Citrus Fruits:Photos

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Citrus Pest and Nutritional Disorder Photos






Contents

Amorphous_plugs

Amorphous plugs

The dense amorphous plugs as seen in the light microscope (R.H. Briansky)

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Bark_cracking

Bark cracking

Mild bark cracking on trifoliate orange rootstock induced by the citrus viroid lla present in "virus" source E-818 (California)

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Bark_cracking

Bark cracking

Severe bark cracking on the stem of citron 861-S-1 ubducatir okabt ubicykated wutg CEV

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Bark_scaling

Bark scaling

Classic severe bark scaling on trifoliate orange rootstock caused by CEV (California)

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Bark_scaling

Bark scaling

Classic severe bark scaling on Rangpur lime rootstock caused by CEV (Brazil) (G. Muller)

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Blight

Blight

A typical blight-affected grapefruit tree on the left with a non-affected tree on the right, in Florida

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Blight

Blight

A typical blight-affected Pera sweet orange tree on Rangpur lime rootstock in Brazil. Infected tree on the left with a non-infected tree on the right

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Blight

Blight

Field tree on the left shows symptoms of blight. This was root-grafted with roots from a five-or six-year-old blight-affected sweet orange tree in the centre. This infected source tree was transplanted between two healthy field trees. The tree on the right is the non-inoculated healthy control

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Blight

Blight

Showing the dense amorphous plugs diagnostic for blight as observed in the scanning electron microscope

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Browning

Browning

Midvein browning (control on left)

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Browning

Browning

Petiole browning and wrinkle (control on right)

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Bud-union_abnormality

Bud-union abnormality

Bud-union crease of Valencia on rough lemon rootstock in Florida (S.M. Garnsey)

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Bud-union_abnormality

Bud-union abnormality

Bud-union crease of Palmer navel on trifoliate rootstock in South Africa. The condition is transmissible

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Bud-union_abnormality

Bud-union abnormality

Bud-union overgrowth of mandarin on Troyer citrange in the Central Valley of California. This condition is attributed to environmental conditions typical for most mandarins and tangelos in the Central Valley. Trees declind in about 15 years

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Bud-union_abnormality

Bud-union abnormality

Close-up showing brown line totally around trunk

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Bud-union_abnormality

Bud-union abnormality

Transmissible bud-union abnormality of Tomango sweet orange on rough lemon rootstock in South Africa. Cuts made into the bud-union bulge show indentation and severe staining surrounding the union

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CEV

CEV

Acorn-shaped fruit of citron induced by CEV (California). Similar acorn-shaped fruit occur on Volkamer lemon

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CEV

CEV

Classic severe symptoms of CEV in citron showing severe epinasty of leaves. A few normal control leaves are shown on the left

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CEV

CEV

Older trees of Valencia orange on trifoliate rootstock. CEV-infected trees are on the right (All CEV-infected trees show bark cracking on the trifoliate rootstock)

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CEV

CEV

The effect of CEV on tree size (California). Five-year-old trees of Valencia orange on Troyer citrange. CEV-infected tree is on the left

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CEV

CEV

Yellow blotching on stems of Troyer citrange induced by CEV (Italy). A similar yellow blotching occurs on stems of Rangpur lime

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Citrus_blight

Citrus blight:

A sweet orange tree with citrus blight on the right and a healthy tree on the left. 

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Citrus_blight_(cause_unknown)

Citrus blight (cause unknown):

This tree is showing advanced symptoms of citrus blight. Twig dieback and canopy thinning occur.  

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Citrus_blight_(cause_unknown)

Citrus blight (cause unknown):

Light yellow amorphous plugs develop in the xylem vessels of blight-affected trees and are diagnostic of citrus blight. Filamentous plugs also occur in citrus, but are not unique to citrus blight. 

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Citrus_blight_(cause_unknown)

Citrus blight (cause unknown):

A typical blight-affected grapefruit tree on the right with a non-affected tree on the left, in Florida. 

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Citrus_blight_(cause_unknown)

Citrus blight (cause unknown):

Showing the dense amorphous plugs diagnostic for blight as observed in the scanning electron microscope. 

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Citrus_blight_(cause_unknown)

Citrus blight (cause unknown):

The dense amorphous plugs as seen in the light microscope.  

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Citrus_cachexia_viroid

Citrus cachexia viroid:

A window in the trunk of a field tree of Ellendale mandarin showing severe symptoms of gumming on the bark and trunk typical of severe cachexia. Note the areas of gum in the cut-back section (Australia). 

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Citrus_cachexia_viroid

Citrus cachexia viroid:

The trunk portion of a field tree of Parson's Special mandarin as a rootstock under a grapefruit scion with the bark cut away to show the brown gum-stain. This tree was inoculated with a severe isolate of citrus cachexia viroid (Central California). 

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Citrus_cachexia_viroid

Citrus cachexia viroid:

Very severe symptom reaction on Parson's Special mandarin after the bark is completely peeled.  

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Citrus_Cachexia_viroid

Citrus Cachexia viroid

Parson's Special mandarin as a scion budded to rough lemon as the rootstock with a window cut into the bud-union showing severe symptoms in the Parson's Special mandarin. Note that the gumming occurs only in the Parson's Special mandarin and not in the rough lemon rootstock (greenhouse-grown, Riverside, California)

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Citrus_Cachexia_viroid

Citrus Cachexia viroid

The trunk portion of a field tree of Parson's Special mandarin as a rootstock under a grapefruit scion with the bark cut away to show the brown gum-stain. This tree was inoculated with a severe isolate of citrus cachexia viroid (Central California)

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Citrus_concave_gum

Citrus concave gum:

A narrow oak leaf pattern developed about the midvein in a leaf of Valencia orange. Note the strong interveinal flecking, usually the first symptom observed in leaves on plants inoculated with concave gum virus. 

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Citrus_concave_gum

Citrus concave gum:

Concavities associated with concave gum diseases in the trunk of a sweet orange tree in the field (Spain). 

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Citrus_concave_gum

Citrus concave gum:

Concentric gum rings in a cross-section of a branch. This is highly symptomatic for concave gum disease when present with trunk concavities and oak leaf pattern. 

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Citrus_cristacortis

Citrus cristacortis (cause unknown):

A typical deep pit in the trunk, with corresponding peg in the bark of a Navalina orange tree infected with cristacortis (Spain). 

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Citrus_cristacortis

Citrus cristacortis (cause unknown):

Cross section of a branch showing both cristacortis and concave gum. The concentric gum rings are associated with concave gum infection, and the pitting in the outer circumference indicates cristacortis. 

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Citrus_cristacortis

Citrus cristacortis (cause unknown):

Cross section of a branch showing the deep pits caused by cristacortis infection. 

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Citrus_cristacortis

Citrus cristacortis (cause unknown):

Typical pitting symptom of cristacortis in the trunk of both scion and rootstock. Scion is Clementine mandarin and rootstock is sour orange (Sicily). 

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Citrus_cristacortis

Citrus cristacortis (cause unknown):

When a section is cut from the bark, the typical pits and pegs are visible in the trunk and inner bark. 

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Citrus_cristacortis

Citrus cristacortis:

Chlorotic flecks and spots on the leaves of a mandarin tree infected with cristicortis.

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Citrus_exocortis_viroid

Citrus exocortis viroid:

Acorn-shaped fruit of citron induced by citrus exocortis viroid (California). Similar acorn-shaped fruit occur in Volkamer lemon 

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Citrus_exocortis_viroid

Citrus exocortis viroid:

Classic severe bark scaling on trifoliate orange rootstock caused by citrus exocortis viroid (California). 

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Citrus_exocortis_viroid

Citrus exocortis viroid:

Classic severe bark scaling on Rangpur lime rootstock caused by citrus exocortis viroid (Brazil). 

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Citrus_exocortis_viroid

Citrus exocortis viroid:

Classic severe symptoms of citrus exocortis viroid in citron showing severe epinasty of leaves. A few normal control leaves are shown on the left. 

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Citrus_exocortis_viroid

Citrus exocortis viroid:

Scaling occurring on the C-35 citrange rootstock due to presence of citrus exocortis viroid.

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Citrus_exocortis_viroid

Citrus exocortis viroid:

Sweet orange trees on C-35 citrange rootstock showing stunting due to citrus exocortis viroid.

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Citrus_grandis

Citrus grandis

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Citrus_greening

Citrus greening:

A branch on a sweet orange tree that has been infected with citrus greening. Note the small chlorotic leaves that point upright.  

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Citrus_greening

Citrus greening:

A red mandarin tree affected by the Asian form of citrus greening. The leaves are small, the canopy thins and zinc deficiency symptoms are common.  

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Citrus_greening

Citrus greening:

A typical greening-affected mandarin tree in the field (New Territories, Hong Kong).  

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Citrus_greening

Citrus greening:

Abundant greening organisms in the haemolymph of Trioza erytreae.  

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Citrus_greening

Citrus greening:

Characteristic bumps on the underside of sweet orange leaves caused by the feeding of Trioza erytreae (South Africa). 

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Citrus_greening

Citrus greening:

Diaphorina citri feeding on a young shoot and leaves of a citrus tree. Note the angular position taken by the insect when feeding (Pakistan). 

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Citrus_greening

Citrus greening:

Drawing of adults and instars of Diaphorina citri and Trioza erytreae  

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Citrus_greening

Citrus greening:

Leaves from a red mandarin tree affected by the Asian form of citrus greening.  

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Citrus_greening

Citrus greening:

The blotchy mottle symptom of citrus greening on a sweet orange leaf. This figure is of African form of greening.  

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Citrus_greening

Citrus greening:

The yellow vein symptom on a sweet orange tree affected by the Asian form of citrus greening. The yellow vein symptom is helpful to differentiate citrus greening from other chronic tree declines such as citrus blight, tristeza decline, stubborn, and citrus variegated chlorosis. 

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Citrus_greening

Citrus greening:

Typical greening of fruit. Two normal Valencia oranges surrounded by greening-affected fruit (South Africa). Note the stylar end greening and smaller fruit.  

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Citrus_impietratura

Citrus impietratura (cause unknown):

Impietratura induced gumming in albedo of a sectioned young grapefruit (Spain). 

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Citrus_impietratura

Citrus impietratura (cause unknown):

Impietratura induced spotting and gumming in the rind and albedo of Navalina oranges; note the typical green spotting on coloured fruit (Spain). 

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Citrus_leprosis_rhabdovirus

Citrus leprosis rhabdovirus:

Lesions on citrus fruit   

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Citrus_leprosis_rhabdovirus

Citrus leprosis rhabdovirus:

Leprosis on the trunk of a tree in Venezuela 

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Citrus_leprosis_rhabdovirus

Citrus leprosis rhabdovirus:

Leprosis symptoms on sweet orange fruit, young twigs, and leaf. On leaves and twigs, the lesions are first chlorotic, then become necrotic in the center. Extensive lesions on twigs causes dieback. Leaves and fruit commonly abscise on leprosis-infected trees. 

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Citrus_leprosis_rhabdovirus

Citrus leprosis rhabdovirus:

Specimen of citrus leprosis preserved at the INTA Experiment Station, Concordia, Argentina. 

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Citrus_psorosis

Citrus psorosis:

Bark scaling in a grapefruit tree caused by Citrus psorosis.

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Citrus_psorosis

Citrus psorosis:

Leaf symptoms induced by ringspot psorosis inoculated to seedling of Marsh grapefruit (California). 

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Citrus_psorosis

Citrus psorosis:

Leaf symptoms of Citrus psorosis occurring on a sweet orange plant. 

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Citrus_psorosis

Citrus psorosis:

Lesion bark blisters of psorosis-B on a twig and thorn of sweet orange (above) with the non-inoculated control below. 

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Citrus_psorosis

Citrus psorosis:

Mature ringspot-type leaf symptoms in mature leaves of Valencia orange. 

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Citrus_psorosis

Citrus psorosis:

Mature ringspot-type leaf symptoms in mature leaves of rough lemon. 

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Citrus_psorosis

Citrus psorosis:

Necrotic local lesions on Chenopodium quinoa after inoculation with a citrus ringspot strain of Citrus psorosis. 

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Citrus_psorosis

Citrus psorosis:

Psorosis shock symptoms in inoculated young seedlings of Pineapple sweet orange. The plant on the left is completely shocked. Shock remnants will remain on the plant and do not drop off. 

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Citrus_psorosis

Citrus psorosis:

Psorosis-B-induced, blister-like lesions on the underside of a sweet orange leaf. Similar lesions may be found on leaves of field trees infected with ringspot.  

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Citrus_psorosis

Citrus psorosis:

Scaly bark symptoms of psorosis-A on the trunk of a sweet orange in California.  

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Citrus_psorosis

Citrus psorosis:

Shock symptoms occurring on a Madame Vinous sweet orange indicator plant in the first growth flush after inoculation with buds from field plants infected with Citrus psorosis.

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Citrus_psorosis

Citrus psorosis:

Staining of interior wood of a branch of sweet orange infected with psorosis-A. This symptoms is diagnostic for psorosis-A when found on trees showing bark lesions. 

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Citrus_psorosis

Citrus psorosis:

Symptoms of ringspot on fruit of Clementine mandarin in Spain showing green spotting of fruit. Impietratura may be present. 

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Citrus_psorosis

Citrus psorosis:

Symptoms of ringspot psorosis on leaves and fruit of Naveline orange in Greece showing indented sunken areas on fruit. 

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Citrus_psorosis

Citrus psorosis:

The effect of temperature on symptom expression, showing variation in leaf symptoms due to the effect of the above temperature regimes. The leaf on the left is from a plant grown under the cool temperature and the leaf on the right is from a plant grown under the warm temperature regime. Both plants were inoculate with the same inoculum. 

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Citrus_tatterleaf_capillovirus

Citrus tatterleaf capillovirus

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Citrus_tatterleaf_capillovirus

Citrus tatterleaf capillovirus

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Citrus_tatterleaf_capillovirus

Citrus tatterleaf capillovirus:

Severe tatterleaf reaction induced by CTLV showing bud-union crease and fluting in the trunk of Troyer citrange rootstock with satsuma orange scion.  

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Citrus_tatterleaf_capillovirus

Citrus tatterleaf capillovirus:

Breakage and separation of a tatterleaf-infected satsuma scion from the trifoliate rootstock. Specimen at Kuchinotsu, Japan.  

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Citrus_tatterleaf_capillovirus

Citrus tatterleaf capillovirus:

Symptoms of tatterleaf in leaves of Rusk citrange inoculated with CTLV. Note deformed leaves with spots and blotches.  

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Citrus_tatterleaf_capillovirus

Citrus tatterleaf capillovirus:

Symptoms of tatterleaf in leaves of citrus excelsa from a seedling inoculated with CTLV. The non-inoculated control leaf is on the left. Note the tattered, irregular-edged leaves giving the disease its name.  

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Citrus_tatterleaf_capillovirus,

Citrus tatterleaf capillovirus, the virus produces zig zag growth of the stem and distortion of the leaves, as seen on the plant on the left.

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Citrus_tristeza_closterovirus

Citrus tristeza closterovirus:

Sweet orange tree on sour orange rootstock undergoing tristeza decline 

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Citrus_tristeza_closterovirus

Citrus tristeza closterovirus:

In addition to stem pitting of sweet orange, grapefruit, and pummelo scions, some strains of tristeza can also stem pit rootstocks which are normally considered to be tristeza-tolerant. This figure shows stem pitting in rough lemon rootstock.  

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Citrus_tristeza_closterovirus

Citrus tristeza closterovirus:

Quick decline of a sweet orange on sour orange rootstock caused by citrus tristeza virus (Israel). The sudden collapse and death of sweet orange, mandarin or grapefruit on sour orange rootstock is an indication of tristeza.  

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Citrus_tristeza_closterovirus

Citrus tristeza closterovirus:

Vein-clearing symptoms in the leaf of a Mexican lime seedling (right) as viewed from the back of the leaf into direct sunlight. Control on the left. 

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Citrus_tristeza_closterovirus

Citrus tristeza closterovirus:

Mild vein-clearing flecks induced in a leaf of Mexican lime by a mild reacting tristeza isolate. 

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Citrus_tristeza_closterovirus

Citrus tristeza closterovirus:

Vein corking symptoms on leaves of Mexican lime seedling inoculated with a very severe seedling-yellow tristeza isolate. 

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Citrus_tristeza_closterovirus

Citrus tristeza closterovirus:

Seedling-yellows reaction in two Duncan grapefruit seedlings with a non-inoculated control in the centre. Note the severe stunting in the two inoculated seedlings.  

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Citrus_tristeza_closterovirus

Citrus tristeza closterovirus:

Stem pitting in the peeled stem of (b) sour orange.  

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Citrus_tristeza_closterovirus

Citrus tristeza closterovirus:

Stem pitting on the trunk of a Pera sweet orange tree on Rangpur lime rootstock due to infection with citrus tristeza virus in Brazil. 

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Citrus_tristeza_virus

Citrus tristeza virus

Quick decline of a sweet orange on sour orange rootstock caused by citrus tristeza virus (Israel). The sudden collapse and death of sweet orange, mandarin or grapefruit on sour orange rootstock is an indication of tristeza

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Citrus_variegation_ilarvirus

Citrus variegation ilarvirus:

Symptoms of CIVV on leaves of navel orange from a tree in the field (Spain).  

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Citrus_variegation_ilarvirus

Citrus variegation ilarvirus:

Symptoms on a citron seedling showing severe epinasty, chlorotic variegation and leaf distortion induced by inoculation with CIVV (California). 

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Citrus_variegation_ilarvirus

Citrus variegation ilarvirus:

Symptoms on mature leaves of an inoculated Madame Vinous sweet orange seedling showing protuberances and bumps characteristic of infection with CIVV. These symptoms are typical and similar to those induced on mandarins or rough lemon leaves 

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Citrus_variegation_ilarvirus

Citrus variegation ilarvirus:

Symptoms on leaves of C. spectabilis infected with CIVV. 

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Citrus_vein_enation/woody_gall

Citrus vein enation/woody gall:

close-up of the trunk of a tree affected by woody gall.  

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Citrus_vein_enation/woody_gall

Citrus vein enation/woody gall:

Woody gall symptoms associated with the vein enation virus found on the trunk of a rough lemon in the field at the University of California, Riverside. 

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Citrus_viroid_symptoms

Citrus viroid symptoms in Gynura purpeae. The plant on the left is healthy, the center plant is infected with a mixture of citrus viroids but no citrus exocortis viroid, and the plant on the right is infected with citrus exocortis viroids plus the viroids present in the center plant.

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Citrus_viroids

Citrus viroids

Mild symptoms on leaves of 861-S-1 citron. These symptoms,expressed in varying degrees of severiity, are diagnostic for many of the citrus viroids

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Citrus_viroids

Citrus viroids

Temperature effect on 861-S-1 citron inoculated with a moderate-reacting mixture of citrus viroids. Plant on the left was grown at relatively cool temperatures; plant on the right was grown at warm temperatures. Note the complete absence of symptoms in the citron branch that was held at the cooler temperature

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CIVV

CIVV

Chlorotic lesions on primary leaves of cowpea infected with CIVV

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CIVV

CIVV

Necrotic local lesions on primary leaves of cowpea infected with CIVV (S.M. Garnsey)

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CIVV

CIVV

Psorosis-like symptoms in young leaves of a rough lemon seedling inoculated with CIVV

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CIVV

CIVV

Symptoms of CIVV on leaves of navel orange from a tree in the field (Spain)

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CIVV

CIVV

Symptoms on a citron seedling showing severe epinasty, chlorotic variegation and leaf distortion induced by inoculation with CIVV (California)

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CIVV

CIVV

Symptoms on leaves of C. spectabilis infected with CIVV (S.M. Garnsey)

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CIVV

CIVV

Symptoms on mature leaves of an inoculated Madame Vinous sweet orange seedling showing protuberances and bumps characteristic of infection with CIVV. These symptoms are typical and similar to those induced on mandarins or rough lemon leaves

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CIVV

CIVV

Symptoms on secondary growth leaves of red kidney bean infected with CIVV, showing bright vein chlorosis (S.M. Garnsey)

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Concave_gum_disease

Concave gum disease

Concavities associated with concave gum diseases in the trunk of a sweet orange tree in the field (Spain)

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Concave_gum_disease

Concave gum disease

Concentric gum rings in a cross-section of a branch. This is highly symptomatic for concave gum disease when present with trunk concavities and OLP (R. Vogel)

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Concave_gum_disease

Concave gum disease

Concentric gum rings in a cross-section of a small twig. This is also symptomatic for concave gum disease (R. Vogel)

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Concave_gum_virus

Concave gum virus

A narrow oak-leaf pattern developed about the midvein in a leaf of Valencia orange. Note the strong interveinal flecking, usually the first symptom observed in leaves on plants inoculated with concave gum virus

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Concave_gum_virus

Concave gum virus

Strong oak-leaf patterns in the leaves from a field tree of Valencia orange showing concavities during the spring flush of growth

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Cristacortis

Cristacortis

A typical deep pit in the trunk, with corresponding peg in the bark of a Navelina orange tree infected with cristacortis (Spain)

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Cristacortis

Cristacortis

Cristacortis pits showing in the outer bark of a tangelo tree (Corsica)

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Cristacortis

Cristacortis

Typical pitting symptom of cristacortis in the trunk of both scion and rootstock. Scion is Clementine mandarin and rootstock is sour orange (Sicily)

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Cristacortis

Cristacortis

When a section is cut from the bark, the typical pits and pegs are visible in the trunk and inner bark (R. Vogel)

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Cristacortis_and_concave_gum_disease

Cristacortis and concave gum disease

Cross-section of a branch showing both cristacortis and concave gum. The concentric gum rings are associated with concave gum i, and the pitting in the outer circumference indicates cristacortis

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Cristacortis_infection

Cristacortis infection

Cross-section of a branch showing the deep pits caused by cristacortis infection (R. Vogel)

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Cristacortis_infection

Cristacortis infection

Severe pitting induced in a tangelo seedling inoculated with cristacortis-infected budwood (Specimen from R. Vogel)

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Cristacortis_infection

Cristacortis infection

Typical oak-leaf pattern in a leaf from a Dweet tangor indicator seedling. This symptom is typically associated with the cristacortis disease

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CTLV

CTLV

Bud-union crease of satsuma mandarin on trifoliate rootstock induced by citrus tatterleaf virus (CTLV). Specimen at Kuchinotsu, Japan

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CTLV

CTLV

Local lesions in a leaf of red kidney bean mechanically inoculated with CTLV (S.M. Garnsey)

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CTLV

CTLV

Severe tatterleaf reaction induced by CTLV showing bud-union crease and fluting in the trunk of Troyer citrange rootstock with satsuma orange scion ( E.C. Calavan)

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CTLV

CTLV

Symptoms in secondary growth leaves of Chenopodium Quinoa showing well-distributed spotting, chlorosis and distortion induced by mechanical leaf-rub inoculation with CTLV

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CTLV

CTLV

Symptoms of necrotic local lesions in the primary leaves of cowpea induced by mechanical transmission with CTLV from citrus tissue

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CTLV

CTLV

Symptoms of tatterleaf in leaves of Citrus excelsa from a seedling inoculated with CTLV. The non-inoculated control leaf is on the left. Note the tattered, irregular-edged leaves giving the disease its name

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CTLV

CTLV

Symptoms of tatterleaf in leaves of Rusk citrange inoculated with CTLV. Note deformed leaves with spots and blotches

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CTV_isolate

CTV isolate

A mild pit in the peeled stem of a Mexican lime seedling induced by the mild-reacting T-519 CTV isolate

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CVV-2

CVV-2

Symptoms of mild isolate CVV-2 on leaves of citron. Symptoms on lemon are quite similar (S.M. Garnsey)

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Diaphorina_citri

Diaphorina citri

Diaphorina citri feeding on a young shoot and leaves of a citrus tree. Note the angular position taken by the insect when feeding (Pakistan) (L.C. Cochran)

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Diaphorina_citri

Diaphorina citri

Drawing of adults and instars of Diaphorina citri and Trioza erytreae (Source: Catling, 1970)

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Drill

Drill

Cordless electric drill making a small hole in trunk

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Elsinoe_fawcettii

Elsinoe fawcettii:

Sweet orange scab, caused by Elsinoe australis, on sweet orange in Uruguay.  

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Female_Mexican_fruit_fly

Female Mexican fruit fly can deposit large numbers of eggs:

up to 40 eggs at a time, 100 or more a day, and about 2,000 over her life span. 

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Graduated_burette

Graduated burette

Graduated burette hanging from an inside limb

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Grapefruit_infected_

Grapefruit infected with green mold.

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greasy_spot,_Mycosphaerella

greasy spot, Mycosphaerella citri

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Greening_infection

Greening infection

A characteristic greening-affected branch showing leaves with chlorosis, mottle, and yellow midribs and veins (South Africa)

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Greening_infection

Greening infection

A typical greening-affected mandarin tree in the field (New Territories, Hong Kong)

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Greening_infection

Greening infection

Close-up of a leaf from a greening-affected tree showing vein yellowing and mottle (South Africa)

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Greening_infection

Greening infection

Emerging, stunted yellow shoots showing severe chlorosis, typical of greening infection. Yellow shoot or huang-longbing is the name given to this disease in mainland China (Taiwan Province)

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Greening_infection

Greening infection

Gracilicute-like bacteria found in cells of a greening-affected citrus leaf. Note trilayered bacterial wall (China) (Phoeo: Ke-Chung)

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Greening_infection

Greening infection

Typical greening of fruit. Two normal Valencia oranges surrounded by greening-affected fruit (South Africa). Note the stylar and greening and smaller fruit

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Guignardia_citricarpa

Guignardia citricarpa:

Hard spot lesions on citrus fruit in Brazil due to Guignardia citricarpa or citrus black spot. Pycnidia may be present in the center of the lesions. 

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Gum_pocket

Gum pocket:

Sweet orange tree on Poncirus trifoliate rootstock which is infected with gum pocket. The trees are stunted and nonproductive.

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Gumming

Gumming

The appearance of symptoms of gum in the Parson's Special mandarin occurs only at the cut-back joint area, but no symptoms show in the stem above or below the area surrounding the joint

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Gumming

Gumming

The first mild gumming symptom usually seen in an exploratory cut into the bud-union area

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Gumming_and_Cachexia

Gumming and Cachexia

A window in the trunk of a field tree of Ellendale mandarin showing severe symptoms of gumming on the bark and trunk typical of severe cachexia. Note the areas of gum in the cut-back section (Australia)

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Gummy_bark_symptoms

Gummy bark symptoms

A section of bark taken from a gummy bark-infected navel orange near Tarsus, Turkey, showing gum pockets in the bark, and the appearance of these same gum spots (c) when the bark is sliced tangentially

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Gummy_bark_symptoms

Gummy bark symptoms

Gummy bark symptoms on Jaffa orange in Syria (R. Vogel)

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Gummy_bark_symptoms

Gummy bark symptoms

Gummy bark symptoms in bark of navel orange near Tarsus, Turkey

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Hand_drill

Hand drill

Drilling into the tree trunk with a hand drill. The plastic tube shown entering the tree trunk is attached to the graduated cylinder in (a). It is filled with water, and water uptake is measured from the graduated cylinder

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Impietratura_infection

Impietratura infection

Circular, puffed, darker green or lighter coloured spots on the rind of a navel orange (Spain). This symptom is indicative of possible impietratura infection

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Impietratura_infection

Impietratura infection

Gum showing in the albedo when the rind is sliced somewhat deeper

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Impietratura_infection

Impietratura infection

Impietratura-induced gumming in albedo of a sectioned young grapefruit (Spain)

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Impietratura_infection

Impietratura infection

Impietrature-induced spotting and gumming in the rind and albedo of Navalina oranges; note the typical green spotting on coloured fruit (Spain)

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Impietratura_infection

Impietratura infection

Typical leaf flecking and oak-leaf patterns associated with impietratura disease. Leaves will show this pattern on field trees in the spring flush under cool conditions. Also, this symptom on index plants is used as an indication of the presence or absence of the virus after thermotherapy or shoot-tip grafting

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Impietratura_infection

Impietratura infection

When the rind is sliced with a knife, gum is seen in the rind directly beneath the discoloured spots of Figure 84

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Injection_procedure

Injection procedure

Injection procedure showing stopwatch and pressure being applied to the plunger of the syringe

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Inverse_pitting_on_orange

Inverse pitting on orange

A section of bark cut through the bud-union of a sweet orange on sour orange rootstock showing inverse pitting in the bark of the sour orange. Note the small, closely spaced pits in the inner bark. The sour orange trunk would show corresponding small pegs

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Mandarin,_Citrus_reticulata

Mandarin, Citrus reticulata

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Mandarin

Mandarin

Symptom reaction on Parson's Special mandarin after the bark is completely peeled -- Mild

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Mandarin

Mandarin

Symptom reaction on Parson's Special mandarin after the bark is completely peeled -- Very severe

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Mandarin_scion

Mandarin scion

Growth of a Parson's Special mandarin scion as a single shoot or leader. Note careful staking and tying

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Mandarin_scion_buds

Mandarin scion buds

Bending the rough lemon seedling just above the scion bud aids in the forcing of the Parson's Special mandarin scion bud

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Mexican_fruit_flies_laying_eggs

Mexican fruit flies laying eggs in 'grapefruit' before a test of the reduced-oxygen treatment.

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Necrosis

Necrosis

Necrosis of the upper portions of the leaves of a systemically infected sesame plant (Japan) (Photo: M. Miyakawa)

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Planococcus_citri,_adult

Planococcus citri, adult

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Pomelo,_Citrus_grandis

Pomelo, Citrus grandis

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Psorosis

Psorosis

Psorosis shock symptoms in inoculated seedlings of Madame Vinous sweet orange showing the wilt-like drooping of the new shoot. The young leaves will dry up and drop off

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Psorosis

Psorosis

Psorosis shock symptoms in inoculated young seedlings of Pineapple sweet orange. The plant on the left is completely shocked. Shock remnants will remain on the plant and do not drop off

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Psorosis

Psorosis

Severe scaly bark lesions of psorosis on a nucellar sweet orange tree in Concordia, Argentina

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Psorosis-A

Psorosis-A

Scaly bark symptoms of psorosis-A on the trunk of a sweet orange in California

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Psorosis-A

Psorosis-A

Staining of interior wood of a branch of sweet orange infected with psorosis-A. This symptom is diagnostic for psorosis-A when found on trees showing bark lesions as in (a)

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Psorosis-A

Psorosis-A

The effect of temperature on symptom expression, showing shock symptoms of psorosis-A inoculated sweet orange seedlings grown under relatively cool temperatures of 24 degrees 27 degrees C maximum day (left) compared with no symptoms on plants grown under relatively warm temperatures of 32-38 degrees C maximum day (right) (California)

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Psorosis-A

Psorosis-A

Young leaf symptoms in Dweet tangor. A non-inoculated control leaf is on the right

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Psorosis-A

Psorosis-A

Young leaf symptoms in Pineapple sweet orange. Mild psorosis-A symptoms in leaves of Pineapple sweet orange with non-inoculated control leaf on the right

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Psorosis-B

Psorosis-B

Lesion bark blisters of psorosis-B on a twig and thorn of sweet orange (above) with the non-inoculated control below

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Psorosis-B

Psorosis-B

Local lesions on leaves of Chenopodium quinoa induced by mechanical inoculation from ringspot or psorosis-B-infected citrus tissue (control leaves on right)

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Psorosis-B

Psorosis-B

Psorosis-B-induced, blister-like lesions on the underside of a sweet orange leaf. Similar lesions may be found on leaves of field trees infected with ringspot

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Ringspot

Ringspot

Mature ringspot-type leaf symptoms in mature leaves of Valencia orange (L.J. Klotz)

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Ringspot

Ringspot

Mature ringspot-type leaf symptoms in mature leaves of rough lemon

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Ringspot

Ringspot

Symptoms of ringspot on fruit of Clementine mandarin in Spain showing green spotting of fruit. Impietratura may be present

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Ringspot_psorosis

Ringspot psorosis

Leaf symptoms induced by ringspot psorosis inoculated to seedlings of Marsh grapefruit (California)

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Ringspot_Psorosis

Ringspot psorosis

Symptoms of ringspot psorosis on leaves and fruit of Navelina orange in Greece showing indented sunken areas on fruit

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SDV

SDV

Graft-inoculated satsuma seedlings inoculated with SDV. Non-inoculated control plant is on the left. Note the smaller-sized plants and spoon-shaped leaves. Photo taken by M. Miyakawa eight weeks after inoculation (Japan)

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SDV

SDV

Necrotic local lesions on inoculated cotyledons of a sesame plant inoculated by sap containing SDV (Japan) (M. Miyakawa)

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Seeding_yellows

Seeding yellows

A comparison of sour orange and Eureka lemon for their reaction to seven severe seeding-yellows isolates in experiments carried out over a five-year period. Note the similarity of reaction of sour orange and Eureka lemon to all seven isolates. Since sour orange seedlings are highly nucellar and uniform, and uniform nucellar seedlings of lemon are difficult to obtain, the sour orange is the preferred indicator

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Seedling_yellows

Seedling yellows

Close-up of seedling-yellows reaction in a sour orange seedling showing smaller pointed leaves and yellows reaction. Control plant on left

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Seedling_yellows

Seedling yellows

The time in weeks after inoculation for the first symptoms of seedling yellows to appear in grapefruit, sour orange and Eureka lemon. Graphs are based on seven severe seedling-yellows isolates inoculated into 1200 seedlings and recorded over a five-year period

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Seedling_yellows

Seedling yellows

Vein-corking symptoms on leaves of Mexican lime seedlings inoculated with a very severe seedling-yellows tristeza isolate

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Seedling_yellows

Seedling-yellows

Reaction in two Duncan grapefruit seedlings with a non-inoculated control in the centre. Note the severe stunting in the two inoculated seedlings

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Seedling_yellows

Seedling-yellows

Reaction in two standard sour orange seedlings with a non-inoculated control in the center. Note the stunting and yellows of the two inoculated seedlings

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Spiroplasma_citri

Spiroplasma citri:

A stubborn-infected Madame Vinous seedling on the right and a control plant on the left. Note the extreme stunting and chlorosis induced by stubborn infection.  

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Spiroplasma_citri

Spiroplasma citri:

A stubborn-infected young sweet orange tree in the nursery row (left) showing the small leaves and shorter internodes symptomatic for the disease in warm areas. Compare with the normal nursery tree on the right (California). 

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Spiroplasma_citri

Spiroplasma citri:

Chlorotic mosaic-like mottle in leaves from a stubborn-infected sweet orange tree. These are typical of leaves from stubborn or greening-affected trees.  

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Spiroplasma_citri

Spiroplasma citri:

S. citri. The causal organism of stubborn disease as seen in the dark-field microscope. Note the spiral-helical nature of the organism. Motility can been seen in the dark-field microscope.  

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Stainless-steel_insert

Stainless-steel insert

A stainless-steel insert, which is hammered into the tree and is used as the connecting bridge between the plastic (or rubber) tube and the hole in the trunk

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Stem_pitting_by_tristeza

Stem pitting by tristeza

Stem pitting in the peeled stem of sour orange. Normally the sour orange, sweet orange and rought lemon are resistant to stem pitting by many isolates of tristeza. However, this illustrates that there are tristeza isolates

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Stem_pitting_by_tristeza

Stem pitting by tristeza

Stem pitting in the peeled stem of sweet orange. Normally the sour orange, sweet orange and rought lemon are resistant to stem pitting by many isolates of tristeza. However, this illustrates that there are tristeza isolates

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Stem_pitting_by_tristeza

Stem pitting by tristeza

Stem pitting in the peeled stem of rough lemon. Normally the sour orange, sweet orange and rought lemon are resistant to stem pitting by many isolates of tristeza. However, this illustrates that there are tristeza isolates

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Stubborn_disease

Stubborn disease

A seedling with two side grafts showing a single young shoot to be trained as a single leader. The side graft technique is very effective in transmitting stubborn disease

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Stubborn_disease

Stubborn disease

A stubborn-infected young sweet orange tree in the nursery row (left) showing the small leaves and shorter internodes symptomatic for the disease in warm areas. Compare with the normal nursery tree on the right (California)

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Stubborn_disease

Stubborn disease

A stubborn-infected Madame Vinous seedling on the right and a control plant on the left. Note the extreme stunting and chlorosis induced by stubborn infection

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Stubborn_disease

Stubborn disease

Characteristic symptoms associated with infection by S. citri in leaves from a Madame Vinous sweet orange seedling showing pointed tips and translucent chlorotic spotting at the leaf margins and near the tips. These symptoms developed in a greenhouse under warm temperatures and will persist in mature leaves. The control non-inoculated leaf is on the left

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Stubborn_disease

Stubborn disease

Chlorotic mosaic-like mottle in leaves from a stubborn-infected sweet orange tree. These are typical of leaves from stubborn or greening-affected trees.

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Stubborn_disease

Stubborn disease

S. citri the casual organism of stubborn disease as seen in the dark-field microscope. Note the spiral-helical nature of the organism. Motility can be seen in the dark-field microscope (Calavan)

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Stubborn_disease

Stubborn disease

Seed abortion in a Valencia orange in California. The presence of small dark purple-coloured seed (right) is symptomatic for stubborn disease. Such seeds are excellent for culturing of S. citri. Normal seed from a normal fruit is on the left

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Stubborn_disease

Stubborn disease

The characteristically stunted and compressed appearance of a stubborn-infected navel orange tree. A non-infected normal tree of the same age is on the left (California)

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Stubborn_disease

Stubborn disease

The first symptoms of stubborn in a young shoot of an inoculated Madame Vinous sweet orange seedling. Note the slightly semi-wilted appearance of the young shoot and leaves

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Stubborn_disease

Stubborn disease

The stylar-end greening effect on fruit from a stubborn-infected navel orange tree in California. This symptom, induced by the presence of Spiroplasma citri, is indistinguishable from symptoms of fruit on greeninng-infected trees caused by Asian or South African greening (Figure 15)

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Stubborn_disease

Stubborn disease

Three stubborn-infected Madame Vinous plants on the left compared with three control plants on the right. Note the smaller leaves and compressed growth in the infected plants. Plants were inoculated by side grafting and held in a warm greenhouse

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Tatterleaf_effects

Tatterleaf effects

Breakage and separation of a tatterleaf-infected satsuma scion from its trifoliate rootstock. Specimen at Kuchinotsu, Japan

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Tatterleaf_virus

Tatterleaf virus:

Chlorotic lesions and leaf distortion on rusk citrange leaves infected with tatterleaf virus, the healthy leaves are on the right.

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Temperature_effect_on_symptoms

Temperature effects on symptoms

The effect of temperature on symptom expression, showing variation in leaf symptoms due to the effect of the above temperature regimes. The leaf on the left is from a plant grown under the cool temperature and the leaf on the right is from a plant grown under the warm temperature regime. Both plants were inoculated with the same inoculum

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Tip_browning

Tip browning (control on left)

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Trioza_erytreae

Trioza erytreae

Abundant greening organisms in the haemolymph of Trioza erytreae (J. Moll)

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Trioza_erytreae

Trioza_erytreae

Characteristic bumps on the underside of sweet orange leaves caused by the feeding of Trioza erytreae (South Africa)

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Tristeza

Tristeza

Stem pitting in the peeled stem of grapefruit. Normally the sour orange, sweet orange and rought lemon are resistant to stem pitting by many isolates of tristeza. However, this illustrates that there are tristeza isolates

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Tristeza

Tristeza

Vein-clearing symptoms in the leaf of a Mexican lime seedling (right) as viewed from the back of the leaf into direct sunlight. Control on the left

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Tristeza_isolate

Tristeza isolate

Mild vein-clearing flecks induced in a leaf of Mexican lime by a mild-reacting tristeza isolate

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Tristeza_isolates

Tristeza isolates

The time in weeks after inoculation for the first vein-clearing symptoms to appear in leaves of Mexican lime seedlings. Graphs are based on eight tristeza isolates inoculated into 355 seedlings recorded over a seven-year period. Most isolates induced vein clearing within eight weeks

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Tristeza_pitting

Tristeza pitting

Severe pitting in the peeled stems of Mexican lime seedlings. Most tristeza isolates will induce this type of pitting

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Tristeza_virus

Tristeza virus

Cupping on leaves of Mexican limes inoculated with tristeza virus. Note also vein clearing

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Tristeza_virus

Tristeza virus

Symptoms due to tristeza virus, viewed on the underside of a leaf of sweet orange by reflected light. Symptoms are the dark-gree-to-black broken lines in the leaf veins. These are the same areas that show up as translucent when viewed from the underside of the leaf in transmitted direct sunlight

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Tylenchulus_semipenetrans_female

Tylenchulus semipenetrans female swollen with eggs on root of citrus

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Tylenchulus_semipenetrans_female

Tylenchulus semipenetrans female swollen with eggs on root of citrus

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Unaspis_citri_on_lime_stems

Unaspis citri on lime stems

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Vein-enation_virus

Vein-enation virus

Vein enations on the underside of leaves of a Mexican lime seedling which had been graft-inoculated with vein-enation virus. A non-inoculated leaf is on the bottom

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Vein-enation_virus

Vein-enation virus

Vein enations on the underside of leaves of a sour orange seedling which had been graft-inoculated with the vein-enation virus

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Vein-enation_virus

Vein-enation virus

Woody galls in an older seedling of rough lemon. This seedling has been puncture-inoculated when small by Dr J.M. Wallace using needles

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Vein-enation_virus

Vein-enation virus

Woody-gall symptoms associated with the vein-enation virus found on the trunk of a rough lemon in the field at the University of California, Riverside

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Viral_effects

Viral effects

A branch from an infected field tree of satsuma mandarin showing typical spoon-or boat-shaped leaves (Japan)

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Viral_effects

Viral effects

A satsuma dwarf virus-infected tree in the field (right) showing typical stunting and dwarfing (Japan)

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Viral_effects

Viral effects

Symptoms on leaves from a satsuma seedling induced by graft-inoculation with buds from an infected tree in the field. Typical spoon- or boat-shaped leaves with occasional crinkle are seen (Japan)

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Xanthomonas_axonopodis_pv._citr

Xanthomonas axonopodis pv. citri on citrus leaf, Citrus sinensis

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Xylella_fastidiosa

Xylella fastidiosa:

A high magnification of a Xylella fastidiosa bacterium in the xylem vessel of a CVC infected tree. Note the triple layer membrane and ridged nature of the cell wall. 

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Xylella_fastidiosa

Xylella fastidiosa:

A higher magnification of a thin section across a xylem vessel from a tree infected with CVC showing the Xylella fastidiosa bacterium. 

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Xylella_fastidiosa

Xylella fastidiosa:

An example of the raised gummy lesions which form on the underside of the leaves (bottom leaf) as well as the chlorosis and necrotic areas on the upper surface of the leaves (upper leaves). 

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Xylella_fastidiosa

Xylella fastidiosa:

Fruit from CVC-infected trees are small, contain less juice, ripen earlier, and have a hard rind. The few large fruit on the top of this box are from a healthy tree, the rest of the fruit are from a CVC infected tree. 

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Xylella_fastidiosa

Xylella fastidiosa:

In parts of Argentina, a similar disease is called picoseta. This is the leaf symptoms on a sweet orange tree from Misiones, Argentina. 

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Xylella_fastidiosa

Xylella fastidiosa:

Often one sector of a tree will show the symptoms first. Zinc deficiency-like chlorosis is commonly the first symptom of CVC to show on a sector, followed by reduced fruit size.  

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Xylella_fastidiosa

Xylella fastidiosa:

The leaf symptoms of CVC begin with the interveinal chlorosis followed by the appearance of necrotic spots with a gummy raised lesion directly below on the underside of the leaf. It is not uncommon for young leaves to be asymptomatic. 

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Xylella_fastidiosa

Xylella fastidiosa:

The Xylella fastidiosa bacterium which causes CVC often reaches high concentrations in xylem vessels. 

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Xylella_fastidiosa

Xylella fastidiosa:

This slide illustrates the nature of the interveinal chlorosis on the leaves from CVC infected trees. 

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