Citrus Fruits:Key

KEY TO CITRUS PESTS AND NUTRITIONAL DISORDERS

Seed

Seed disorders are limited to disorders while in the ground and not to potential disorders inherent in the seed.

No Distinct Discoloration

Damping-off

Poor germination of seedlings, over-all or in patches, due to decay of sprouted seed before emergence of infection after emergence

Seedling

YELLOW

Albinism

Germination normal, but seedlings partially or completely deficient in chlorophyll

Fertilizer burn; Phytophthora-induced root rot; Chemical injury; Water injury

Seedlings stunted, chlorotic, or necrotic; all or part of the root system dead

Fumigation-induced stunting; Mineral deficiencies

Germination normal, but seedlings remain small; leaves sometimes chlorotic or with marginal necrosis; roots remain alive

No Distinct Discoloration

Damping-off

Poor germination of seedlings, over-all or in patches, due to decay of sprouted seed before emergence of infection after emergence

Melanose; Lime anthracnose; Alternaria-induced diseases; Wind injury; Chemical injury

Distortion of emerging shoots and leaves, with extensive or localized necrosis

Scab

Distortion of shoots and leaves, with raised pustules, but little or no necrosis

Scab; Melanose; Alternaria-induced diseases; Canker; Lime anthracnose

Lesions or small eruptions appearing before new shoots have fully expanded or hardened

Scab; Wind injury; Aphid injury; Thrips injury; Psyllid injury; Broad mite injury

Distortion of emerging shoots or leaves, but little or not necrosis

Root

BROWN

Copper toxicity; Sting nematode

Feeder roots few, dark brown, and stubby

DARK

Copper toxicity; Sting nematode

Feeder roots few, dark brown, and stubby

No Distinct Discoloration

Dry root rot

Dead bark evident above the ground at the base of the trunk or in crown roots; wood rot progressing upward from roots into the trunk, but usually not into the scion

Fertilizer burn; Phytophthora-induced foot rot; Herbicide injury; Termite injury

Dead bark evident above the ground at the base of the trunk or in crown roots; dead or missing bark around the trunk, particularly at the soil level

Fertilizer burn; Phytophthora-induced root rot; Chemical injury; Water injury

Seedlings stunted, chlorotic, or necrotic; all or part of the root system dead

Mushroom root rot

Sudden wilt and loss of bark on crown roots or at the base of the trunk, with fan-shaped mycelial growth between the wood and the bark; trees often affected in groups, with the disease spreading outward from an infection focus

Mushroom root rot; Rosellinia root rot

Dead bark evident above the ground at the base of the trunk or in crown roots; rotting of bark, with fan-shaped mycelial sheets between the bark and the wood

Phytophthora-induced foot rot

Dead bark evident above the ground at the base of the trunk or in crown roots; rotting of bark, but not extending far into roots; rotting of bark, but not extending far into roots; gummy ooze if the infection is still active

Phytophthora-induced foot rot; Mushroom root rot

Rotting of bark at the base of the trunk, with gummy ooze if the lesion is still active

Phytophthora-induced gummosis and foot rot

Rotting of bark on the trunk, which may 1) extend into crown roots, 2) form discrete lesions or girdles not extending to the ground; 3) occur only above the bud union, or 4) extend across the bud union

Phytophthora-induced root rot; Water injury

Rotting of feeder roots

Tristeza

Decline or death of trees on sour orange rootstock

Tristeza

Stunting or decline of trees on sour orange rootstock; honeycombing may occur on the inner side of the bark below the bud union

Water injury

Dead bark evident above the ground at the base of the trunk or in crown roots; sloughing of bark or roots, with a disagreeable smell

Water injury

Sudden wilt and dropping of leaves, particularly affecting trees in low areas of orchards; disagreeable odor may be detected when the root zone is dug; sloughing of bark, even on large roots

Water injury; Phytophthora-induced foot rot

Much root rot, but no injury evident in aboveground bark

Crown

BROWN

Tristeza (quick-decline effect)

Sudden wilt and death of trees on sour orange rootstock; leaves dry up on the tree before falling; yellow-brown zone often present at the bud union

YELLOW

Tristeza (quick-decline effect)

Sudden wilt and death of trees on sour orange rootstock; leaves dry up on the tree before falling; yellow-brown zone often present at the bud union

No Distinct Discoloration

Blast; Botrytis blight; Alternaria-induced diseases; Melanose; Phytophthora-induced shoot and leaf blight; Lime anthracnose; Freeze injury

Rapid collapse and shriveling of emerging shoots

Blight

Irreversible wilting and rolling of foliage and twig dieback; zinc deficiency symptoms may occur on leaves; trunk sprouts may develop

Dry root rot

Dead bark evident above the ground at the base of the trunk or in crown roots; wood rot progressing upward from roots into the trunk, but usually not into the scion

Fertilizer burn; Herbicide Injury; Termite injury

Dead or missing bark on the trunk of young trees, usually near the soil level

Fertilizer burn; Phytophthora-induced foot rot; Herbicide injury; Termite injury

Dead bark evident above the ground at the base of the trunk or in crown roots; dead or missing bark around the trunk, particularly at the soil level

Freeze injury; Sunscald

Dead bark on the trunk, down to the bud union or to the ground

Inherited abnormalities; Some virus diseases

Overgrowths of bark at the bud union or pitting or gum impregnation of the bark or wood at the bud union

Mushroom root rot

Sudden wilt and loss of bark on crown roots or at the base of the trunk, with fan-shaped mycelial growth between the wood and the bark; trees often affected in groups, with the disease spreading outward from an infection focus

Mushroom root rot; Rosellinia root rot

Dead bark evident above the ground at the base of the trunk or in crown roots; rotting of bark, with fan-shaped mycelial sheets between the bark and the wood

Phytophthora-induced foot rot

Dead bark evident above the ground at the base of the trunk or in crown roots; rotting of bark, but not extending far into roots; gummy ooze if the infection is still active

Phytophthora-induced foot rot; Mushroom root rot

Rotting of bark at the base of the trunk, with gummy ooze if the lesion is still active

Phytophthora-induced gummosis and foot rot

Rotting of bark on the trunk, which may 1) extend into crown roots, 2) form discrete lesions or girdles not extending to the ground; 3) occur only above the bud union, or 4) extend across the bud union

Tristeza

Stunting or decline of trees on sour orange rootstock, resulting from early infection of trees or from the propagation of trees from infected budwood

Tristeza

Stunting or decline of trees on sour orange rootstock; honeycombing may occur on the inner side of the bark below the bud union

Tristeza

Stunting or decline of trees on sour orange rootstock, resulting from early infection of trees or from the propagation of trees from infected budwood

Water injury

Dead bark evident above the ground at the base of the trunk or in crown roots; sloughing of bark or roots, with a disagreeable smell

Stem

GREEN

Leprosis

Yellow spots on green stems followed by scaling of bark or gum impregnation after the bark forms

ORANGE

Pink disease and thread blight

Dieback of limbs, with pink or orange fungal growth on the bark

PINK

Mal secco

Sudden wilt of leaves and dieback of twigs and limbs, sometimes affecting entire trees; pink discoloration in the wood; currently known only in the Mediterranean area, and mostly on lemons

Pink disease and thread blight

Dieback of limbs, with pink or orange fungal growth on the bark

YELLOW

Leprosis

Yellow spots on green stems followed by scaling of bark or gum impregnation after the bark forms

No Distinct Discoloration

Algal disease; Felt

Localized or extensive felty growths on stems, appearing only after the new flush has fully expanded

Blast; Botrytis blight; Alternaria-induced diseases; Melanose; Phytophthora-induced shoot and leaf blight; Lime anthracnose; Freeze injury

Rapid collapse and shriveling of emerging shoots

Blight

Irreversible wilting and rolling of foliage and twig dieback; zinc deficiency symptoms may occur on leaves; trunk sprouts may develop

Bud-union incompatibility; Some virus diseases

Overgrowth at the bud union of some scion-rootstock combinations

Cachexia

Discoloration and gum impregnation of bark, in distinct pockets, with rounded pegs growing from the bark into the wood, on sweet lime, alemow, and some tangelos

Copper deficiency

Gumming of young stems, with little necrosis initially, but with dieback commonly occurring later

Dry root rot

Dead bark evident above the ground at the base of the trunk or in crown roots; wood rot progressing upward from roots into the trunk, but usually not into the scion

Exocortis

Splitting and scaling of bark on the rootstock portion of the trunk of trees on trifoliate orange or some trifoliate orange hybrid rootstocks or on Rangpur lime rootstock

Exocortis

Scaling of bark of susceptible rootstocks (trifoliate orange, some trifoliate orange hybrids, and Rangpur lime)

Fertilizer burn; Herbicide Injury; Termite injury

Dead or missing bark on the trunk of young trees, usually near the soil level

Fertilizer burn; Phytophthora-induced foot rot; Herbicide injury; Termite injury

Dead bark evident above the ground at the base of the trunk or in crown roots; dead or missing bark around the trunk, particularly at the soil level

Freeze injury

Dead bark or bark shedding, particularly in crotches, on the upper side of horizontal or inclined limbs, or on exposed branches

Freeze injury; Sunscald

Dead bark on the trunk, down to the bud union or to the ground

Greening

Trees stunted; leaves small, upright, and mottled, often with interveinal chlorosis and dieback; fruit small and poorly colored

Inherited abnormalities; Some virus diseases

Overgrowths of bark at the bud union or pitting or gum impregnation of the bark or wood at the bud union

Leprosis

Scaling of bark on twigs and limbs

Lightning injury

Sudden death of a single tree or a small group of trees; nearby trees may have dead shoot terminals

Lightning injury

Dead bark in a narrow strip running down the trunk, sometimes extending laterally at the base of the trunk to girdle the tree

Melanose; Lime anthracnose; Alternaria-induced diseases; Wind injury; Chemical injury

Distortion of emerging shoots and leaves, with extensive or localized necrosis

Mushroom root rot

Sudden wilt and loss of bark on crown roots or at the base of the trunk, with fan-shaped mycelial growth between the wood and the bark; trees often affected in groups, with the disease spreading outward from an infection focus

Mushroom root rot; Rosellinia root rot

Dead bark evident above the ground at the base of the trunk or in crown roots; rotting of bark, with fan-shaped mycelial sheets between the bark and the wood

Phytophthora-induced foot rot

Dead bark evident above the ground at the base of the trunk or in crown roots; rotting of bark, but not extending far into roots; gummy ooze if the infection is still active

Phytophthora-induced foot rot; Mushroom root rot

Rotting of bark at the base of the trunk, with gummy ooze if the lesion is still active

Phytophthora-induced gummosis and foot rot

Rotting of bark on the trunk, which may 1) extend into crown roots, 2) form discrete lesions or girdles not extending to the ground; 3) occur only above the bud union, or 4) extend across the bud union

Psorosis; Ringspot

Localized or extensive scaling of bark on the trunk and major limbs; limbs may die

Psorosis; Ringspot

Scaling of bark of the trunk and major limbs

Rio Grande gummosis

Localized scaling of the trunk following cracking of the bark and gumming

RioGrande gummosis; Phytophthora-induced gummosis

Localized vertical cracks in bark on the trunk above the bud union with release of gum

Robinson dieback

Dieback of Robinson tangerine, affectivng one or more limbs, with gumming at the border between living and dead bark

Robinson dieback

Dieback of some twigs and limbs on otherwise vigorous Robinson tangerine trees, often with gumming at the border between dead and living bark

Satsuma dwarf

Satsuma mandarin leaves small and boat- or spoon-shaped and trees stunted

Scab; Melanose; Alternaria-induced diseases; Canker; Lime anthracnose

Lesions or small eruptions appearing before new shoots have fully expanded or hardened

Scab; Wind injury; Aphid injury; Thrips injury; Psyllid injury; Broad mite injury

Distortion of emerging shoots or leaves, but little or not necrosis

Shell bark

Scaling of bark of the trunk of lemon trees

Sphaeropsis knot; Inherited abnormalities

Multiple bud break producing witches'-broom symptoms

Sphaeropsis knot; Inherited abnormalities; Vein enation virus (woody gall)

Galls on the trunk or limbs

Spreading decline (Burrowing nematode)

Tree decline spreading progressively from a center of infestation

Stem pitting (tristeza)

Vertical depressions on grapefruit trunks

Sunscald

Separation of bark from the wood of the trunk and limbs, particularly on the side exposed to direct sun, following transplanting, sudden defoliation, or severe pruning

Tangerine and Murcott collapse

Dieback or decline of all or a part of the canopy of Murcott and some tangerine cultivars

Tristeza (stem-pitting strains)

Pitting of twigs of declining sweet orange or grapefruit trees, exposed when bark is peeled

Wood rot; Freeze injury; Sunscald; Chemical injury

Dead wood in the trunk or major limbs following loss of bark or direct injury to the wood

Wood rot; Sunscald; Freeze injury

Extensive areas of dead bark on trunks

Leaf

BLACK

Cercospora leaf and fruit spot

Reddish brown to black spots of varying size on the rind, with a sunken center

Greasy spot; Greasy-spot-like diseases

Orange, brown, or black, irregular or circular areas of widely varying size on leaves, with epidermis raised, particularly on the lower surface of the leaf

Sooty mold

Black removable deposit on leaves

BROWN

Cercospora leaf and fruit spot

Reddish brown to black spots of varying size on the rind, with a sunken center

Fertilizer burn; Herbicide injury

Sunken brown lesions confined to low-hanging fruit

Greasy spot; Greasy-spot-like diseases

Orange, brown, or black, irregular or circular areas of widely varying size on leaves, with epidermis raised, particularly on the lower surface of the leaf

Measles

Chlorotic spots, few to numerous, their underside gray to brown and slightly raised

DARK

Areolate leaf spot

Light-colored necrotic areas with widely spaced, darker concentric rings

GRAY

Algal disease

Yellowish green, gray, or red patches on leaves

Measles

Chlorotic spots, few to numerous, their underside gray to brown and slightly raised

Spider mite injury

Lusterless, grayish leaves with pale stippling on the upper surface

GREEN

Algal disease

Yellowish green, gray, or red patches on leaves

Magnesium deficiency

Extensive chlorosis of older leaves, with a wedge of green tissue remaining along the midrib

Phytophthora-induced foot rot; Freeze injury; Mechanical injury; Chemical injury; Ant and termite injury

Leaves yellowish green and midrib and major veins pale yellow, as a result of girdling

LIGHT

Areolate leaf spot

Light-colored necrotic areas with widely spaced, darker concentric rings

Phytophthora-induced foot rot; Freeze injury; Mechanical injury; Chemical injury; Ant and termite injury

Leaves yellowish green and midrib and major veins pale yellow, as a result of girdling

Spider mite injury

Lusterless, grayish leaves with pale stippling on the upper surface

ORANGE

Greasy spot; Greasy-spot-like diseases

Orange, brown, or black, irregular or circular areas of widely varying size on leaves, with epidermis raised, particularly on the lower surface of the leaf

RED

Algal disease

Yellowish green, gray, or red patches on leaves

Aschersonia growing on whitefly nymphs

Red or yellow fungal structures on leaves, removable by rubbing

Cercospora leaf and fruit spot

Reddish brown to black spots of varying size on the rind, with a sunken center

WHITE

Powdery mildew

White patches on leaves

YELLOW

Algal disease

Yellowish green, gray, or red patches on leaves

Aschersonia growing on whitefly nymphs

Red or yellow fungal structures on leaves, removable by rubbing

Biuret toxicity; Boron toxicity; Perchlorate toxicity; Salt injury; Fertilizer burn; Some nutritional deficiencies

Interveinal chlorosis, mostly at the tip or margins of the leaf blade, sometimes followed by necrosis in these areas

Blight; Greening; Stubborn; Some nutritional deficiencies

Interveinal chlorosis, generally distributed over the whole leaf blade

Canker

Raised pustules with yellow halos on leaves, but little or no leaf distortion

Canker; Other bacterial canker diseases; Cercospora leaf and fruit spot; Alternaria-induced diseases; Greasy spot; Melanose; Leprosis; Chemical injury

Discrete or coalescent, irregular or circular, necrotic spots or pustules with a pronounced yellow halo, which may disappear with age

Greening

Trees stunted; leaves small, upright, and mottled, often with interveinal chlorosis and dieback; fruit small and poorly colored

Greening; Stubborn

Chlorotic mottle with yellowing of the midrib and major veins

Herbicide injury

Clearing or yellowing of veins on leaves

Magnesium deficiency

Extensive chlorosis of older leaves, with a wedge of green tissue remaining along the midrib

Mesophyll collapse

Irregular chlorotic areas between the midrib and the leaf margin, later becoming necrotic

Mineral deficiencies and toxicities

Interveinal chlorotic patterns on young leaves

Mineral deficiencies; Drought; Nematodes (heavy infestations)

Leaves small and chlorotic

Molybdenum deficiency; Some mite injuries; Leprosis

Large chlorotic spots on leaves

Phytophthora-induced foot rot; Freeze injury; Mechanical injury; Chemical injury; Ant and termite injury

Leaves yellowish green and midrib and major veins pale yellow, as a result of girdling

Psorosis

Temporary chlorotic flecking pattern on both sides of the midrib, producing a mirror-image effect, on growth flushes that emerge under cool conditions

Ringspot

Yellowish ring spots, blotches, or etchings on young or old leaves, necrosis of young shoots

No Distinct Discoloration

Alternaria-induced diseases; Chemical injury; Snail injury

Shot holes in leaves

Blight

Irreversible wilting and rolling of foliage and twig dieback; zinc deficiency symptoms may occur on leaves; trunk sprouts may develop

Blight; Greening; Stubborn; Tristeza

Leaves small and upright

Cercospora leaf and fruit spot; Black spot; Greasy spot; Greasy-spot-like diseases

Leaf spots appearing only after the leaves have fully expanded

Chimera or mutation; Infectious variegation

Leaves abnormally shaped or variegated

Fumigation-induced stunting; Mineral deficiencies

Germination normal, but seedlings remain small; leaves sometimes chlorotic or with marginal necrosis; roots remain alive

Infectious variegation

Crinkling and mottling of leaves

Mal secco

Sudden wilt of leaves and dieback of twigs and limbs, sometimes affecting entire trees; pink discoloration in the wood; currently known only in the Mediterranean area, and mostly on lemons

Melanose; Lime anthracnose; Alternaria-induced diseases; Wind injury; Chemical injury

Distortion of emerging shoots and leaves, with extensive or localized necrosis

Nematodes; Phytophthora-induced root rot; Mineral deficiencies and toxicities; Drought

Leaves and fruit small

Satsuma dwarf

Satsuma mandarin leaves small and boat- or spoon-shaped and trees stunted

Scab

Distortion of shoots and leaves, with raised pustules, but little or no necrosis

Scab; Wind injury; Aphid injury; Thrips injury; Psyllid injury; Broad mite injury

Distortion of emerging shoots or leaves, but little or not necrosis

Stubborn

Leaves small and upright; fruit small and malformed

Tangerine and Murcott collapse

Dieback or decline of all or a part of the canopy of Murcott and some tangerine cultivars

Tristeza

Localized veinclearing of Key and Tahiti lime leaves

Tristeza (quick-decline effect)

Sudden wilt and death of trees on sour orange rootstock; leaves dry up on the tree before falling; yellow-brown zone often present at the bud union

Water injury

Sudden wilt and dropping of leaves, particularly affecting trees in low areas of orchards; disagreeable odor may be detected when the root zone is dug; sloughing of bark, even on large roots

Fruit

BLACK

Alternaria rot

Brown to black rot, sometimes evident on the fruit surface and sometimes occurring only internally; premature coloring of infected fruit

Anthracnose

Firm, initially brown to black, sunken spot or rot with pink spore masses, which later appear black

Aspergillus rot

Soft rots that soon form conspicuous black spore masses

Black pit

Brown or black lesions of varying size on lemons

Cercospora leaf and fruit spot

Reddish brown to black spots of varying size on the rind, with a sunken center

Chemical injury

Brown or black discoloration on the side of the fruit exposed to the sun

Chemical injury

Gray, brown, or black half-circular or irregular markings or thin lines on fruit

Chemical injury

Superficial gray, brown or black blotches on fruit

Greasy spot rind blotch; Chemical injury; Citrus rust mite injury

Superficial brown or black discoloration of the rind, consisting of discrete or coalescent groups of dead cells between oil glands; associated with the death of guard cells and nearby epidermal or substomatal cells

Pleospora rot

Very dark brown to almost black rot, both outside and inside the fruit

Rumple

Slightly depressed chlorotic areas on lemons, later becoming greenish brown or black

Septoria spot

Small, depressed spots on the rind, sometimes numerous enough to coalesce and form extensive brown to black blotches

Sooty mold

Removable black mold growth on the rind

BLUE

Blue mold

Soft rots that soon form conspicuous blue spore masses

BROWN

Alternaria brown spot of mandarins

Deep indentations or pockmarks in the rind of susceptible mandarins and their hybrids

Alternaria brown spot of mandarins

Slowly enlarging, circular, firm brown lesions on some tangerines and their hybrids

Alternaria rot

Brown to black rot, sometimes evident on the fruit surface and sometimes occurring only internally; premature coloring of infected fruit

Alternaria-induced diseases

Necrotic spots; brown lesions with darker brown concentric rings on rough lemon, Rangpur lime, and some mandarins and mandarin hybrids

Anthracnose

Firm, initially brown to black, sunken spot or rot with pink spore masses, which later appear black

Black pit

Brown or black lesions of varying size on lemons

Black spot

Small, circular spots on the rind with a dark brown margin enclosing a gray, sunken center, which may contain pycnidia

Brown rot

Extensive necrotic areas and brown lesions on any part of the fruit, with a characteristic rotting odor

Brown rot

Light brown firm, leathery rot with a characteristic pungent, rancid odor, covered with white mycelium at high humidity

Cercospora leaf and fruit spot

Reddish brown to black spots of varying size on the rind, with a sunken center

Chemical injury

Brown or black discoloration on the side of the fruit exposed to the sun

Chemical injury

Gray, brown, or black half-circular or irregular markings or thin lines on fruit

Chemical injury

Superficial gray, brown or black blotches on fruit

Citrus rind mite injury

Smooth or only slightly roughened, gray, tan or russet brown areas on the rind

Copper deficiency

Brownish, gum-soaked areas on the rind

Cottony rot

Yellowish brown rot, covered with fluffy, cottony mycelium at high humidity

Diplodia stem-end rot; Dothiorella rot

Leathery, pliable, tan to brown rot, generally beginning at the stem end of the fruit; rapid decay between segments, producing fingerlike projections of discolored tissue

Fusarium rot

Leathery, beige, pink, or light to dark brown, sunken rot, developing slowly and producing surface mycelium at high humidity

Gray mold

Brown, leathery decay covered with gray-brown to olive spore masses

Greasy spot rind blotch; Chemical injury; Citrus rust mite injury

Superficial brown or black discoloration of the rind, consisting of discrete or coalescent groups of dead cells between oil glands; associated with the death of guard cells and nearby epidermal or substomatal cells

Impietratura; Boron deficiency

Brownish depressions or protuberances on the rind, with pockets of gum in the albedo

Leprosis

Rusty brown spots on the rind with sunken centers

Lime blotch

Sectorial, slightly sunken, olive brown bands extending from the stem end to the stylar end of Tahiti lime

Oleocellosis

Slightly sunken, brown tissue between oil glands

Phomopsis stem-end rot

Leathery, pliable, tan to brown rot, generally beginning at the stem end of the fruit; fingerlike projections of decay are not produced

Pleospora rot

Very dark brown to almost black rot, both outside and inside the fruit

Rumple

Slightly depressed chlorotic areas on lemons, later becoming greenish brown or black

Septoria spot

Small, depressed spots on the rind, sometimes numerous enough to coalesce and form extensive brown to black blotches

Stylar-end breakdown

Firm, brown necrosis at the stylar end of Tahiti lime

Trichoderma rot

Cocoa brown rot with a coconut-like odor, covered with coarse white mycelium and yellow-green to dark green spore masses

DARK

Alternaria-induced diseases

Necrotic spots; brown lesions with darker brown concentric rings on rough lemon, Rangpur lime, and some mandarins and mandarin hybrids

Black spot

Small, circular spots on the rind with a dark brown margin enclosing a gray, sunken center, which may contain pycnidia

Fusarium rot

Leathery, beige, pink, or light to dark brown, sunken rot, developing slowly and producing surface mycelium at high humidity

Pleospora rot

Very dark brown to almost black rot, both outside and inside the fruit

Sooty blotch and flyspeck

Surface blemish caused by dark-colored fungi that adhere tightly to the cuticle and cannot be removed by washing

Sour rot

Water-soaked, easily punctured, light to dark yellow, slightly raised rot, which disintegrates into a slimy, watery mass

Stem-end rind breakdown

Dry collapse and darkening of the rind at the stem end of the fruit

Trichoderma rot

Cocoa brown rot with a coconut-like odor, covered with coarse white mycelium and yellow-green to dark green spore masses

Zebra skin

Stripes of dark rind on mandarins, usually only on fruit picked early in the season

GRAY

Anthracnose

Scattered silvery gray, firm, nonsunken lesions covering much of the fruit of some mandarin cultivars

Black spot

Small, circular spots on the rind with a dark brown margin enclosing a gray, sunken center, which may contain pycnidia

Chemical injury

Gray, brown, or black half-circular or irregular markings or thin lines on fruit

Chemical injury

Superficial gray, brown or black blotches on fruit

Citrus rind mite injury

Smooth or only slightly roughened, gray, tan or russet brown areas on the rind

Gray mold

Brown, leathery decay covered with gray-brown to olive spore masses

GREEN

Green mold

Soft rots that soon form conspicuous olive green spore masses, even without high humidity

Ringspot

Circular green spots on fruit that do not color up, often appearing as rings

Rumple

Slightly depressed chlorotic areas on lemons, later becoming greenish brown or black

Trichoderma rot

Cocoa brown rot with a coconut-like odor, covered with coarse white mycelium and yellow-green to dark green spore masses

LIGHT

Fusarium rot

Leathery, beige, pink, or light to dark brown, sunken rot, developing slowly and producing surface mycelium at high humidity

Sour rot

Water-soaked, easily punctured, light to dark yellow, slightly raised rot, which disintegrates into a slimy, watery mass

OLIVE

Green mold

Soft rots that soon form conspicuous olive green spore masses, even without high humidity

Lime blotch

Sectorial, slightly sunken, olive brown bands extending from the stem end to the stylar end of Tahiti lime

PINK

Anthracnose

Firm, initially brown to black, sunken spot or rot with pink spore masses, which later appear black

Fusarium rot

Leathery, beige, pink, or light to dark brown, sunken rot, developing slowly and producing surface mycelium at high humidity

RED

Cercospora leaf and fruit spot

Reddish brown to black spots of varying size on the rind, with a sunken center

SILVER

Anthracnose

Scattered silvery gray, firm, nonsunken lesions covering much of the fruit of some mandarin cultivars

TAN

Citrus rind mite injury

Smooth or only slightly roughened, gray, tan or russet brown areas on the rind

Diplodia stem-end rot; Dothiorella rot

Leathery, pliable, tan to brown rot, generally beginning at the stem end of the fruit; rapid decay between segments, producing fingerlike projections of discolored tissue

Phomopsis stem-end rot

Leathery, pliable, tan to brown rot, generally beginning at the stem end of the fruit; fingerlike projections of decay are not produced

WHITE

Brown rot

Light brown firm, leathery rot with a characteristic pungent, rancid odor, covered with white mycelium at high humidity

Cottony rot

Yellowish brown rot, covered with fluffy, cottony mycelium at high humidity

Trichoderma rot

Cocoa brown rot with a coconut-like odor, covered with coarse white mycelium and yellow-green to dark green spore masses

YELLOW

Cottony rot

Yellowish brown rot, covered with fluffy, cottony mycelium at high humidity

Rumple

Slightly depressed chlorotic areas on lemons, later becoming greenish brown or black

Sour rot

Water-soaked, easily punctured, light to dark yellow, slightly raised rot, which disintegrates into a slimy, watery mass

Trichoderma rot

Cocoa brown rot with a coconut-like odor, covered with coarse white mycelium and yellow-green to dark green spore masses

No Distinct Discoloration

Algal disease

Circular, raised felty areas with irregular margins on the rind

Alternaria brown spot

Excessive fruit drop on susceptible mandarins and their hybrids

Anthracnose

Firm, initially brown to black, sunken spot or rot with pink spore masses, which later appear black

Botrytis blight; Wind injury; Scab

Irregular ridges or protuberances on the rind, little surface roughening, and no necrosis

Brown rot

Excessive fruit drop following usually long periods of rainfall and fruit wetting

Chilling injury

Sunken pits in the rind surface

Citrus bud mite injury

Fruit misshapen, with deep grooves

Citrus rust mite injury; Melanose; Anthracnose

Tearstain markings on the rind

Creasing

Grooves or furrow in an irregular pattern in the rind

Drought injury; Water injury; Freeze injury; Pest injury

Excessive fruit drop associated with various abiotic factors

Granulation

Shriveling of juice sacs, giving an appearance of crystallization, usually beginning at the stem end

Greening

Trees stunted; leaves small, upright, and mottled, often with interveinal chlorosis and dieback; fruit small and poorly colored

Greening; Stubborn

Fruit lopsided or acorn-shaped; coloring delayed

Hail injury; Fertilizer burn

Deep indentations in the rind, occurring on any cultivar

Nematodes; Phytophthora-induced root rot; Mineral deficiencies and toxicities; Drought

Leaves and fruit small

Postbloom fruit drop disease

Blossom blight or abscission of fruit soon after petal fall, with the button left firmly attached to the tree

Puffing

Separation of the peel from the pulp of mandarins

Scab; Melanose; Canker; Cancroid spot; Alternaria-induced diseases; Lime anthracnose

Discrete or coalescent, raised or fissured, corky pustules or markings on the rind

Stubborn

Leaves small and upright; fruit small and malformed