Apples Pears:Key

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KEY TO APPLE AND PEAR PESTS AND NUTRITIONAL DISORDERS


Contents

Rootstock

GREEN

Apple Stem Grooving

Long grooves develop on woody stems which can be seen after the bark is removed; sunken or flattened areas may develop without being noticed if the bark is not removed; swelling of the scion stem at the union with the rootstock often occurs and break easily revealing plates of necrotic xylem above the graft; scion may die while the rootstock remains healthy; leaves are small, pale green, and drop prematurely


ORANGEORANGE

Fire Blight

Decay is present in root, crown and/or lower trunk areas; advancing margin of infection sometimes orange in color, often a definite margin of infection; wood is slimy in appearance; decay may be restricted to interstem or rootstock only; milky droplets of ooze exuded on the surface on infected blossoms, cankers, fruits or shoots during moist conditions; infected tissues become scorched in appearance; blossom clusters wilt and collapse in late spring


YELLOW

Apple Chlorotic Leafspot

Usually only sensitive cultivars are susceptible to disease; chlorotic spots may develop on leaves; chlorotic rings and line patterns may develop on leaves causing them to drop prematurely; stunting; terminal dieback; inner bark necrosis; local bark necrosis at buds grafted; tree decline on sensitive rootstocks


No Distinct Discoloration

Apple Chlorotic Leafspot

Usually only sensitive cultivars are susceptible to disease; chlorotic spots may develop on leaves; chlorotic rings and line patterns may develop on leaves causing them to drop prematurely; stunting; terminal dieback; inner bark necrosis; local bark necrosis at buds grafted; tree decline on sensitive rootstocks

Apple Epinasty and Decline

Symptoms are manifest when grafted onto 'Spy 227' rootstock; rootstock and scion both die usually in the third year of growth; epinasty appears on the leaves; blades are curled downward; midsummer bark tissue becomes necrotic and growth ceases

Apple Epinasty and Decline

Symptoms are manifest when grafted onto 'Spy 227' rootstock; rootstock and scion both die usually in the third year of growth; epinasty appears on the leaves; blades are curled downward; midsummer bark tissue becomes necrotic and growth ceases

Apple Junction Necrotic Pitting

A characteristic line of pits encircles the junction of the rootstock and scion and is matched by necrotic phloem pegs; necrotic and stem pitting infections often occur together at the junction

Apple Junction Necrotic Pitting

A characteristic line of pits encircles the junction of the rootstock and scion and is matched by necrotic phloem pegs; necrotic and stem pitting infections often occur together at the junction

Apple Rubbery Wood

Abnormal flexibility of stems and branches in 1 to 3 year old trees; trees assume a drooping habit; internodes are shortened; annual growth is reduced, sometimes even stunted; rootstock productivity, tree vigor and yield may be reduced

Apple Stem Grooving

Long grooves develop on woody stems which can be seen after the bark is removed; sunken or flattened areas may develop without being noticed if the bark is not removed; swelling of the scion stem at the union with the rootstock often occurs and break easily revealing plates of necrotic xylem above the graft; scion may die while the rootstock remains healthy; leaves are small, pale green, and drop prematurely

Apple Stem Grooving

Long grooves develop on woody stems which can be seen after the bark is removed; sunken or flattened areas may develop without being noticed if the bark is not removed; swelling of the scion stem at the union with the rootstock often occurs and break easily revealing plates of necrotic xylem above the graft; scion may die while the rootstock remains healthy; leaves are small, pale green, and drop prematurely

Fire Blight

Decay is present in root, crown and/or lower trunk areas; advancing margin of infection sometimes orange in color, often a definite margin of infection; wood is slimy in appearance; decay may be restricted to interstem or rootstock only; milky droplets of ooze exuded on the surface on infected blossoms, cankers, fruits or shoots during moist conditions; infected tissues become scorched in appearance; blossom clusters wilt and collapse in late spring



Root

BROWN

Phytophthora Crown and Root Rot (Collar Rot)

Symptoms are difficult to detect; infected trees show a lack of vigor, minimal terminal growth, and discolored leaves; a reddish bronze to purple leaf discoloration if probably the first visible symptom; leaves may be light green in the summer turning reddish bronze in early autumn and yellow the following summer; fruit may be small and color prematurely; inner bark of the root system become light tan to dark brown; a chocolate brown discoloration and canker may be seen just above the soil line as the disease progresses


ORANGE

Fire Blight

Decay is present in root, crown and/or lower trunk areas; advancing margin of infection sometimes orange in color, often a definite margin of infection; wood is slimy in appearance; decay may be restricted to interstem or rootstock only; milky droplets of ooze exuded on the surface on infected blossoms, cankers, fruits or shoots during moist conditions; infected tissues become scorched in appearance; blossom clusters wilt and collapse in late spring


TAN

Phytophthora Crown and Root Rot (Collar Rot)

Symptoms are difficult to detect; infected trees show a lack of vigor, minimal terminal growth, and discolored leaves; a reddish bronze to purple leaf discoloration if probably the first visible symptom; leaves may be light green in the summer turning reddish bronze in early autumn and yellow the following summer; fruit may be small and color prematurely; inner bark of the root system become light tan to dark brown; a chocolate brown discoloration and canker may be seen just above the soil line as the disease progresses


WHITE

Armillaria Root Rot

Bark at crown and roots easily slough off exposing dense white to yellowish fungus growth with fan shaped distribution at cambium; black shoestring-like strands may be obvious on surface of bark and yellow-brown mushrooms may appear at the base of the tree in late summer or early fall


YELLOW

Armillaria Root Rot

Bark at crown and roots easily slough off exposing dense white to yellowish fungus growth with fan shaped distribution at cambium; black shoestring-like strands may be obvious on surface of bark and yellow-brown mushrooms may appear at the base of the tree in late summer or early fall


No Distinct Discoloration

Apple Epinasty and Decline

Symptoms are manifest when grafted onto 'Spy 227' rootstock; rootstock and scion both die usually in the third year of growth; epinasty appears on the leaves; blades are curled downward; midsummer bark tissue becomes necrotic and growth ceases

Apple Junction Necrotic Pitting

A characteristic line of pits encircles the junction of the rootstock and scion and is matched by necrotic phloem pegs; necrotic and stem pitting infections often occur together at the junction

Apple Proliferation

Elongated stipules and leaf rosettes develop on the terminal parts of shoots; root systems form compact, felt-like masses which causes stunting; flowers may be delayed and have phyllody; leaves emerge earlier but are irregularly serrated and small; summer leaves are often chlorotic; fall foliage becomes purplish red early in the fall; fruits are small, few, incompletely colored and poorly flavored

Apple Stem Grooving

Long grooves develop on woody stems which can be seen after the bark is removed; sunken or flattened areas may develop without being noticed if the bark is not removed; swelling of the scion stem at the union with the rootstock often occurs and break easily revealing plates of necrotic xylem above the graft; scion may die while the rootstock remains healthy; leaves are small, pale green, and drop prematurely

Apple Stem Pitting

Root systems weaken and decline causing dieback of the scion; sunken depressions and grooving develop on the stem and the limbs below the union, and longitudinal sutures appear on the bark; symptoms usually develop in the second year following inoculation; moderate pitting in the wood occurs during the second year becoming worse in subsequent years; fruits are small and malformed with depressions

Crown Gall

Small to large, warty-appearing growths at the crown or in roots

Nematode Damage

Fibrous roots lacking or showing witches broom; most common on light textured soils; general tree growth and vigor is reduced; foliage wilted or off-color with early reddening and defoliation in the fall

Rodent Damage

Bark missing at or below the soil line; gnawing marks sometimes visible in wood; callus formed in bark at margin of bare wood; fibrous roots lacking or showing witches broom

Wooley Apple Aphid

Main injury to young and mature trees is stunting due to the formation of root galls; if populations are high, honeydew and sooty mold will also be problems and aphids may enter the calyx end of the fruit



Crown

BROWN

Phytophthora Crown and Root Rot (Collar Rot)

Symptoms are difficult to detect; infected trees show a lack of vigor, minimal terminal growth, and discolored leaves; a reddish bronze to purple leaf discoloration if probably the first visible symptom; leaves may be light green in the summer turning reddish bronze in early autumn and yellow the following summer; fruit may be small and color prematurely; inner bark of the root system become light tan to dark brown; a chocolate brown discoloration and canker may be seen just above the soil line as the disease progresses


ORANGE

Fire Blight

Decay is present in root, crown and/or lower trunk areas; advancing margin of infection sometimes orange in color, often a definite margin of infection; wood is slimy in appearance; decay may be restricted to interstem or rootstock only; milky droplets of ooze exuded on the surface on infected blossoms, cankers, fruits or shoots during moist conditions; infected tissues become scorched in appearance; blossom clusters wilt and collapse in late spring


WHITE

Armillaria Root Rot

Bark at crown and roots easily slough off exposing dense white to yellowish fungus growth with fan shaped distribution at cambium; black shoestring-like strands may be obvious on surface of bark and yellow-brown mushrooms may appear at the base of the tree in late summer or early fall


YELLOW

Armillaria Root Rot

Bark at crown and roots easily slough off exposing dense white to yellowish fungus growth with fan shaped distribution at cambium; black shoestring-like strands may be obvious on surface of bark and yellow-brown mushrooms may appear at the base of the tree in late summer or early fall


No Distinct Discoloration

Crown Gall

Small to large, warty-appearing growths at the crown or in roots

Winter Freeze Injury

Funneled air space around base of the tree where water collected and froze in contact with the tree crown



Stem

RED/PURPLE/BRONZE

Phytophthora Crown and Root Rot (Collar Rot)

Symptoms are difficult to detect; infected trees show a lack of vigor, minimal terminal growth, and discolored leaves; a reddish bronze to purple leaf discoloration if probably the first visible symptom; leaves may be light green in the summer turning reddish bronze in early autumn and yellow the following summer; fruit may be small and color prematurely; inner bark of the root system become light tan to dark brown; a chocolate brown discoloration and canker may be seen just above the soil line as the disease progresses


BLACK

Apple Internal Bark Necrosis

Two to three year old limbs will have raised spots in the bark that may appear as dark areas or blackish necrotic spots under the bark; dieback of small limbs may occur

Apple Pustule Canker

Pustules form on the bark of 2 to 3 year old trees; tissues beneath the bark are black and necrotic; no gum formation develops; dark, dead tissues become brittle and peel; individual pockmark depressions or large cankers can form

Apple Union Necrosis and Decline

Small, greenish yellow leaves, short internodes, amply flowering and many small bright fruits are characteristic symptoms; bark turns reddish with protruding lenticles; lateral leaves and buds die off, terminal shoots are short and clustered; trunk above the graft may swell; removing the thick and spongy bark at the scion/stock union reveals a distinct necrotic line; more suckers than normal develop from below the graft union; distinct black sunken line at union below the bark; trees may break at the union

Armillaria Root Rot

Bark at crown and roots easily slough off exposing dense white to yellowish fungus growth with fan shaped distribution at cambium; black shoestring-like strands may be obvious on surface of bark and yellow-brown mushrooms may appear at the base of the tree in late summer or early fall

Black Rot

Leaf lesions are frog-eyed in appearance, necrotic and may contain small black spherical pycnidia; infected fruit has extensive soft decay and rows of pyncidia; black pyncidia may develop on canker surface initiated by a large pruning cut or winter injury


BROWN

Anthracnose

Small, circular, red or purple spots develop early on when fruit is moist and become elliptical, sunken, orange to brown areas in the bark as they grow; cracks develop between the diseased and healthy tissue causing a cream-colored acervuli to appear through cracks in the periderm; bark sloughs off older cankers exposing the wood beneath; most cankers are found on small twigs and branches

Apple Decline

Common in commercial cultivars; leaves may appear chlorotic; trees become stunted; bark becomes reddish brown; swelling and brown necrotic lines appear at or near the union; trees die after 4-5 years; small, deformed, premature fruit; foliage may be sparse and light green

Apple Powdery Mildew

Fungus infects apple leaves, blossoms and fruit; commonly whitish, feltlife patches of fungal mycelium develops on the lower leaf surface; lesions appear as chlorotic spots on the upper leaf surface and may spread leaving the leaf with a white, mealy coating; leaf curling may occur; terminals and internodes are often stunted and covered with white lesions; with age, lesions turn gray or brown; may cause a net-like pattern of russetting on the fruit; fungus may appear on the twigs of infected branches

European Canker

Reddish-brown lesions begin to appear on small branches just below leaf scars developing into cankers with concentric ridges that may cause dieback of shoots in the spring; calyx rot of fruits can occur in years when rain precedes harvest; may be confused with fire blight


CREAM

Anthracnose

Small, circular, red or purple spots develop early on when fruit is moist and become elliptical, sunken, orange to brown areas in the bark as they grow; cracks develop between the diseased and healthy tissue causing a cream-colored acervuli to appear through cracks in the periderm; bark sloughs off older cankers exposing the wood beneath; most cankers are found on small twigs and branches


GRAY

Apple Powdery Mildew

Fungus infects apple leaves, blossoms and fruit; commonly whitish, feltlife patches of fungal mycelium develops on the lower leaf surface; lesions appear as chlorotic spots on the upper leaf surface and may spread leaving the leaf with a white, mealy coating; leaf curling may occur; terminals and internodes are often stunted and covered with white lesions; with age, lesions turn gray or brown; may cause a net-like pattern of russetting on the fruit; fungus may appear on the twigs of infected branches


ORANGE

Anthracnose

Small, circular, red or purple spots develop early on when fruit is moist and become elliptical, sunken, orange to brown areas in the bark as they grow; cracks develop between the diseased and healthy tissue causing a cream-colored acervuli to appear through cracks in the periderm; bark sloughs off older cankers exposing the wood beneath; most cankers are found on small twigs and branches

Apple Blister Bark

No leaf or fruit symptoms are present; dry, paper thin, orange areas develop on the bark and slough off causing the underlying tissue to dry, peel, and crack; internal bark necrosis and twig dieback occurs on limbs that are 1 year old or older

Fire Blight

Decay is present in root, crown and/or lower trunk areas; advancing margin of infection sometimes orange in color, often a definite margin of infection; wood is slimy in appearance; decay may be restricted to interstem or rootstock only; milky droplets of ooze exuded on the surface on infected blossoms, cankers, fruits or shoots during moist conditions; infected tissues become scorched in appearance; blossom clusters wilt and collapse in late spring

Nectria Twig Blight

Wilting and death of new shoots appear in midsummer; pink to orange fungus sporulation is apparent near the previous seasons fruit scar or on older wood


PINK

Apple Dead Spur

Fruiting spurs in the tree's center die; weak spurs have smaller and fewer leaves and delayed leaf abscission in the fall; phloem may be pink; fruit has no diagnostic symptoms

Nectria Twig Blight

Wilting and death of new shoots appear in midsummer; pink to orange fungus sporulation is apparent near the previous seasons fruit scar or on older wood


PURPLE

Apple Leaf Fleck, Bark Blister, Fruit Russet and Distortion

Found only to occur in New Zealand; leaves develop pale green flecks with some puckering and distortion; fruits are distorted and have areas of light brown russet, occasionally forming rings; dark purple eruptions may merge and form extensive cankers on the bark


RED

Apple Decline

Common in commercial cultivars; leaves may appear chlorotic; trees become stunted; bark becomes reddish brown; swelling and brown necrotic lines appear at or near the union; trees die after 4-5 years; small, deformed, premature fruit; foliage may be sparse and light green

Apple Union Necrosis and Decline

Small, greenish yellow leaves, short internodes, amply flowering and many small bright fruits are characteristic symptoms; bark turns reddish with protruding lenticles; lateral leaves and buds die off, terminal shoots are short and clustered; trunk above the graft may swell; removing the thick and spongy bark at the scion/stock union reveals a distinct necrotic line; more suckers than normal develop from below the graft union; distinct black sunken line at union below the bark; trees may break at the union

European Canker

Reddish-brown lesions appear on small branches just below leaf scars developing into cankers with concentric ridges that may cause dieback of shoots in the spring; calyx rot of fruits can occur in years when rain precedes harvest; pruning wound infections are seen occasionally; may be confused with fire blight


WHITE

Apple Powdery Mildew

Fungus infects apple leaves, blossoms and fruit; commonly whitish, feltlife patches of fungal mycelium develops on the lower leaf surface; lesions appear as chlorotic spots on the upper leaf surface and may spread leaving the leaf with a white, mealy coating; leaf curling may occur; terminals and internodes are often stunted and covered with white lesions; with age, lesions turn gray or brown; may cause a net-like pattern of russetting on the fruit; fungus may appear on the twigs of infected branches


No Distinct Discoloration

Apple Chlorotic Leafspot

Usually only sensitive cultivars are susceptible to disease; chlorotic spots may develop on leaves; chlorotic rings and line patterns may develop on leaves causing them to drop prematurely; stunting; terminal dieback; inner bark necrosis; local bark necrosis at buds grafted; tree decline on sensitive rootstocks

Apple Epinasty and Decline

Symptoms are manifest when grafted onto 'Spy 227' rootstock; rootstock and scion both die usually in the third year of growth; epinasty appears on the leaves; blades are curled downward; midsummer bark tissue becomes necrotic and growth ceases

Apple Flat Limb

Sensitive cultivars may experience linear depressions or flattening of shoots or branches, usually on older wood; these depressions become deeper as the tree matures finally causing the bark to split open; affected limbs are less vigorous, easily broken and more susceptible to canker and frost damage

Apple Freckle Scurf

Small, elevated freckles appear on the bark, under which thin tissue layers are formed; these freckles crack open allowing the bark to scab and peel; no leaf or fruit symptoms

Apple Fruit Blotch

Leaf veins and adjacent tissue develop cream-colored spotting; petals may be deformed with flecks or rings of red or brown pigment; bark develops blistering on the trunk and basal regions of branches; fruits exhibit large red or brown spots, occasionally becoming rings 3-4 centimeters in diameter

Apple Horseshoe Wound

Horseshoe shaped wounds develop on the bark below or around the buds; trees are stunted; flowering is delayed and the number of flowers is reduced

Apple Junction Necrotic Pitting

A characteristic line of pits encircles the junction of the rootstock and scion and is matched by necrotic phloem pegs; necrotic and stem pitting infections often occur together at the junction

Apple Rosette

Growth of the trees in stunted; leaves form rosettes because of short internodes; leaves are small, brittle, curled upwards and deeply serrated; infected trees produce little or no fruit

Apple Rubbery Wood

Abnormal flexibility of stems and branches in 1 to 3 year old trees; trees assume a drooping habit; internodes are shortened; annual growth is reduced, sometimes even stunted; rootstock productivity, tree vigor and yield may be reduced

Apple Scaly Bark

Stem and woody parts of lateral shoots of young trees develop roughened and scaly bark, possibly with a slight swelling at the base of the tree; scaly bark usually occurs on the main stem and at the base of year-old lateral shoots; trees are often dwarfed; heavily distorted leaves with chlorotic spots often occur

Apple Scaly Bark

Evident only on Malus platycarpa species; stem and woody parts of lateral shoots of young trees becomes roughened and scaly; a slight swelling at the base of the tree may occur; scaly bark usually occurs on the main stem and one year old shoots; trees are stunted; leaves become heavily distorted with chlorotic spots

Apple Star Crack

Bark necrosis develops around the buds of one-year-old shoots; bark symptoms may be rough bark spots to open cankers; shoot tips often dieback; bud break can be premature or delayed and flowering can be abnormal; leaves often become chlorotic and cupped at the shoot tips in the fall; star-shaped cracks develop on the skin of the fruit; fruit is small and sometimes experience having slight depressions and rough skin

Apple Stem Grooving

Long grooves develop on woody stems which can be seen after the bark is removed; sunken or flattened areas may develop without being noticed if the bark is not removed; swelling of the scion stem at the union with the rootstock often occurs and break easily revealing plates of necrotic xylem above the graft; scion may die while the rootstock remains healthy; leaves are small, pale green, and drop prematurely

Apple Stem Pitting

Root systems weaken and decline causing dieback of the scion; sunken depressions and grooving develop on the stem and the limbs below the union, and longitudinal sutures appear on the bark; symptoms usually develop in the second year following inoculation; moderate pitting in the wood occurs during the second year becoming worse in subsequent years; fruits are small and malformed with depressions

Bacterial Blossom Blast

Fruit buds infected in early bloom stop growing, turn brown and papery, and may drop off; later infections affect flower petals and stems, and fruit cluster bases turn brown or black; infection usually does not move beyond the base of the fruit cluster, however, sometimes fruit spurs are killed; flower symptoms may closely resemble fire blight but there is no bacterial ooze present

Cribrate Weevil

Young trees may be stunted or killed by defoliation and bark feeding; insignificant damage usually occurs on mature trees; notching out of the edge of the leaf is characteristic giving the leaf a ragged appearance; with higher populations, the whole leaf except the veins as well as the bark on twigs may be consumed; young trees are particularly susceptible to defoliation, stunting, and tree loss; white larvae overwinter on the roots but do not seem to cause significant damage

Green Apple Aphid

Aphids infest succulent terminal growth and sometimes fruit; high populations on young trees may retard normal growth and result in irregular shoot growth; on bearing trees, heavy infestations of aphids may cover the fruit and foliage with honeydew on which a black, sooty mold develops; mold can hinder leaf function and lower fruit grade

Italian Pear Scale

Feeds directly on the wood of the tree affecting tree vigor and causing reduced fruit size; does not attack fruit; apple trees can withstand high populations before experiencing significant damage

Nectria Canker

Target-shaped perennial cankers on limbs and/or trunk

Perennial Canker

Most common symptom is the development of concentric rings of dead wood around a sunken center; the disease usually starts around a pruning wound or some other injury and the woolly apple aphid feeds at these wounds creating small wounds until a ring of dead tissue is present; winter injury of the tissue encourages the growth of the disease; the severity of the disease increases with excess succulent growth, such as high nitrogen fertilization or overirrigation, or factors that weaken the tree

Rodent Damage

Bark missing at or below the soil line; gnawing marks sometimes visible in wood; callus formed in bark at margin of bare wood; fibrous roots lacking or showing witches broom

San Jose Scale

Trees may be seriously damaged, resulting in reduced vigor, thin foliage, cracked or dying branches, and the eventual death of the tree; young trees may be killed before fruiting; infested fruit develop a reddish-purple ring surrounding each spot where a scale settles

Western Tussock Moth

A heavy infestation will destroy all spring growth; larvae take shallow bites out of newly set, young fruit; these injured areas eventually scab over and russet; infestations are spotty and may be isolated in certain areas of an orchard



Leaf

BLACK

Apple Scab

Scab first appears on the undersides of new leaves as olive green to black spots which become brown and velvety with time; leaves may turn yellow and drop prematurely if the petiole becomes infected; long periods of wetness encourage the disease and may attack the fruit any time in its development; maturing fruit may crack and/or be misshapen and warty in appearance; early infections may result in blighting of blossoms and dropping of young fruits

Black Rot

Leaf lesions are frog-eyed in appearance, necrotic and may contain small black spherical pycnidia; infected fruit has extensive soft decay and rows of pyncidia; black pyncidia may develop on canker surface initiated by a large pruning cut or winter injury


BRONZE

European Red Mite

Severe mite infestations can cause bronzing of leaves, and may lead to small, poorly colored fruit and reduced bloom the following year; damage is relatively less severe on wide leaf varieties

Phytophthora Crown and Root Rot (Collar Rot)

Symptoms are difficult to detect; infected trees show a lack of vigor, minimal terminal growth, and discolored leaves; a reddish bronze to purple leaf discoloration if probably the first visible symptom; leaves may be light green in the summer turning reddish bronze in early autumn and yellow the following summer; fruit may be small and color prematurely; inner bark of the root system become light tan to dark brown; a chocolate brown discoloration and canker may be seen just above the soil line as the disease progresses

Webspinning Spider Mites

Mites feed on leaves, removing cell contents and gradually giving leaves a finely stippled appearance; heavy infestations result in severe bronzing of foliage and premature defoliation; fruit on heavily infested trees fail to color and size properly and fruit production for the following year may be lowered


BROWN

Apple Scab

Scab first appears on the undersides of new leaves as olive green to black spots which become brown and velvety with time; leaves may turn yellow and drop prematurely if the petiole becomes infected; long periods of wetness encourage the disease and may attack the fruit any time in its development; maturing fruit may crack and/or be misshapen and warty in appearance; early infections may result in blighting of blossoms and dropping of young fruits


CREAM

Apple Fruit Blotch

Leaf veins and adjacent tissue develop cream-colored spotting; petals may be deformed with flecks or rings of red or brown pigment; bark develops blistering on the trunk and basal regions of branches; fruits exhibit large red or brown spots, occasionally becoming rings 3-4 centimeters in diameter

Apple Mosaic

Pale yellow to bright cream-colored areas develop on leaves in bands along the veins and may become chrome yellow or white as the disease progresses; necrotic areas may appear on severely infected leaves causing them to drop prematurely; growth and yield may be reduced in sensitive cultivars; fruit indicate no noticeable symptoms


GREEN

Apple Decline

Common in commercial cultivars; leaves may appear chlorotic; trees become stunted; bark becomes reddish brown; swelling and brown necrotic lines appear at or near the union; trees die after 4-5 years; small, deformed, premature fruit; foliage may be sparse and light green

Apple Leaf Fleck, Bark Blister, Fruit Russet and Distortion

Found only to occur in New Zealand; leaves develop pale green flecks with some puckering and distortion; fruits are distorted and have areas of light brown russet, occasionally forming rings; dark purple eruptions may merge and form extensive cankers on the bark

Apple Ring Russeting

Leaves exhibit light green vein flecking on scattered leaves during some seasons; rings and oak-leaf patterns may develop on leaves of some Delicious types; fruit shows russet ring during most seasons

Apple Scab

Scab first appears on the undersides of new leaves as olive green to black spots which become brown and velvety with time; leaves may turn yellow and drop prematurely if the petiole becomes infected; long periods of wetness encourage the disease and may attack the fruit any time in its development; maturing fruit may crack and/or be misshapen and warty in appearance; early infections may result in blighting of blossoms and dropping of young fruits

Apple Stem Grooving

Long grooves develop on woody stems which can be seen after the bark is removed; sunken or flattened areas may develop without being noticed if the bark is not removed; swelling of the scion stem at the union with the rootstock often occurs and break easily revealing plates of necrotic xylem above the graft; scion may die while the rootstock remains healthy; leaves are small, pale green, and drop prematurely


LIGHT

Leafminers

Damage is restricted to foliage; larvae feed on cells between upper and lower epidermal layers of the leaf leaving only the epidermal layers; upper side of the leaf takes on a light, spotted appearance; heavy infestations cause premature defoliation and leaf function is impaired and fruit may fail in size and color


PURPLE

Apple Proliferation

Elongated stipules and leaf rosettes develop on the terminal parts of shoots; root systems form compact, felt-like masses which causes stunting; flowers may be delayed and have phyllody; leaves emerge earlier but are irregularly serrated and small; summer leaves are often chlorotic; fall foliage becomes purplish red early in the fall; fruits are small, few, incompletely colored and poorly flavored

Phytophthora Crown and Root Rot (Collar Rot)

Symptoms are difficult to detect; infected trees show a lack of vigor, minimal terminal growth, and discolored leaves; a reddish bronze to purple leaf discoloration if probably the first visible symptom; leaves may be light green in the summer turning reddish bronze in early autumn and yellow the following summer; fruit may be small and color prematurely; inner bark of the root system become light tan to dark brown; a chocolate brown discoloration and canker may be seen just above the soil line as the disease progresses


RED

Apple Proliferation

Elongated stipules and leaf rosettes develop on the terminal parts of shoots; root systems form compact, felt-like masses which causes stunting; flowers may be delayed and have phyllody; leaves emerge earlier but are irregularly serrated and small; summer leaves are often chlorotic; fall foliage becomes purplish red early in the fall; fruits are small, few, incompletely colored and poorly flavored

Nematode Damage

Fibrous roots lacking or showing witches broom; most common on light textured soils; general tree growth and vigor is reduced; foliage wilted or off-color with early reddening and defoliation in the fall

Phytophthora Crown and Root Rot (Collar Rot)

Symptoms are difficult to detect; infected trees show a lack of vigor, minimal terminal growth, and discolored leaves; a reddish bronze to purple leaf discoloration if probably the first visible symptom; leaves may be light green in the summer turning reddish bronze in early autumn and yellow the following summer; fruit may be small and color prematurely; inner bark of the root system become light tan to dark brown; a chocolate brown discoloration and canker may be seen just above the soil line as the disease progresses


WHITE

Apple Mosaic

Pale yellow to bright cream-colored areas develop on leaves in bands along the veins and may become chrome yellow or white as the disease progresses; necrotic areas may appear on severely infected leaves causing them to drop prematurely; growth and yield may be reduced in sensitive cultivars; fruit indicate no noticeable symptoms

Apple Powdery Mildew

Fungus infects apple leaves, blossoms and fruit; commonly whitish, feltlife patches of fungal mycelium develops on the lower leaf surface; lesions appear as chlorotic spots on the upper leaf surface and may spread leaving the leaf with a white, mealy coating; leaf curling may occur; terminals and internodes are often stunted and covered with white lesions; with age, lesions turn gray or brown; may cause a net-like pattern of russetting on the fruit; fungus may appear on the twigs of infected branches

Leafhoppers

Leafhoppers feed by sucking on leaf tissue causing a white stippling on leaves; fruit may be reduced in size and buds may be weakened; excrement dropped by leafhoppers with appear as black specks on apples and are easily removed by washing; also produces honeydew which forms into sticky droplets around the calyx end after rainfall or overhead sprinkling and is not easily removed


YELLOW

Apple Brown Ringspot

Small yellow spots or chlorotic rings form on leaves between the veins sometimes forming longitudinal spots; fruits develop dark green spots which take on irregular shapes as the fruit matures; during and after harvest, brown ringspots are surrounded by green watery tissue; necrotic areas can develop on the fruit underneath blemished areas

Apple Bumpy Fruit

Small yellow spots develop on the leaves on the veins and adjacent tissue; fruits become malformed with depressions and bumps

Apple Chlorotic Leafspot

Usually only sensitive cultivars are susceptible to disease; chlorotic spots may develop on leaves; chlorotic rings and line patterns may develop on leaves causing them to drop prematurely; stunting; terminal dieback; inner bark necrosis; local bark necrosis at buds grafted; tree decline on sensitive rootstocks

Apple Decline

Common in commercial cultivars; leaves may appear chlorotic; trees become stunted; bark becomes reddish brown; swelling and brown necrotic lines appear at or near the union; trees die after 4-5 years; small, deformed, premature fruit; foliage may be sparse and light green

Apple Mosaic

Pale yellow to bright cream-colored areas develop on leaves in bands along the veins and may become chrome yellow or white as the disease progresses; necrotic areas may appear on severely infected leaves causing them to drop prematurely; growth and yield may be reduced in sensitive cultivars; fruit indicate no noticeable symptoms

Apple Powdery Mildew

Fungus infects apple leaves, blossoms and fruit; commonly whitish, feltlife patches of fungal mycelium develops on the lower leaf surface; lesions appear as chlorotic spots on the upper leaf surface and may spread leaving the leaf with a white, mealy coating; leaf curling may occur; terminals and internodes are often stunted and covered with white lesions; with age, lesions turn gray or brown; may cause a net-like pattern of russetting on the fruit; fungus may appear on the twigs of infected branches

Apple Proliferation

Elongated stipules and leaf rosettes develop on the terminal parts of shoots; root systems form compact, felt-like masses which causes stunting; flowers may be delayed and have phyllody; leaves emerge earlier but are irregularly serrated and small; summer leaves are often chlorotic; fall foliage becomes purplish red early in the fall; fruits are small, few, incompletely colored and poorly flavored

Apple Ring and Line Pattern

Leaves exhibit yellow rings, lines and oak leaf patterns

Apple Russet Wart

Russetted wart-like protuberances with superficial necrotic spots develop on the fruit surface; some varieties may have fruit that is malformed or develop necrotic russet rings on the fruit surface; leaves are small with chlorotic rings, spots or necrotic spots; symptoms appear on fruiting spurs and leaves of shoots

Apple Scab

Scab first appears on the undersides of new leaves as olive green to black spots which become brown and velvety with time; leaves may turn yellow and drop prematurely if the petiole becomes infected; long periods of wetness encourage the disease and may attack the fruit any time in its development; maturing fruit may crack and/or be misshapen and warty in appearance; early infections may result in blighting of blossoms and dropping of young fruits

Apple Scaly Bark

Evident only on Malus platycarpa species; stem and woody parts of lateral shoots of young trees becomes roughened and scaly; a slight swelling at the base of the tree may occur; scaly bark usually occurs on the main stem and one year old shoots; trees are stunted; leaves become heavily distorted with chlorotic spots

Apple Star Crack

Bark necrosis develops around the buds of one-year-old shoots; bark symptoms may be rough bark spots to open cankers; shoot tips often dieback; bud break can be premature or delayed and flowering can be abnormal; leaves often become chlorotic and cupped at the shoot tips in the fall; star-shaped cracks develop on the skin of the fruit; fruit is small and sometimes experience having slight depressions and rough skin

Apple Union Necrosis and Decline

Small, greenish yellow leaves, short internodes, amply flowering and many small bright fruits are characteristic symptoms; bark turns reddish with protruding lenticles; lateral leaves and buds die off, terminal shoots are short and clustered; trunk above the graft may swell; removing the thick and spongy bark at the scion/stock union reveals a distinct necrotic line; more suckers than normal develop from below the graft union; distinct black sunken line at union below the bark; trees may break at the union

Phytophthora Crown and Root Rot (Collar Rot)

Symptoms are difficult to detect; infected trees show a lack of vigor, minimal terminal growth, and discolored leaves; a reddish bronze to purple leaf discoloration if probably the first visible symptom; leaves may be light green in the summer turning reddish bronze in early autumn and yellow the following summer; fruit may be small and color prematurely; inner bark of the root system become light tan to dark brown; a chocolate brown discoloration and canker may be seen just above the soil line as the disease progresses


No Distinct Discoloration

Apple Dead Spur

Fruiting spurs in the tree's center die; weak spurs have smaller and fewer leaves and delayed leaf abscission in the fall; phloem may be pink; fruit has no diagnostic symptoms

Apple Depression

Leaves of infected 'McIntosh' trees suffer severe mosaic; irregular depressions develop on the fruit leaving the surface flat; these flat surfaces will take on a red color earlier than the fruit

Apple Epinasty and Decline

Symptoms are manifest when grafted onto 'Spy 227' rootstock; rootstock and scion both die usually in the third year of growth; epinasty appears on the leaves; blades are curled downward; midsummer bark tissue becomes necrotic and growth ceases

Apple Flat Apple

Fruit becomes compressed from both the stalk and calyx side and appear flattened; fruit are smaller and tend to flatter; leaves on some infected varieties roll upward from the midrib

Apple Little Leaf

Leaves are small, mottled and deformed; leaf buds open later than those of healthy branches, or may not open at all; shortened internodes

Apple Narrow Leaf

Leaves are small and narrow, even strap like; whole branches will be affected; symptoms are less distinctive with age, the most noticeable symptoms being evident in the second year after infection

Apple Necrosis

Infected trees exhibit necrotic spots that are several millimeters in diameter on new leaves during the spring and summer; occurs only in Japan

Apple Pandemis

Overwintered larvae feed on blooms and on the surface of young fruit causing them to drop or resulting in scarring and distortion; when apple pandemis tie leaves to fruit they cause shallow feeding scars; sometimes they feed for only a short time and produce several small circular holes in fruit

Apple Rosette

Growth of the trees in stunted; leaves form rosettes because of short internodes; leaves are small, brittle, curled upwards and deeply serrated; infected trees produce little or no fruit

Apple Rough Skin

Rough, dark brown corky areas on the fruit give it a scabby appearance; corky patches may appear as spots or partial rings; star-shaped cracks may form on the affected areas under cooler conditions; the first spur leaf will be puckered and flecked

Apple Russet Ring

Type A: Produces foliage that exhibits puckering and flecking, often in rings and lines; fruit develops slightly sunken rings, white or green in color, that become yellowish brown as the fruit ripens; Type B: No leaf symptoms but fruit shows russet areas usually in rings or incomplete circles

Cribrate Weevil

Young trees may be stunted or killed by defoliation and bark feeding; insignificant damage usually occurs on mature trees; notching out of the edge of the leaf is characteristic giving the leaf a ragged appearance; with higher populations, the whole leaf except the veins as well as the bark on twigs may be consumed; young trees are particularly susceptible to defoliation, stunting, and tree loss; white larvae overwinter on the roots but do not seem to cause significant damage

Fruittree Leafroller

Feeds principally on leaves but also on blossoms, flower buds and fruits during bloom; tiny larvae work their way into opening leaf buds to feed; once the tree has leafed out, larvae tie up leaves and live within leafrolls feeding on leaves or fruit; larvae damage fruit in much the same way as green fruitworms, resulting in shallow cavities in the fruit; damaged fruits that remain on the tree develop deep bronze-colored scars with roughened, netlike surfaces

Green Apple Aphid

Aphids infest succulent terminal growth and sometimes fruit; high populations on young trees may retard normal growth and result in irregular shoot growth; on bearing trees, heavy infestations of aphids may cover the fruit and foliage with honeydew on which a black, sooty mold develops; mold can hinder leaf function and lower fruit grade

Green Fruitworms

Young fruitworms larvae feed on leaves; fruit feeding usually begins about petal fall and continues until larvae have completed their development; these fruit are misshapen and have large, roughened, russeted cavities

Omnivorous Leafroller

Larvae often web leaves into rolled protective shelters while feeding; they feed on leaves and on the surface of fruit, sometimes webbing one or more leaves to the fruit for protection; they chew shallow holes or grooves in the fruit surface, often near the stem end; larvae feed where fruit are touching so entire clusters can be damaged

Orange Tortrix

Most damage caused by larvae is feeding on the surface of fruit where they leave shallow, irregular scars; they usually feed within a fruit cluster; occasionally they tie a leaf to the fruit's surface and feed under it

Rosy Apple Aphid

Aphids cluster on leaves of fruit spurs and growing shoots where they cause severe leaf curling; fruits on heavily infested fruit spurs fail to properly develop and become misshapen

San Jose Scale

Trees may be seriously damaged, resulting in reduced vigor, thin foliage, cracked or dying branches, and the eventual death of the tree; young trees may be killed before fruiting; infested fruit develop a reddish-purple ring surrounding each spot where a scale settles



Flower

RED

Apple Fruit Blotch

Leaf veins and adjacent tissue develop cream-colored spotting; petals may be deformed with flecks or rings of red or brown pigment; bark develops blistering on the trunk and basal regions of branches; fruits exhibit large red or brown spots, occasionally becoming rings 3-4 centimeters in diameter


BROWN

Apple Fruit Blotch

Leaf veins and adjacent tissue develop cream-colored spotting; petals may be deformed with flecks or rings of red or brown pigment; bark develops blistering on the trunk and basal regions of branches; fruits exhibit large red or brown spots, occasionally becoming rings 3-4 centimeters in diameter

Bacterial Blossom Blast

Fruit buds infected in early bloom stop growing, turn brown and papery, and may drop off; later infections affect flower petals and stems, and fruit cluster bases turn brown or black; infection usually does not move beyond the base of the fruit cluster, however, sometimes fruit spurs are killed; flower symptoms may closely resemble fire blight but there is no bacterial ooze present


WHITE

Apple Powdery Mildew

Fungus infects apple leaves, blossoms and fruit; commonly whitish, feltlife patches of fungal mycelium develops on the lower leaf surface; lesions appear as chlorotic spots on the upper leaf surface and may spread leaving the leaf with a white, mealy coating; leaf curling may occur; terminals and internodes are often stunted and covered with white lesions; with age, lesions turn gray or brown; may cause a net-like pattern of russetting on the fruit; fungus may appear on the twigs of infected branches


No Distinct Discoloration

Apple Horseshoe Wound

Horseshoe shaped wounds develop on the bark below or around the buds; trees are stunted; flowering is delayed and the number of flowers is reduced

Apple Pandemis

Overwintered larvae feed on blooms and on the surface of young fruit causing them to drop or resulting in scarring and distortion; when apple pandemis tie leaves to fruit they cause shallow feeding scars; sometimes they feed for only a short time and produce several small circular holes in fruit

Apple Proliferation

Elongated stipules and leaf rosettes develop on the terminal parts of shoots; root systems form compact, felt-like masses which causes stunting; flowers may be delayed and have phyllody; leaves emerge earlier but are irregularly serrated and small; summer leaves are often chlorotic; fall foliage becomes purplish red early in the fall; fruits are small, few, incompletely colored and poorly flavored

Apple Ringspot

Small, light-colored, reddish-brown areas appear under the bloom and only after fruit is 3 centimeters in diameter; as fruit ripens, the surface of the spots becomes rough and rusty and their margins intersected with small cracks; at harvest, dark, thin bands form around the rusty areas; incomplete rings form on the skin

Apple Scab

Scab first appears on the undersides of new leaves as olive green to black spots which become brown and velvety with time; leaves may turn yellow and drop prematurely if the petiole becomes infected; long periods of wetness encourage the disease and may attack the fruit any time in its development; maturing fruit may crack and/or be misshapen and warty in appearance; early infections may result in blighting of blossoms and dropping of young fruits

Apple Star Crack

Bark necrosis develops around the buds of one-year-old shoots; bark symptoms may be rough bark spots to open cankers; shoot tips often dieback; bud break can be premature or delayed and flowering can be abnormal; leaves often become chlorotic and cupped at the shoot tips in the fall; star-shaped cracks develop on the skin of the fruit; fruit is small and sometimes experience having slight depressions and rough skin

European Red Mite

Severe mite infestations can cause bronzing of leaves, and may lead to small, poorly colored fruit and reduced bloom the following year; damage is relatively less severe on wide leaf varieties

Fire Blight

Decay is present in root, crown and/or lower trunk areas; advancing margin of infection sometimes orange in color, often a definite margin of infection; wood is slimy in appearance; decay may be restricted to interstem or rootstock only; milky droplets of ooze exuded on the surface on infected blossoms, cankers, fruits or shoots during moist conditions; infected tissues become scorched in appearance; blossom clusters wilt and collapse in late spring

Lygus Bugs

Lygus bugs may feed on developing flower buds early in spring, causing the buds to exude gum and shrivel up with a heavy infestation; the most serious damage is by feeding directly on fruit; midseason feeding results in round pits, and late season feeding causes irregularly-shaped depressions that are similar to stink bug damage

Obliquebanded Leafroller

Larvae feed on flower parts and on fruit early in the season, causing deep depressions that eventually become rough and russeted by harvest; damage from the summer generation is usually more serious and results in superficial skin tunnels or small holes near the stem portions of the fruit



Fruit

No Distinct Discoloration

Apple Stem Pitting

Root systems weaken and decline causing dieback of the scion; sunken depressions and grooving develop on the stem and the limbs below the union, and longitudinal sutures appear on the bark; symptoms usually develop in the second year following inoculation; moderate pitting in the wood occurs during the second year becoming worse in subsequent years; fruits are small and malformed with depressions


BLACK

Bacterial Blossom Blast

Fruit buds infected in early bloom stop growing, turn brown and papery, and may drop off; later infections affect flower petals and stems, and fruit cluster bases turn brown or black; infection usually does not move beyond the base of the fruit cluster, however, sometimes fruit spurs are killed; flower symptoms may closely resemble fire blight but there is no bacterial ooze present


Blister Spot

Lesions 1-5 mm in diameter occurring only on the fruit, purplish black in color associate with stomata

Fly Speck

Superficial fungus growth, showing black speckled pattern on fruit, mostly apparent near harvest

Green Apple Aphid

Aphids infest succulent terminal growth and sometimes fruit; high populations on young trees may retard normal growth and result in irregular shoot growth; on bearing trees, heavy infestations of aphids may cover the fruit and foliage with honeydew on which a black, sooty mold develops; mold can hinder leaf function and lower fruit grade

Leafhoppers

Leafhoppers feed by sucking on leaf tissue causing a white stippling on leaves; fruit may be reduced in size and buds may be weakened; excrement dropped by leafhoppers with appear as black specks on apples and are easily removed by washing; also produces honeydew which forms into sticky droplets around the calyx end after rainfall or overhead sprinkling and is not easily removed

Moldy Core

Infection initiating at the open calyx and then extending inward to cause a black fungus core rot; fruits ripen early and the decay of fruit is only obvious when fruit are cut in half; an important disease on varieties with an open calyx

Sooty Blotch

Black, blotchy, sooty fungus growth on the surface of fruit, most apparent near harvest

White Rot

Fruit symptoms are usually seen 4 to 6 weeks before harvest as small, slightly sunken brown spots that may be surrounded by a red halo; as the decay area expands, the core becomes rotten and eventually the entire fruits rot; the flesh is soft and watery under warm conditions; red-skinned fruit may bleach during the decay process and become light brown; infections on the wood develop around the lenticels as small spots or blisters that become watery and eventually black pyncidia appear


BRONZE

Fruittree Leafroller

Feeds principally on leaves but also on blossoms, flower buds and fruits during bloom; tiny larvae work their way into opening leaf buds to feed; once the tree has leafed out, larvae tie up leaves and live within leafrolls feeding on leaves or fruit; larvae damage fruit in much the same way as green fruitworms, resulting in shallow cavities in the fruit; damaged fruits that remain on the tree develop deep bronze-colored scars with roughened, netlike surfaces


BROWN

Apple Brown Ringspot

Small yellow spots or chlorotic rings form on leaves between the veins sometimes forming longitudinal spots; fruits develop dark green spots which take on irregular shapes as the fruit matures; during and after harvest, brown ringspots are surrounded by green watery tissue; necrotic areas can develop on the fruit underneath blemished areas

Apple Fruit Blotch

Leaf veins and adjacent tissue develop cream-colored spotting; petals may be deformed with flecks or rings of red or brown pigment; bark develops blistering on the trunk and basal regions of branches; fruits exhibit large red or brown spots, occasionally becoming rings 3-4 centimeters in diameter

Apple Leaf Fleck, Bark Blister, Fruit Russet and Distortion

Found only to occur in New Zealand; leaves develop pale green flecks with some puckering and distortion; fruits are distorted and have areas of light brown russet, occasionally forming rings; dark purple eruptions may merge and form extensive cankers on the bark

Apple Maggot

Female apple maggot adults deposit eggs singly under the apple skin; damage is caused when this larvae burrow and feed on apple flesh; browning of the trails occurs as the apple responds to this injury and bacteria associated with maggots cause fruits to rot internally; larvae are cream-colored maggots with a blunt posterior and a tapered front end that contains two black mouth hooks

Apple Ringspot

Small, light-colored, reddish-brown areas appear under the bloom and only after fruit is 3 centimeters in diameter; as fruit ripens, the surface of the spots becomes rough and rusty and their margins intersected with small cracks; at harvest, dark, thin bands form around the rusty areas; incomplete rings form on the skin

Apple Rough Skin

Rough, dark brown corky areas on the fruit give it a scabby appearance; corky patches may appear as spots or partial rings; star-shaped cracks may form on the affected areas under cooler conditions; the first spur leaf will be puckered and flecked

Apple Russet Ring

Type A: Produces foliage that exhibits puckering and flecking, often in rings and lines; fruit develops slightly sunken rings, white or green in color, that become yellowish brown as the fruit ripens; Type B: No leaf symptoms but fruit shows russet areas usually in rings or incomplete circles

Bacterial Blossom Blast

Fruit buds infected in early bloom stop growing, turn brown and papery, and may drop off; later infections affect flower petals and stems, and fruit cluster bases turn brown or black; infection usually does not move beyond the base of the fruit cluster, however, sometimes fruit spurs are killed; flower symptoms may closely resemble fire blight but there is no bacterial ooze present

Bitter Rot

Rot on the fruit beginning as a small, light brown, circular lesions; as lesions enlarge, they change to dark brown and form sunken or saucer-shaped depressions; cream to salmon-colored spores may be produced on the surface of the lesions; flesh beneath the rot is V-shaped

Stink Bugs

Stink bugs damage the crop by feeding on the fruit; dimples or irregularly depressed areas develop on mature fruit; if the feeding occurs after maturity there is little external evidence other than excrement, which appears as small, brown, tear-shaped drops; internally they produce white, pithy areas that turn brown when fruit is peeled, usually concentrated near the stem end of the fruit

White Rot

Fruit symptoms are usually seen 4 to 6 weeks before harvest as small, slightly sunken brown spots that may be surrounded by a red halo; as the decay area expands, the core becomes rotten and eventually the entire fruits rot; the flesh is soft and watery under warm conditions; red-skinned fruit may bleach during the decay process and become light brown; infections on the wood develop around the lenticels as small spots or blisters that become watery and eventually black pyncidia appear


CREAM

Apple Maggot

Female apple maggot adults deposit eggs singly under the apple skin; damage is caused when this larvae burrow and feed on apple flesh; browning of the trails occurs as the apple responds to this injury and bacteria associated with maggots cause fruits to rot internally; larvae are cream-colored maggots with a blunt posterior and a tapered front end that contains two black mouth hooks

Bitter Rot

Rot on the fruit beginning as a small, light brown, circular lesions; as lesions enlarge, they change to dark brown and form sunken or saucer-shaped depressions; cream to salmon-colored spores may be produced on the surface of the lesions; flesh beneath the rot is V-shaped

Bull's Eye Rot

Most often noticed when infected fruit are removed from storage; lesions develop on the fruit with concentric rings of necrotic tissue; cream colored tufts or spores are sometimes present; infections occurs around petal fall or just before harvest


GREEN

Apple Brown Ringspot

Small yellow spots or chlorotic rings form on leaves between the veins sometimes forming longitudinal spots; fruits develop dark green spots which take on irregular shapes as the fruit matures; during and after harvest, brown ringspots are surrounded by green watery tissue; necrotic areas can develop on the fruit underneath blemished areas

Apple Chat Fruit

No leaf or bark symptoms present; symptoms are not noticeable until the June drop period when small dark green circular spots may form on the fruit surface, trees' growth is affected and is lacking in color; wet cool conditions cause to disease to manifest itself more

Apple Fruit Wrinkle

Depressions and pits develop on fruit followed by mild russeting; fruits are stunted and malformed with green stripes in the flesh; minute-sized fruit which develop from the base of the leaf petioles, are characteristic of the disease

Apple Green Crinkle

Symptoms appear in fruits only after they reach 1.0 to 1.5 centimeters in diameter; depression develop causing unequal growth malformations to occur; affected fruits become dwarfed; transport tissues under the sunken areas are green and show distortion but do not become necrotic; stony pits do not develop in the flesh; malformed fruits may only appear on one or two branches

Apple Russet Ring

Type A: Produces foliage that exhibits puckering and flecking, often in rings and lines; fruit develops slightly sunken rings, white or green in color, that become yellowish brown as the fruit ripens; Type B: No leaf symptoms but fruit shows russet areas usually in rings or incomplete circles

Brooks Spot

Irregular, slightly sunken dark green lesions usually at the calyx end of immature fruit; later lesions turn dark red or purple on red areas on the fruit and remain dark green on green or yellow areas

Quince Rust

Dark green fruit lesions which rarely sporulate develop on the surface of the fruit with necrotic tissues extending to the core; no foliar lesions develop


LIGHT

White Rot

Fruit symptoms are usually seen 4 to 6 weeks before harvest as small, slightly sunken brown spots that may be surrounded by a red halo; as the decay area expands, the core becomes rotten and eventually the entire fruits rot; the flesh is soft and watery under warm conditions; red-skinned fruit may bleach during the decay process and become light brown; infections on the wood develop around the lenticels as small spots or blisters that become watery and eventually black pyncidia appear


PINK

Bitter Rot

Rot on the fruit beginning as a small, light brown, circular lesions; as lesions enlarge, they change to dark brown and form sunken or saucer-shaped depressions; cream to salmon-colored spores may be produced on the surface of the lesions; flesh beneath the rot is V-shaped


PURPLE

Anthracnose

Small, circular, red or purple spots develop early on when fruit is moist and become elliptical, sunken, orange to brown areas in the bark as they grow; cracks develop between the diseased and healthy tissue causing a cream-colored acervuli to appear through cracks in the periderm; bark sloughs off older cankers exposing the wood beneath; most cankers are found on small twigs and branches

Blister Spot

Lesions 1-5 mm in diameter occurring only on the fruit, purplish black in color associate with stomata

Brooks Spot

Irregular, slightly sunken dark green lesions usually at the calyx end of immature fruit; later lesions turn dark red or purple on red areas on the fruit and remain dark green on green or yellow areas

San Jose Scale

Trees may be seriously damaged, resulting in reduced vigor, thin foliage, cracked or dying branches, and the eventual death of the tree; young trees may be killed before fruiting; infested fruit develop a reddish-purple ring surrounding each spot where a scale settles


RED

Anthracnose

Small, circular, red or purple spots develop early on when fruit is moist and become elliptical, sunken, orange to brown areas in the bark as they grow; cracks develop between the diseased and healthy tissue causing a cream-colored acervuli to appear through cracks in the periderm; bark sloughs off older cankers exposing the wood beneath; most cankers are found on small twigs and branches

Apple Depression

Leaves of infected 'McIntosh' trees suffer severe mosaic; irregular depressions develop on the fruit leaving the surface flat; these flat surfaces will take on a red color earlier than the fruit

Apple Fruit Blotch

Leaf veins and adjacent tissue develop cream-colored spotting; petals may be deformed with flecks or rings of red or brown pigment; bark develops blistering on the trunk and basal regions of branches; fruits exhibit large red or brown spots, occasionally becoming rings 3-4 centimeters in diameter

Apple Red Ring

Fruit develops red rings on the skins prior to the formation of the natural red color; the rings are less noticeable as the fruit matures

Apple Ringspot

Small, light-colored, reddish-brown areas appear under the bloom and only after fruit is 3 centimeters in diameter; as fruit ripens, the surface of the spots becomes rough and rusty and their margins intersected with small cracks; at harvest, dark, thin bands form around the rusty areas; incomplete rings form on the skin

Brooks Spot

Irregular, slightly sunken dark green lesions usually at the calyx end of immature fruit; later lesions turn dark red or purple on red areas on the fruit and remain dark green on green or yellow areas

San Jose Scale

Trees may be seriously damaged, resulting in reduced vigor, thin foliage, cracked or dying branches, and the eventual death of the tree; young trees may be killed before fruiting; infested fruit develop a reddish-purple ring surrounding each spot where a scale settles

White Rot

Fruit symptoms are usually seen 4 to 6 weeks before harvest as small, slightly sunken brown spots that may be surrounded by a red halo; as the decay area expands, the core becomes rotten and eventually the entire fruits rot; the flesh is soft and watery under warm conditions; red-skinned fruit may bleach during the decay process and become light brown; infections on the wood develop around the lenticels as small spots or blisters that become watery and eventually black pyncidia appear


WHITE

Apple Russet Ring

Type A: Produces foliage that exhibits puckering and flecking, often in rings and lines; fruit develops slightly sunken rings, white or green in color, that become yellowish brown as the fruit ripens; Type B: No leaf symptoms but fruit shows russet areas usually in rings or incomplete circles

Stink Bugs

Stink bugs damage the crop by feeding on the fruit; dimples or irregularly depressed areas develop on mature fruit; if the feeding occurs after maturity there is little external evidence other than excrement, which appears as small, brown, tear-shaped drops; internally they produce white, pithy areas that turn brown when fruit is peeled, usually concentrated near the stem end of the fruit


YELLOW

Apple Russet Ring

Type A: Produces foliage that exhibits puckering and flecking, often in rings and lines; fruit develops slightly sunken rings, white or green in color, that become yellowish brown as the fruit ripens; Type B: No leaf symptoms but fruit shows russet areas usually in rings or incomplete circles


No Distinct Discoloration

Apple Bumpy Fruit

Small yellow spots develop on the leaves on the veins and adjacent tissue; fruits become malformed with depressions and bumps

Apple Dapple Apple

No leaf or bark symptoms are present; small circular spots develop on fruit in mid-July and may produce large discolored areas; surface of affected areas is somewhat flattened and contains less cuticular wax

Apple Decline

Common in commercial cultivars; leaves may appear chlorotic; trees become stunted; bark becomes reddish brown; swelling and brown necrotic lines appear at or near the union; trees die after 4-5 years; small, deformed, premature fruit; foliage may be sparse and light green

Apple Flat Apple

Fruit becomes compressed from both the stalk and calyx side and appear flattened; fruit are smaller and tend to flatter; leaves on some infected varieties roll upward from the midrib

Apple Pandemis

Overwintered larvae feed on blooms and on the surface of young fruit causing them to drop or resulting in scarring and distortion; when apple pandemis tie leaves to fruit they cause shallow feeding scars; sometimes they feed for only a short time and produce several small circular holes in fruit

Apple Powdery Mildew

Fungus infects apple leaves, blossoms and fruit; commonly whitish, feltlife patches of fungal mycelium develops on the lower leaf surface; lesions appear as chlorotic spots on the upper leaf surface and may spread leaving the leaf with a white, mealy coating; leaf curling may occur; terminals and internodes are often stunted and covered with white lesions; with age, lesions turn gray or brown; may cause a net-like pattern of russetting on the fruit; fungus may appear on the twigs of infected branches

Apple Proliferation

Elongated stipules and leaf rosettes develop on the terminal parts of shoots; root systems form compact, felt-like masses which causes stunting; flowers may be delayed and have phyllody; leaves emerge earlier but are irregularly serrated and small; summer leaves are often chlorotic; fall foliage becomes purplish red early in the fall; fruits are small, few, incompletely colored and poorly flavored

Apple Ring Russeting

Leaves exhibit light green vein flecking on scattered leaves during some seasons; rings and oak-leaf patterns may develop on leaves of some Delicious types; fruit shows russet ring during most seasons

Apple Rosette

Growth of the trees in stunted; leaves form rosettes because of short internodes; leaves are small, brittle, curled upwards and deeply serrated; infected trees produce little or no fruit

Apple Rubbery Wood

Abnormal flexibility of stems and branches in 1 to 3 year old trees; trees assume a drooping habit; internodes are shortened; annual growth is reduced, sometimes even stunted; rootstock productivity, tree vigor and yield may be reduced

Apple Russet Wart

Russetted wart-like protuberances with superficial necrotic spots develop on the fruit surface; some varieties may have fruit that is malformed or develop necrotic russet rings on the fruit surface; leaves are small with chlorotic rings, spots or necrotic spots; symptoms appear on fruiting spurs and leaves of shoots

Apple Scab

Scab first appears on the undersides of new leaves as olive green to black spots which become brown and velvety with time; leaves may turn yellow and drop prematurely if the petiole becomes infected; long periods of wetness encourage the disease and may attack the fruit any time in its development; maturing fruit may crack and/or be misshapen and warty in appearance; early infections may result in blighting of blossoms and dropping of young fruits

Apple Scar Skin

Symptoms develop only on the fruit; water-soaked blotching appears on the stem end of infected fruits and on the sides of the fruit six weeks after pollination; two of three weeks later, scar tissue develops around the calyx end giving the fruit a corky texture; infected fruits remain small and hard and have an off-flavor

Apple Star Crack

Bark necrosis develops around the buds of one-year-old shoots; bark symptoms may be rough bark spots to open cankers; shoot tips often dieback; bud break can be premature or delayed and flowering can be abnormal; leaves often become chlorotic and cupped at the shoot tips in the fall; star-shaped cracks develop on the skin of the fruit; fruit is small and sometimes experience having slight depressions and rough skin

Apple Union Necrosis and Decline

Small, greenish yellow leaves, short internodes, amply flowering and many small bright fruits are characteristic symptoms; bark turns reddish with protruding lenticles; lateral leaves and buds die off, terminal shoots are short and clustered; trunk above the graft may swell; removing the thick and spongy bark at the scion/stock union reveals a distinct necrotic line; more suckers than normal develop from below the graft union; distinct black sunken line at union below the bark; trees may break at the union

Black Rot

Leaf lesions are frog-eyed in appearance, necrotic and may contain small black spherical pycnidia; infected fruit has extensive soft decay and rows of pyncidia; black pyncidia may develop on canker surface initiated by a large pruning cut or winter injury

Codling Moth

Two types of damage occur: strings and deep entries; strings are entries where larvae bore into the flesh a short distance before dying; deep entries occur when larvae penetrate the fruit skin, bore into the core and feed in the seed cavity; larvae may enter through the sides, stem end, or calyx end of the fruit; calyx entries are difficult to detect without cutting the fruit

European Canker

Reddish-brown lesions appear on small branches just below leaf scars developing into cankers with concentric ridges that may cause dieback of shoots in the spring; calyx rot of fruits can occur in years when rain precedes harvest; pruning wound infections are seen occasionally; may be confused with fire blight

European Red Mite

Severe mite infestations can cause bronzing of leaves, and may lead to small, poorly colored fruit and reduced bloom the following year; damage is relatively less severe on wide leaf varieties

Fire Blight

Decay is present in root, crown and/or lower trunk areas; advancing margin of infection sometimes orange in color, often a definite margin of infection; wood is slimy in appearance; decay may be restricted to interstem or rootstock only; milky droplets of ooze exuded on the surface on infected blossoms, cankers, fruits or shoots during moist conditions; infected tissues become scorched in appearance; blossom clusters wilt and collapse in late spring

Green Fruitworms

Young fruitworms larvae feed on leaves; fruit feeding usually begins about petal fall and continues until larvae have completed their development; these fruit are misshapen and have large, roughened, russeted cavities

Italian Pear Scale

Feeds directly on the wood of the tree affecting tree vigor and causing reduced fruit size; does not attack fruit; apple trees can withstand high populations before experiencing significant damage

Leafminers

Damage is restricted to foliage; larvae feed on cells between upper and lower epidermal layers of the leaf leaving only the epidermal layers; upper side of the leaf takes on a light, spotted appearance; heavy infestations cause premature defoliation and leaf function is impaired and fruit may fail in size and color

Lygus Bugs

Lygus bugs may feed on developing flower buds early in spring, causing the buds to exude gum and shrivel up with a heavy infestation; the most serious damage is by feeding directly on fruit; midseason feeding results in round pits, and late season feeding causes irregularly-shaped depressions that are similar to stink bug damage

Obliquebanded Leafroller

Larvae feed on flower parts and on fruit early in the season, causing deep depressions that eventually become rough and russeted by harvest; damage from the summer generation is usually more serious and results in superficial skin tunnels or small holes near the stem portions of the fruit

Omnivorous Leafroller

Larvae often web leaves into rolled protective shelters while feeding; they feed on leaves and on the surface of fruit, sometimes webbing one or more leaves to the fruit for protection; they chew shallow holes or grooves in the fruit surface, often near the stem end; larvae feed where fruit are touching so entire clusters can be damaged

Orange Tortrix

Most damage caused by larvae is feeding on the surface of fruit where they leave shallow, irregular scars; they usually feed within a fruit cluster; occasionally they tie a leaf to the fruit's surface and feed under it

Rosy Apple Aphid

Aphids cluster on leaves of fruit spurs and growing shoots where they cause severe leaf curling; fruits on heavily infested fruit spurs fail to properly develop and become misshapen

Webspinning Spider Mites

Mites feed on leaves, removing cell contents and gradually giving leaves a finely stippled appearance; heavy infestations result in severe bronzing of foliage and premature defoliation; fruit on heavily infested trees fail to color and size properly and fruit production for the following year may be lowered

Western Tussock Moth

A heavy infestation will destroy all spring growth; larvae take shallow bites out of newly set, young fruit; these injured areas eventually scab over and russet; infestations are spotty and may be isolated in certain areas of an orchard

Wooley Apple Aphid

Main injury to young and mature trees is stunting due to the formation of root galls; if populations are high, honeydew and sooty mold will also be problems and aphids may enter the calyx end of the fruit