122304791

22

Brown soft scaleCoccus hesperidum All

• Soft scales are found in large numbers on stems leaves and fruits• Young citrus trees can be killed by high populations of scale. In

older trees feeding results in reduced tree vigor, twig dieback, reduced yields and lower fruit grades

• Sooty mould grows on excreted honey dew causing reduction of productivity and premature leaf fall

Photo: Phil Taylor, CABI

2221304791

23

Soft green scale Coccus viridis All

• The scale body is a fl at oval, 3 mm long. It has a glossy pale green colour with a black irregular U-shaped internal marking

• The front end is rounded with two marginal black eye spots (seen with a hand lens). The rear end has a distinctive groove

• Soft scale adults seen mainly on leaves, but also on twigs and fruits

Photo: United States National Collection of Scale Insects Photographs Archive, USDA Agricultural Research Service, Bugwood.org

23304791

24


• Nymphs are fl at, elliptical, scale-like insects, closely attached to the underside of a leaf

• The bodies are see through making them diffi cult to see against the green of the leaf

• Pupae (pictured) are similar but are thickened with eye spots that may show through the pupal skin

Photo: Florida Division of Plant Industry , Florida Department of Agriculture and Consumer Services, Bugwood.org

2416174791


25


• Psyllid nymphs are yellowish-orange in colour with fl attened, oval bodies

• The wing pads are prominent, especially in the later instars• Eyes and antennae are easily seen compared with whitefl y nymphs

and a fi ne fringe of hears surrounds the fi nal body segment


25443475795108 5591

26


• Psyllid nymphs are yellowish-orange in colour with a fl attened, oval body

• The wing pads are much smaller than D. citri • Advanced nymphs have two dark abdominal spots • There is a fringe of fi ne white fi laments around the whole body,

including the head

Photo: Peter Stephen, Citrus Research International, Bugwood.org

2632744475795108 5591

27

African citrus psyllidTrioza erytreae All

• The presence of small pit galls on young leaves can indicate presence of the psyllid

• The nymphs are frequently found on the underside of the leaf within the pit formed by the distortion of the leaf

Photo: Peter Stephen, Citrus Research International

2732644475795108 5591

28

Chaff scale Parlatoria pergandii G-Le-Li-M-O-P

• The scale covering is rounded to oblong, 1 to 2 mm in length and very fl at, brownish to grayish in colour

• The female body, eggs, and crawlers are purple• Immature and male scales resemble the female, but are smaller in

size and more elongate

Photo: Charles Olsen, USDA APHIS PPQ, Bugwood.org

283088

11CITRUS

29

Circular scaleChrysomphalus aonidum G-Le-Li-O-P

• Adult females are fl at to slightly domed, circular up to 2 mm in diameter • The armour is made up of three concentric rings • The main body is dark-purple to reddish-brown with paler margins.

Each scale has a raised, off-centre point which is surrounded by a pale brown disc

• The insect beneath the scale is yellow and up to 1.7 mm long

Photo: Lorraine Graney, Bartlett Tree Experts, Bugwood.org

293088

30

Soft & armoured scale damage Many spp. All

• Adult scale insects can be present on all plant parts • External feeding may cause yellowing of leaves followed by leaf

drop, poor growth, dieback of branches, fruit drop, and blemishes on fruits

• Leaves may dry when heavily infested and young trees may die • Sooty mould grows on excreted honey dew causing reduction of

productivity and premature leaf fall

Photo: Dennis Navea, ControlBest, Bugwood.org

30282932358891 47

31

Citrus blackfl yAleurocanthus woglumi All

• The nymphs are oval, brown disk shaped insects about 0.5 mm long. Later instars are back bodied with stout spines.

• The pupal case (pictured) is shiny black with dark dorsal spines and is surrounded by a white fringe of waxy secretion


311415404791

32

California red scale Aonidiella aurantii G-Le-Li-M-O-P

• Adult females are circular, fl attened, about 1.5-2 mm in diameter• The scale is made of two discs a light coloured outer and darker

and harder central disc• The scale is reddish in colour as a result of the body of the female

showing through the scale covering

Photo: Dennis Navea, ControlBest, Bugwood.org

323088


33

Fig Wax scale (1) Ceroplastes rusci, (2) C. destructor G-Le-So

• Females are wingless 4-5 mm in length. The body is oval or pentagonal and globular in shape

• Body is reddish-brown, covered with a thick red-tinged, beige, or grayish-white wax covering

Photos: 1 – ICAR-National Bureau of Agricultural Insect Resources 2 – Chicquita Rajawali, projectnoah.org

33

2

1

3047 349134

Wax scales Ceroplastes spp. G-Le-So

• Adults mainly on leaves, but also on twigs and fruits • Black sooty mould grows on excreted honey dew • Infestation results in reduced vigour and growth of the plant • Heavy infestation may cause chlorotic spotting, wilt and dieback

Photo: Mourad Louadfel, Bugwood.org

34304791 33

35

Citrus snow scaleUnaspis citri G-Le-Li-M-O-P-So

• Adult females are up to 2.25 mm long, mussel or oyster-shell shaped, brown or brown-black with a lighter coloured margin. There is often a distinct ridge down the back

• The male scales are smaller and develop a white armour. The armour is elongate oval in shape with three ridges. One prominent central ridge and two marginal ridges

Photos: Lisa Ames, University of Georgia, Bugwood.org

3588 30

36

Cottony cushion scaleIcerya purchasi All

• Adult females are wingless, 7-9 mm in length, but with egg case can appear 10-15 mm

• Adult female bodies are reddish-brown to yellow with black legs. The body is covered with thick white or cream-coloured wax

• Elongated white egg cases with fl uted ridges project from the body • White rods of wax protrude from the edges of the body

Photo: Sturgis McKeever, Georgia Southern University, Bugwood.org

3620374791

13CITRUS

37

Cottony cushion scale Icerya purchasi All

• Adults found in clusters on stems and leaves • Production of honeydew leads to the growth of sooty mould• Sap depletion may cause wilting, leaf drop, dieback and stunted growth

Photos: Mourad Louadfel, Freelance, Bugwood.org

3720364791

38

MealybugsPlanococcus citri G-Le-M-O-P-So

• Females are wingless, oval, fl attened insects approx. 1-3 mm in length. The body is segmented, yellow in colour, and coated with white wax

• P. citri has a characteristic faint grey stripe down their backs • Short waxy fi laments can be seen around the margins of the body

Photo: Charles Olsen, USDA APHIS PPQ, Bugwood.org

38394791

39

MealybugsPlanococcus citri G-Le-M-O-P-So

• Adults found in clusters on shoots leaves and fruit • Sooty mould grows on excreted honeydew causing reduction of

productivity and premature leaf fall • Heavy infestation, may cause dropping of young fruits and general

wilt of young plants

Photo: United States National Collection of Scale Insects Photographs Archive, USDA Agricultural Research Service, Bugwood.org

39384791

40

Citrus Blackfl yAleurocanthus woglumi All

• Eggs are pale yellow and laid in a characteristic spiral on the underside of young leaves

• Eggs laid in batches of 35-50

Photo: Florida Division of Plant Industry, Florida Department of Agriculture and Consum-er Services, Bugwood.org

401415314791


41

Red spider mite Brevipalpus phoenicis All

• Stippling (fi ne grey/white feeding marks) mainly on the upper surface of the leaf

• Feeding marks merge into spots resulting in a pale ‘slivery’ appearance. Little or no webbing seen

• Eventually, leaves may drop and twigs die back

Photo: 1 – Scot Nelson, University of Hawaii, Flickr.com 2 – Robert Reeder, CABI

41

1

18

2

42

Citrus leaf miner Phyllocnistis citrella G-Le-Li-M-Mx-O

• Leaf distortion (curling) caused by the serpentine (S-shaped) tunnels • Larval excrement forms a thin, central frass trail within the mine • Mature larvae pupate within the mine, rolling the edge of the leaf

and protecting the pupa with silk

Photo: Whitney Cranshaw, Bugwood.org

421172

43


• Nymphs feed exclusively on young leaves and shoots excreting white strands of wax and honeydew

• Stunting and twisting of young shoots causes distortion of the growing points

• Leaves might be covered of with sooty mould and drop prematurely • There are no galls or pits formed on the leaves

Photos: INRA-Bordeaux Archive, Institut national de la Recherche Agronomique, Bugwood.org

43425475795108

44


• Stunting and twisting of young shoots causing distortion of the growing points

• Young leaves may be yellow and pitted • Leaves might be covered of with sooty mould, and drop

prematurely

Photo: Peter Stephen, Citrus Research International

4432627475795108

15CITRUS

45

Citrus scab Elsinoë fawcettii G-Le-M-So

• Leaves can become misshapen, stunted or puckered • Raised corky pustules on leaf surface

Photo: 1 – Phil Taylor, CABI 2 – Jeffrey W. Lotz, Florida Department of Agriculture and Consumer Services, Bugwood.org

45

1

5880

2

46


• Feeding may cause yellowing, curling, crinkling and distortion of young leaves, and in heavy infestation, leaves can be reduced in size and die prematurely

• Sooty mould develops on excreted honeydew

Photo: A.A. Seif, ICIPE

465674748101103106

47

Sooty mould Many species (e.g. Capnodium citri) All

• Fungal growth caused by the accumulation of honeydew from different insects

• The photosynthetic area of the leaves is reduced and leaves die prematurely

• Sooty mould is external and can scratched off with the fi nger nail

Photo: Elizabeth Asteraki, CABI, SEARC

47345678910141516172021222324252627313334

363738394043444691

3048

Citrus tristeza virus CTV All

• The seedling yellowing syndrome of CTV cause dwarfi ng and general chlorosis of leaves


4856746101103106


49

False codling moth Thaumatotibia leucotreta All

• The caterpillar always has a distinct brown head capsule • When young it is white to cream with dark spots • The full grown caterpillar is about 15 mm long, bright red or pink

Photo: Marja van der Straten, NVWA Plant Protection Service, Bugwood.org

495197

50

Orange dog fl y Papilio demodocus All

• Caterpillars can do considerable damage to leaves of young plants • Young caterpillars are brownish with white patches and look like

bird droppings • Fully grown caterpillars are about 4.5 cm long green with light

markings and eye-like spots towards the head of the body. • When disturbed, mature caterpillars can infl ate a forked, orange

organ from behind their heads

Photos: 1 – Chazz Hesselein Alabama Cooperative Extension System, Bugwood.org. 2 – Robert Reeder, CABI

50

12

52

51


• Adult moths are small (7-8 mm long; 15-20 mm wingspan) • Both sexes have variegated brown and grey forewings with a white

spot in the centre, while hindwings are light brown to grey • Antennae are thin and multi-segmented with tiny hairs on each segment

Photo: Marja van der Straten, NVWA Plant Protection Service, Bugwood.org

514997

52

Orange dog fl y Papilio demodocus All

• Large butterfl y with a wingspan of about 9-11 cm • The butterfl y is black with yellow bands and spots on wings • Hind wings have no tails

Photo: David Cappaert, Michigan State University , Bugwood.org

5250

17CITRUS

53

Abiotic Zinc defi ciency All

• Chlorosis between veins • Leaves become smaller and narrower • Appears fi rst on new foliage uniformly throughout the tree, and

remain as it matures

Photo: Eric Boa, CABI

53 54

Citrus stubborn disease Spiroplasma citri All

• Leaf symptoms are variable but include mottling of leaves resembling nutritional defi ciencies

• Leaves can be small with an upright growth habit • Shortened stem internodes leading to bunchy-type growth

Photo: J.M. Bové, INRA Centre de Recherches de Bordeaux, Bugwood.org

5496105

55

Huanglongbing (Citrus greening) Candidatus Liberibacter spp. All

• Blotchy mottle (different pattern of yellowing on right an left sides), of the midrib

• Infected leaves may be thicker and show raised corky veins (inset 2) • Early stages restricted to a few shoots randomly arranged in the canopy

Photos: Robert Reeder, CABI

55

Raised corky veins

342526274344579510856

Abiotic Iron defi ciency All

• Yellowing between the small, darker green veins • This net-vein pattern occurs primarily in young leaves of the new

fl ushes of leaves • Top left healthy leaf

56

Photos: Dr Prakash Kumar & Dr Manoj Kumar Sharma


57


• Yellow shoots in just one section of the tree is usually the fi rst symptom, following by a progressive yellowing of the entire canopy

Photo: Florida Division of Plant Industry Archive, Florida Department of Agriculture and Consumer Services, Bugwood.org

575595108 342526274344

58


• Pink to cream slightly raised pustules mostly along the main veins on the lower leaf surface

• With age the pustules become more defi ned, warty and crack • Young lesions easily confused with citrus canker • Affected leaves become stunted, malformed, wrinkled or puckered

Photo: Hilda Gomez, USDA

584580

2

59

Citrus canker Xanthomonas axonopodis pv. citri Mostly G-Le-Li-Mx

• Young spots are small blisters surrounded by a yellow ring • Older spots turn tan to brown, and have a water-soaked margin

surrounded by a yellow ring • The lesion becomes corky, with raised concentric circles seen on

the underside of the leaf

Photo: 1 – Rob Reeder, CABI 2 – Dr Prakash Kumar & Dr Manoj Kumar Sharma

59

1 2

7710060

Citrus leprosis virus CiLV G-Le-M-Mx-O-So

• Lesions are round with a dark-brown central mite feeding spot. They are visible on both sides of the leaf

• The feeding spot is surrounded by a chlorotic halo with 1-3 concentric rings

• Lesions may join to form larger irregular lesions

Photos: Carlos Amadeu Leite de Oliveira, Universidade Estadual Paulista, Bugwood.org, Hilda Gomez, USDA, Bugwood.org

601966747576102

19CITRUS

61

Areolate leaf spotThanatephorus cucumeris G-M-O

• Light coloured necrotic areas with dark concentric rings form on leaves • Chlorotic halos form around the lesions and the leaves drop off the plant

Photo: Shamela Rambadan, CABI

61 62

Melanose Diaporthe citri All

• Numerous, small, reddish-brown raised spots give the leaf a rough texture

• Early spots on leaves are surrounded by a yellow halo. The halo quickly disappears leaving only small corky pustules

Photos: 1 – Esther Serrano USDA, 2 – Scot Nelson, University of Hawaii, Flickr.com

62

1 2

8687

63

Septoria spot Septoria citri Mostly G-Le-O

• Raised, black spots (1-4 mm in diameter) are produced on the leaf surface

• Pin-head sized black dots (fruiting bodies) develop in the spots, especially following leaf drop

• The spots turn dark brown with age and have dark margins. • In wet conditions the disease may cause severe leaf drop in the

lower portion of the tree

Photo: Jim Adaskaveg, Copyright (c) 2014 The Regents of the University of California

6381

64

Greasy spot Mycosphaerella citri All

• First appears as pale yellow slightly raised lesions on the underside of the leaves

• Lesions darken with age and eventually become brown to black

Photo: Elizabeth Asteraki/CABI SEARC

6484


65

Black tea thrips Heliothrips haemorrhoidalis All

• Feeding by the adults and larvae causes chlorotic spots. Severely infested leaves become papery

• Tiny oily drops of frass can be seen on the leaf surface with a hand lens • Heavy infestation results in defoliation

Photos: Whitney Cranshaw, Bugwood.org

6513

66

False spider mite Brevipalpus phoenicis All

• Numerous and close chlorotic spots around feeding marks, that merge into larger brown patches

• Production of tiny woody galls at the nodes preventing the sprouting of buds.

• Heavy infestation can result in leaf fall, shoots distortion and dieback and a reduction in fruit yield

• Vector of citrus leprosis virus

Photo: Patrick Marquez, USDA APHIS PPQ, Bugwood.org

661960747576102

67

Brown spot Alternaria alternata Mostly G-Le-T

• Initial spots are small brown to black with prominent yellow halos • Lesions expand into irregular or circular necrotic areas which can

involve large portions of the leaf • Necrosis and chlorosis can occur along the veins extending from

lesions • Lesions are fl at and visible on both sides of the leaf • Older lesions become brittle and paper-like in the middle

Photo: Esther Serrano, USDA, GST

6785

68

Anthracnose Glomerella cingulata All

• Light tan circular spots with a prominent purple margin develop on the leaves

• Fruiting bodies of the fungus (tiny black fl ecks) are sometimes seen within the spots

• Plants injured by various environmental factors or heavy infestations of spider mites are more susceptible to disease

Photo: Paul Chaloux, USDA

6883

21CITRUS

69

Citrus angular leaf spot Pseudocercospora angolensis All

• Flat, circular, leaf spots with yellow halo on older leaves • Occasionally the centre of the lesion falls out, creating a shot-hole effect • Spots, on younger leaves, can coalesce to cause generalized

chlorosis, followed by leaf drop

Photo: Robert Reeder, CABI

6973

70

Lime anthracnose Colletotrichum acutatum Mx

• Necrotic spots form usually towards the margins of the leaves, the centre of the spot may fall out giving a shot-hole. Spots are brown and often surrounded by a yellow halo.

• In severe infections shoot tips may die back and leaf distortion occurs


70

Shot hole

7899

71

Black spot Guignardia citrocarpa All except Li-So

• Leaf spots are rarely seen in well managed groves • Young lesions are small, reddish, and slightly raised. A yellow halo

can be associated with the lesions • Older lesions become sunken with grey centres and a dark brown border • All commercial citrus species are susceptible, except for sour

orange and Tahiti lime

Photo: Mongi Zekri, University of Florida IFAS extension

7182

72

Citrus leaf miner Phyllocnistis citrella G-Le-Li-M-Mx-O-So

• ‘Snake like’ tunnels are formed due to the internal feeding of larvae. The larvae and frass can be seen inside the leaf when held up to the light

• The leaf can become deformed (rolled or folded) and fall from the plant • Older leaves are not susceptible

Photo: 1 – Automania, 2 – NBAI

72

1 2

1142

2


73

Citrus Angular leaf spot Pseudocercospora angolensis All

• Spots are usually circular, discrete or coalescent, mostly up to 10 mm in diameter.

• The spots are hard, fl at, or sometimes raised. The centre of the spot is brown and cracked.

• Spots are surrounded by a prominent yellow halo • On young fruits, infection often results in raised tumour-like

growths surrounded by a yellow halo

Photo: Rob Reeder, CABI

7369

74


• Older lesions on green fruit appear as fl at or slightly depressed spots with a necrotic centre and surrounded by a yellow halo

• The spots are confi ned to the rind and sometimes gum is seen oozing from the lesion

• With abundant lesions dropping of fruit and leaves can occur

Photos: Hilda Gomez, USDA

741960667576102

75

Citrus leprosis virusCiLV G-Le-M-Mx-O-So

• Lesions on green fruit initially appear as yellow circles with a central mite feeding spot

• Over time the lesions becomes brown or blackish

Photo: Ron Brlansky, University of Florida Citrus Research and Education Center

751960667476102

76

Citrus leprosis virusCiLV G-Le-M-Mx-O-So

• Over time the lesions becomes brown or blackish • Lesions appear as fl at or slightly depressed spots with a necrotic

centre, confi ned to the rind • Infected fruit tend to change colour early and become susceptible

to various rots

Photo: Ron Brlansky, University of Florida Citrus Research and Education Center

761960667475102

23CITRUS

77


• Young lesions are raised, blister-like, tan, surrounded by yellow halos, depending on fruit maturity

• Older spots are circular dark brown to black with brown to black sunken, corky centres

Photo: Jeffery.W lotz, Florida department of Agriculture and Consumer Services, Bugwood.org

7759100

78


• Infection of young fruit usually results in premature fruit drop • Late infections produce large raised corky lesions that are often

deep and accompanied by fruit distortion


787099

79

Broad mite Polyphagotarsonemus latus G-Le-Li-M-O-So

• Feeding results in scarred tissue that cracks as fruit grows (shark skin pattern)

• The toxic saliva of the mite may induce growth distortions and stunting

Photos: Scot Nelson, University of Hawaii, Flickr.com

79 80


• Fruit spots are circular to irregular raised corky areas or crater-like outgrowths

• Initially the scabs are pink to light brown, darkening to dirty grey with age


804558


81

Septoria spot Septoria citri Mostly G-Le-O

• Small, superfi cial, light tan to reddish brown pits (1-2 mm in diameter) develop on the fruit

• Older lesions are larger, darker and extend deeper into the rind • Pin-head sized black dots (fruiting bodies) develop in the lesions • Lesions may appear in the form of “tear stains” patterns that are

more evident on ripe fruit

Photo: Jim Adaskaveg, Copyright (c) 2014 The Regents of the University of California

8163

82

Black spot Guignardia citrocarpa All except So

• Fruit spots are small, round, sunken with grey centres and brick-red to chocolate brown margins

• Green halos are often seen around the lesions • Fungal bodies appear as slightly raised black dots in the centre of

lesions. They usually appear as the fruit begins to colour

Photo: Robert Reeder, CABI

8271

83

Anthracnose Glomerella cingulata All

• Fruit spots are brown to black spots 1.5 mm or greater diameter • Tear staining can occur on the fruit (liner black marks where the

spores have run off the fruit) • Under humid conditions, the spore masses are pink/orange, but if

kept dry, appear brown to black • The decay is usually fi rm and dry but if deep enough can soften the fruit

Photo: Paul Chaloux, USDA

8368

84

Greasy spot Mycosphaerella citri All

• Minute black spots form on the fruit surface with the surrounding area retaining a green colour longer

• The black spots can occur in patches or involve large areas of the fruit surface.

• On severely affected fruit, lesions join and become sunken to form large pinkish-brown areas

Photo: Tim Gottwald, Bugwood.org

8464

25CITRUS

85

Brown spot Alternaria alternata Mostly G-Le-T

• Young lesions are slightly sunken dark spots with yellow halos • Corky ‘pimple-like’ structures erupt from the fruit surface. The pimples

later drop off, forming craters or pockmarks on the fruit surface • Fruit drop is common, especially if infection has occurred shortly

after petal fall • The lesions can crack around the outer edge, giving a moat-like

appearance

Photo: Jeffery.W lotz, Florida department of Agriculture and Consumer Services, Bugwood.org

8567

86

Melanose Diaporthe citri All

• Infections during late stages of fruit development produce small discrete pustules.

• The small circular spots may be distinguished from mite damage as they feel like sandpaper

Photos: Scot Nelson, University of Hawaii, Flickr.com

866287

87

MelanoseDiaporthe citri All

• ‘Tear-stain’ patterns form when the spores are washed over the fruit surface in water or dew. Early infections (soon after petal fall) result in large pustules that may join to form extensive areas. These often crack to produce a pattern described as “mudcake melanose”


876286

88

Armoured scale Chrysomphalus spp. All

• Scale insects adhere to the fruit surface, but can be scratched off with a fi nger nail

• Feeding may cause small discoloured spots in the skin. Internal fruit quality is not impaired


882829303235


89

Citrus thrips Scirtothrips aurantii All

• Thrips feeding causes brown circular rings of russet marks on the rind of the fruit

• Feeding marks are most prominent on the top of the fruit where it attaches to the plant

Photo: Eric Boa, CABI

8912

90

Citrus rust mite Phyllocoptruta oleivor All

• Fruit skins turn silvery, reddish, or black. On grapefruit and lemons the feeding results in a silvered or ‘sharkskin’ appearance.

• Rind of silvered fruit is thicker than on undamaged fruit, and silvered fruit loses water faster than undamaged fruit

Photo: Don Ferrin, Bugwood.org

90

91

Sooty mould Many species (e.g. Capnodium citri) All

• Fungal growth caused by the accumulation of honeydew from different insects, but not damaging the fruit

• In heavy infestations it may cause a reduction in fruit size and quality

Photo: Elizabeth Asteraki/CABI SEARC

91345678910141516172021222324252627303334

363738394043444647

3192

Sun scald NA All

• Circular to irregular brown sunken spots develop on exposed fruits

Photo: Gerald Holmes, California Polytechnic State University at San Luis Obispo, Bugwood.org

92

27CITRUS

93

Stalk end rot Alternaria citri Le-M-O

• Internal rotting that can expand to the fruit surface in advanced stages • The infected tissues darken, soften and their surfaces are covered

in a thin coating of fungus • Fruit change colour prematurely • Premature dropping of fruits

Photo: AgrEvo

93 94

Brown rot of citrus fruit Phytophthora citrophthora All

• Small dark spots develop on fruits near the ground, increase in size and turn various shades of greenish-brown

• Brown rot eventually develops, and white fungal growth can occur on the surface of fruit in storage. Bark and trunk symptoms

Photo: Anna L. Snowdon

94104

95


• Small, lopsided and poorly coloured fruit • Seeds blackened and aborted when severe fruit drop

Photo: Rob Reeder, CABI

955557108

96


• Fruit symptoms are variable but include small size and lopsided fruit. • Fruit drop is common but extent depends on horticultural

management. • Internal fruit development can be imperfect with thinner rind on

one side and thicker on the other • Severely-affected fruit can lack taste or be bitter fl avoured • Seeds produced are often aborted

Photo: J.M. Bové, INRA Centre de Recherches de Bordeaux, Bugwood.org

9654105


97


• Hole seen in the rind of the fruit • The skin around the point of penetration develops a brown discoloration • Dry frass on the outside of a fruit is an indication of the presence

of a larva

Photos: Rob Reeder, CABI

975149

98

Fruit fl y Damage Ceratitis capitate, Bactrocera invadens All

• Attacked fruit usually show punctures (2) made by females while laying eggs

• Necrosis occurs around the punctures and fruit becomes soft and colours prematurely

• Fruits drop off trees and begin to rot • Creamy white maggots about 7-8 mm long are found inside the

fruit. The maggots of both fruit fl iy spp. will jump on touch

Photos: 1 – Florida Division of Plant Industry , Florida Department of Agriculture and Consumer Services , Bugwood.org, 2 – Rob Reeder, CABI

98

1

12

2

99


• Fruits may become distorted, misshapen and crack through the spots

Photo: Phil Taylor, CABI

997078

100


• Canker lesions develop as light yellow/brown, raised, spongy patches on the surface of leaves, twigs and fruits

Photo: M.Goto, Bugwood.org

1005977

29CITRUS

101

Citrus tristeza virus Citrus tristeza virus All

• Stem pitting syndrome: deep pits in the trunk twigs and stem when bark is removed

• Thin canopy, fewer fruits of reduced size and quality


10156746 848103106

102


• Round to oval shaped, grey/brown lesions develop on young twigs • As they age the lesions become corkier and cause the bark to

fl ake away • Lesions may merge when present in large numbers resulting to the

death of the twigs and dieback


102196066747576

103

Citrus tristeza virus Citrus tristeza virus All

• Decline syndrome: in slow decline, many small conical pits on the face of the bark surface (honeycombing). Tree affected by quick decline lack honeycombing

Photo: L. Navarro, Instituto Valenciano de Investigaciones Agrarias, Bugwood. org

10356746 848101106

104

Phytophthora rot Phytophthora spp. All

• Symptoms of foot and crown rot are seen at the bud union and below the soil line

• The base of the trunk appears water-soaked and a reddish-brown to black necrotic area develops under the bark

• The bark cracks longitudinally and gum oozes from the trunk (2) • In advanced stages, severe yellowing and shedding of the foliage. • Roots turns soft and appear water-soaked. Fibrous roots slough off

their cortex, leaving only the white thread-like inner tissue behind

Photos: 1 – JH Graham CREC 2 – A. Vincent IVIA

104

1

2

94


105


• Irregular (off-season) fl owering results in various-sized fruit with different maturities. Fruit production can be greatly reduced

• Shortened stem internodes result in bunchy-type growth • Mildly-infected trees may be normal in size, but severely-affected

trees are stunted with a thin canopy, often with a fl attened top and tip dieback

• Symptoms on mildly-infected trees are often localized within a sector of a tree

Photo: Ray Yokomi, USDA, ARS, Parlier, CA

1055496

106

Citrus tristeza virus CTV All

• Slow decline is characterised by wilting and chlorosis of the canopy • Small fruits develop that persist after the death of the tree


10656746 848101103

107

Citrus root nematode Tylenchulus semipenetrans All

• Symptoms develop slowly. The leaves of infected trees are smaller and are commonly chlorotic

• Wilting is more pronounced in infected trees during conditions of water stress

Photo: Nicholas S. Sekora, University of Florida

107109

108


• Trees are sparsely foliated with extensive branch dieback and reduced size

Photo: Matthew Weinert/AQIS

108555795 343537 364344

31CITRUS

109

Citrus root nematode Tylenchulus semipenetrans All

• Heavily infected fi brous roots (1) appear thicker and more irregular than healthy roots (2) due to soil sticking to the egg masses on the root surface

• Infected roots decay because of penetration and feeding of nematodes and secondary infections.

• Heavy infections result in the outside root surface being easily removed

Photo: Gerald Holmes, California Polytechnic State University at San Luis Obispo, Bugwood.org

109 107

Plantwise is a global programme, led by CABI, to increase food security and improve rural livelihoods by reducing crop losses. Working in close partnership with relevant actors, Plantwise strengthens national plant health systems from within, enabling countries to provide farmers with the knowledge they need to lose less and feed more. This is achieved by establishing sustainable networks of local plant clinics, run by trained plant doctors, where farmers can find practical plant health advice. Plant clinics are reinforced by the Plantwise knowledge bank, a gateway to online and offline actionable plant health information, including diagnostic resources, pest management advice and front-line pest data for effective global vigilance.


KNOWLEDGE FOR LIFE

AfricaGhana CABI, CSIR Campus No. 6 Agostino Neto Road Airport Residential Area P. O. Box CT 8630, Cantonments Accra, Ghana

T: +233 (0)302 797 202 E: [email protected]

Kenya CABI, Canary Bird, 673 Limuru Road, Muthaiga, PO Box 633-00621 Nairobi, Kenya

T: +254 (0)20 2271000/20 E: [email protected]

AmericasBrazil CABI, UNESP-Fazenda Experimental Lageado, FEPAF (Escritorio da CABI) Rua Dr. Jose Barbosa de Barros 1780 Fazenda Experimental Lageado CEP:18.610-307 Botucatu, San Paulo, Brazil

T: +5514-38826300 E: [email protected]

Trinidad & Tobago CABI, Gordon Street, Curepe Trinidad and Tobago

T: +1 868 6457628 E: [email protected]

USA CABI, 745 Atlantic Avenue 8th Floor, Boston, MA 02111, USA

T: +1 (617) 682-9015 E: [email protected]

AsiaChina CABI, Beijing Representative Office Internal Post Box 56 Chinese Academy of Agricultural Sciences 12 Zhongguancun Nandajie Beijing 100081, China

T: +86 (0)10 82105692 E: [email protected]

India CABI, 2nd Floor, CG Block, NASC Complex, DP Shastri Marg Opp. Todapur Village, PUSA New Delhi – 110012, India


Malaysia CABI, PO Box 210, 43400 UPM Serdang Selangor, Malaysia


Pakistan CABI, Opposite 1-A, Data Gunj Baksh Road Satellite Town, PO Box 8 Rawalpindi-Pakistan


EuropeSwitzerland CABI, Rue des Grillons 1 CH-2800 Delémont, Switzerland


UK CABI, Nosworthy Way Wallingford, Oxfordshire OX10 8DE, UK


UK CABI, Bakeham Lane Egham, Surrey TW20 9TY, UK

T: +44 (0)1491 829080 E: [email protected] E: [email protected]

Contact us

citrus disorders - plantwise · front cover: hilda gomez, usda . citrus 3 contents sign or symptom...

Documents