Pome fruitsPome fruits► Grown in the temperate zones in both hemispheres. Grown in the temperate zones in both hemispheres.

Most production is in the cooler sections of US, Most production is in the cooler sections of US, Canada and Europe. Not below Memphis and Fort Canada and Europe. Not below Memphis and Fort Smith AR.Smith AR.

► Apples #1 pome fruit with most production in the Apples #1 pome fruit with most production in the Pacific NW, in the valleys where climate is dry and Pacific NW, in the valleys where climate is dry and the crops are irrigated.the crops are irrigated.

► 1991 – 9,871 million pounds1991 – 9,871 million pounds► Leading States 71% of total productionLeading States 71% of total production► Washington Washington 4,300 million lbs 4,300 million lbs► New York New York 1,050 million lbs1,050 million lbs► MichiganMichigan► Calif.Calif.► PA, VA, NC, WVA, OR, ID, OH, and ILPA, VA, NC, WVA, OR, ID, OH, and IL

Most popular varietiesMost popular varieties

► Red and Yellow DeliciousRed and Yellow Delicious► McIntoshMcIntosh► Rome BeautyRome Beauty► YorkYork► JonathanJonathan

Recently Granny Smith, Gala, Fiji Recently Granny Smith, Gala, Fiji

► Fresh market = highest prices, remainder of Fresh market = highest prices, remainder of crop is process for juice, sauce, jelly or jam.crop is process for juice, sauce, jelly or jam.

Apple DiseasesApple Diseases

►Apple ScabApple Scab►Fire BlightFire Blight►Cedar Apple RustCedar Apple Rust►Black RotBlack Rot

Apple ScabApple Scab

Pathogen – Pathogen – ►Venturia inequalisVenturia inequalis –sexual –sexual►Spilocaea pomiSpilocaea pomi -asexual -asexual►Responsible for crop failures in the late Responsible for crop failures in the late

1800s. Present in all countries where 1800s. Present in all countries where apples are grown. Not a problem in apples are grown. Not a problem in dry, irrigated locations, but where cool dry, irrigated locations, but where cool moist wet spring months are commonmoist wet spring months are common

James Peale, 1824

Symptoms –Symptoms –► Fruit, leaves, leaf petioles, and young twigs Fruit, leaves, leaf petioles, and young twigs

attacked causing scabby lesions in which attacked causing scabby lesions in which tissues may be killed.tissues may be killed.

► LeafLeaf - spots, black in color and appear on - spots, black in color and appear on both surfaces and leaf may curl or distortboth surfaces and leaf may curl or distort

► FruitFruit ScabsScabs - appear similar on fruit but the - appear similar on fruit but the fungus stimulates cork formation beneath fungus stimulates cork formation beneath spots that may cover the fruits and result in spots that may cover the fruits and result in severe fruit disfigurationsevere fruit disfiguration

► Twigs Twigs – infections easily overlooked as the – infections easily overlooked as the lesions look like enlarged lenticelslesions look like enlarged lenticels

► Fungus attacks only current season Fungus attacks only current season growthgrowth

SymptomsSymptoms

SymptomsSymptoms

SignsSigns pseudothecia

SignsSigns

SymptomsSymptoms

Economic impact Economic impact

►Greater than most diseases because:Greater than most diseases because:►Crop reduction (Defoliation- Crop reduction (Defoliation-

weakening)weakening)►Lowering of fruit gradeLowering of fruit grade►Foliage lossFoliage loss► Increase in production costs – Increase in production costs –

Fungicides – Prior to fungicides, total Fungicides – Prior to fungicides, total fruit drop – appeared dormant in June.fruit drop – appeared dormant in June.

Disease CycleDisease Cycle► Fungus overwinters in leaves on ground and sometimes on Fungus overwinters in leaves on ground and sometimes on

apple budsapple buds► Late fall – spring pseudothecia are produced in leaves – Late fall – spring pseudothecia are produced in leaves –

Primary infection in new growthPrimary infection in new growth► Olive, two-celled ascospores –Primary Inoc. Ejected into airOlive, two-celled ascospores –Primary Inoc. Ejected into air► Conidia produced in apple bud scales Conidia produced in apple bud scales ► Ascospores and conidia infect flowers and leavesAscospores and conidia infect flowers and leaves► Secondary cycle – conidia produced in primary lesions, 7-9 Secondary cycle – conidia produced in primary lesions, 7-9

days after infectiondays after infection► Spread by splashing rain and by wind.Spread by splashing rain and by wind.► Infected fruit may not show symptoms until storage after Infected fruit may not show symptoms until storage after

several monthsseveral months► Inoculum level in spring may be high after spray –because Inoculum level in spring may be high after spray –because

overwintering in leavesoverwintering in leaves

Disease Cycle – Apple ScabDisease Cycle – Apple Scab

ControlControl

►Hosts – Cultivated apple and crab Hosts – Cultivated apple and crab apple species. Not to pearapple species. Not to pear

►Resistance Resistance ►Sanitation – not feasibleSanitation – not feasible►Chemical - #1, protectant – prevent Chemical - #1, protectant – prevent

spores from germinating, postinfection spores from germinating, postinfection fungicides – some resistance in fungal fungicides – some resistance in fungal populationspopulations

Cedar Apple RustCedar Apple Rust

► Pathogen – Pathogen – Gymnosporangiuim juniperi-Gymnosporangiuim juniperi-virginianae virginianae BasidiomyceteBasidiomycete

► Name comes from fact that red cedar Name comes from fact that red cedar ((Juniperus viginianaeJuniperus viginianae) is alternate host) is alternate host

► Other species cause quince rust and Other species cause quince rust and hawthorn rusthawthorn rust

► Economic impact Economic impact – due to apple tree – due to apple tree defoliation that results in fruit yield and size defoliation that results in fruit yield and size reduction and also a reduction in tree vigorreduction and also a reduction in tree vigor

Symptoms –Symptoms –

Apple Apple ► LeafLeaf - bright yellow leaf spots that turn orange as - bright yellow leaf spots that turn orange as

enlarge and age. enlarge and age. ► Fruit and twigFruit and twig – infections occur – infections occur► These symptoms caused by fungus aecial stage.These symptoms caused by fungus aecial stage.

CedarCedar► LeafLeaf - Brown to reddish brown leaf galls -During - Brown to reddish brown leaf galls -During

periods of rain, galls produce orange, gelatinous spore-periods of rain, galls produce orange, gelatinous spore-horns from the gall surface that contain masses of horns from the gall surface that contain masses of teliospores. teliospores.

► Teliospores Teliospores – germinate and each cell produces 4 – germinate and each cell produces 4 basdiospores that are airborne to applesbasdiospores that are airborne to apples

Symptoms –Symptoms –

Disease CycleDisease Cycle

Two host and three fruiting structuresTwo host and three fruiting structuresApple, cedarApple, cedar - telia, aecia, and pycnia - telia, aecia, and pycnia

OW in reddish brown galls – cedar apples in cedar treeOW in reddish brown galls – cedar apples in cedar tree Wet in spring – horns with teliospores, each =produces 4 Wet in spring – horns with teliospores, each =produces 4

basidiosporesbasidiospores Air currents (3-5 kilometers) – germ tubes – leaf and fruit of Air currents (3-5 kilometers) – germ tubes – leaf and fruit of

apples, temp and wetting conditions 4-8 d old leaves - apples, temp and wetting conditions 4-8 d old leaves - spermagonia that is fertilized by compatible spermatia = spermagonia that is fertilized by compatible spermatia = production of aecia production of aecia

July and August windborne aeciospores (produced in chains) July and August windborne aeciospores (produced in chains) from apple infect cedar leaves 1-3 weeks = rust lesion from apple infect cedar leaves 1-3 weeks = rust lesion

fungus grows in tissue in winter18 months after infection fungus grows in tissue in winter18 months after infection production of gallsproduction of galls

DiseaseDisease Cycle Cycle

Control Control

Eradication 1-2 miles of orchards – red Eradication 1-2 miles of orchards – red cedars, 4-5 miles more effectivecedars, 4-5 miles more effective

Resistance Resistance

Chemical Chemical

FireblightFireblight

Pathogen – Pathogen – Erwinia amylovora – Erwinia amylovora – bacteriumbacterium► This was the first plant disease proven to be caused by This was the first plant disease proven to be caused by

a bacteriuma bacterium► Pear industry in Eastern U.S. was essentially wiped out Pear industry in Eastern U.S. was essentially wiped out

by this disease in 1900’sby this disease in 1900’s► Pear is considerably more susceptible than apple, - Pear is considerably more susceptible than apple, -

most destructive disease of applemost destructive disease of apple

► Economic impact Economic impact – Results from killing of flowers, – Results from killing of flowers, fruit spurs, twigs and girdling of large branches and fruit spurs, twigs and girdling of large branches and trunks that results in death of the treestrunks that results in death of the trees

► Young trees in nursery or orchard can be killed Young trees in nursery or orchard can be killed in a single season.in a single season.

► HostsHosts – over 75 rosaceous plant species are – over 75 rosaceous plant species are susceptiblesusceptible

Symptoms Symptoms

► Flower and twig Flower and twig – blight appears in spring, – blight appears in spring, blackening of flowers and leaves = curled blackening of flowers and leaves = curled leaves hanging from twigs and small branchesleaves hanging from twigs and small branches

► Fruits Fruits – first as watersoaked lesion, then – first as watersoaked lesion, then mummifies and turn black and may be tree for mummifies and turn black and may be tree for several monthsseveral months

► Fruit spurs and terminal twigs Fruit spurs and terminal twigs – Infections – Infections and symptoms progress to supporting and symptoms progress to supporting branches where cankers are formed.branches where cankers are formed.

► SignSignDuring humid conditions, milky bacterial During humid conditions, milky bacterial ooze may appear on surface of infected part – ooze may appear on surface of infected part – rod-shaped with flagellarod-shaped with flagella

SymptomsSymptoms

Apple Shoot

Pear Blossom

Symptoms (Shepard’s Crook)Symptoms (Shepard’s Crook)

SymptomsSymptoms

Burnt Appearance Diseased shoot on left

Disease CycleDisease Cycle► Bacteria overwinter in Bacteria overwinter in

canker margins in branchescanker margins in branches► Warm spring weather = Warm spring weather =

multiplicationmultiplication► Sticky bacterial exudates is Sticky bacterial exudates is

present insects are attracted present insects are attracted and pickup ooze on their and pickup ooze on their bodies and transfer to bodies and transfer to flowers where new infections flowers where new infections take placetake place

► Splashing rain may also Splashing rain may also spread the bacteria (enter spread the bacteria (enter through natural and wound through natural and wound openings)openings)

Disease Cycle – Fire BlightDisease Cycle – Fire Blight

ControlControl3 Areas of Importance3 Areas of ImportanceI. Reducing bacterial inoculumI. Reducing bacterial inoculum► Removal by pruning the overwintering Removal by pruning the overwintering

cankerscankers► Weekly inspection of orchards in Weekly inspection of orchards in

summer, and removal of infected spurs summer, and removal of infected spurs and terminalsand terminals

► Disinfect toolsDisinfect toolsII. Properly timed application of bactericides II. Properly timed application of bactericides

during flowering to control blossom blight during flowering to control blossom blight phasephase

► CuCu► Streptomycin 2-3 applicationsStreptomycin 2-3 applicationsIII. Insect control esp. aphids and plant bugs to III. Insect control esp. aphids and plant bugs to

prevent infectionsprevent infectionsIV. Avoid planting susceptible cultivars – IV. Avoid planting susceptible cultivars – V. Apples more resistantV. Apples more resistantVI. Over stimulation (succulent growth part. VI. Over stimulation (succulent growth part.

Susc.) with high N should be avoidedSusc.) with high N should be avoided

Black RotBlack Rot

►Pathogen – Pathogen – Botryosphaeria obtuseBotryosphaeria obtuse--

Economic EffectsEconomic Effects►Limb Canker phase is most important in Limb Canker phase is most important in

the northeastern and north central the northeastern and north central apple-growing regions of the United apple-growing regions of the United StatesStates

►Leaf Spot and fruit rot phase are most Leaf Spot and fruit rot phase are most important in the southeastimportant in the southeast

Symptoms Symptoms – – Appear 1 to 3 weeks after first petal fallAppear 1 to 3 weeks after first petal fall-leaf infections begin as small purple flecks rapidly enlarging to 1/8 to -leaf infections begin as small purple flecks rapidly enlarging to 1/8 to

1/4 in. diameter.1/4 in. diameter.-Margins remain purple, center turns brown; “frog eye appearance”-Margins remain purple, center turns brown; “frog eye appearance”

Infections on young fruitInfections on young fruit-reddish flecks, developing into purple pimples-reddish flecks, developing into purple pimples-enlarge to dark brown necrotic areas-enlarge to dark brown necrotic areas

Infections on more mature fruitInfections on more mature fruit-Black, irregularly shaped-Black, irregularly shaped-surrounded by red halo -surrounded by red halo -enlarging; characterized by series of concentric rings alternating -enlarging; characterized by series of concentric rings alternating black to brownblack to brown

Infected fruit mummify and remain attached to treeInfected fruit mummify and remain attached to treeLimbs and branchesLimbs and branches

-reddish brown and slightly sunken cankers large and small-reddish brown and slightly sunken cankers large and small-branches weak & break with heavy crop load-branches weak & break with heavy crop load

SymptomsSymptoms

Symptoms Symptoms

Symptoms Symptoms

Disease CycleDisease Cycle

-Over-winters in dead bark, twigs, cankers, and mummified -Over-winters in dead bark, twigs, cankers, and mummified fruitfruit

-Ascospores (spring) and conidia released during rainfall; -Ascospores (spring) and conidia released during rainfall; washed or blown onto fruit or foliagewashed or blown onto fruit or foliage

-Sepal infection occurs after bud break-Sepal infection occurs after bud break

-Fruit infection occurs during growing season-Fruit infection occurs during growing season

-Leaf infection common after petal fall-Leaf infection common after petal fall

-Early season infection may result in fruit drop-Early season infection may result in fruit drop

Control Control

-Removing dead wood, mummies & -Removing dead wood, mummies & cankers from treescankers from trees

-Current season prunings should be -Current season prunings should be removed form the orchard or chopped removed form the orchard or chopped with a flail mowerwith a flail mower

-Fungicides, applied from silver tip until -Fungicides, applied from silver tip until harvest required to control diseaseharvest required to control disease