Plant Health Management for Backyard Stone Fruit Plantings (Peaches, Cherries, and Plums)

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Plant Health Management for Backyard Stone Fruit
Plantings (Peaches, Cherries, and Plums)
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• Prepared by
• Mike Ellis Professor and
  Extension Specialist
  and
  Omer Erincik
  Graduate Research Assistant
• Department of Plant Pathology
  
  The Ohio State University
  OARDC/OSUE
  Wooster, OH, 44691

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Brown rot

• Symptoms
• Small, circular, light brown spots expand rapidly
  on ripening fruit, rotting the fruit within a day
  or two.
• Under wet conditions, ash-gray tufts of fungus
  form on the surface of infected fruit.
• Rotted fruit may fall from the tree or remain
  attached as shriveled mummies.
• Blossoms wilt, turn brown, and persist into
  summer.
• Blossom infections can invade the attached shoots
  or twigs and cause cankers (areas of dead bark).
  Cankers may enlarge and kill the branch or twig.

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Brown rot

• Disease Development
• affects all stone fruit
• caused by the fungus Monilinia fructicola.
• The fungus overwinters in the previous year's
  diseased plant parts such as mummies, on the tree
  or ground and in cankers on the twigs.
• In April, May and June, the fungus produces
  millions of spores. These spores are spread by
  splashing rain and by wind.
• A free film of water on leaves and fruit is
  required for the spores to germinate and
  infection to occur.
• Wounded fruit are most readily infected.
• Fruit rot symptoms become most evident as the
  fruit start to mature.

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Peach leaf curl and plum pockets

• Symptoms
• In spring, developing leaves become severely
  distorted (thickened and puckered), and have a
  reddish or purple cast.
• Later, as spores form on the leaf surface, the
  leaves become powdery gray in color.
• Shortly after this, the leaves turn yellow or
  brown and drop.
• Diseased twigs become swollen and stunted, and
  may have a slight golden cast. They usually
  produce curled leaves at their tips.
• Diseased fruit have shiny, reddish, raised, warty
  spots. They drop shortly after they are infected.

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Peach leaf curl and plum pockets

• Disease development
• affects peaches and plums, but not cherry.
• caused by the fungus Taphrina deformans.
• The fungus survives the winter as spores
  (conidia) on infected bark and buds.
• During cool, wet spring weather the conidia
  infect new leaves as they emerge from the buds.
• Host plant tissues are susceptible for only a
  short period. As the tissues mature they become
  resistant.
• The disease is not active later in the growing
  season.
• Rain (free water) is necessary for infection.

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Peach scab

• Symptoms
• Small, round, olive-green spots generally develop
  near the stem end or on the side of the fruit
  exposed to the sun.
• Spots may merge to form large, irregular blotches
  that turn velvety, dark olive-green or black.
• Severely infected fruit may become misshapen, or
  crack open, and drop prematurely.
• Small, round, and yellowish-green to
  yellowish-brown spots develop on the underside of
  the leaf.
• Diseased leaf tissue may dry up and drop out,
  leaving "shot-holes." If the season is wet,
  scab-infected leaves usually drop early.

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Peach scab

• Disease development
• affects only peaches.
• caused by the fungus Cladosporium carpophilum.
• The fungus overwinters on bark and in twigs
  infected the previous year.
• During spring and summer, large numbers of
  microscopic spores (conidia) are formed on twig
  lesions.
• The spores are spread by splashing rain or
  windblown mist to developing fruit, twigs, and
  leaves.
• Spore germination and fungus growth is most rapid
  at 65-75 degrees F.
• The fruit remain susceptible until harvest
  however,the disease is usually not observed until
  the fruit are well grown.

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Bacterial spot

• Symptoms
• On leaves
• Small, irregular to angular, deep purple to
  rusty-brown or black colored spots form on the
  leaves.
• In time, the centers dry and tear away leaving
  ragged "shot-holes."
• When several spots merge, the leaf may appear
  scorched, blighted, or ragged.
• Badly infected leaves may turn yellow and drop
  early.

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Bacterial spot

• Symptoms
• On fruit
• Small, round olive-brown to black spots form on
  the fruit.
• They are usually sunken and frequently surrounded
  by a water-soaked margin.
• On some varieties the spots may exude a yellowish
  gum after rainy periods.
• Skin cracking and pitting may occur near the
  spots during fruit enlargement.

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Bacterial spot

• Disease development
• affects all stone fruit.
• caused by the bacterium Xanthomonas pruni.
• The bacteria overwinter in twigs that are
  infected late in the season about the time leaves
  are shed.
• In the spring, bacteria ooze out from these
  diseased plant parts onto the plant surface.
• The bacteria are then spread by windblown or
  splashing rain and can result in new infections
  throughout the growing season.
• Bacteria enter the tissues through natural
  openings (stomata or lenticels) when surface
  moisture is present.
• Warm temperatures (70-85 degrees F) with light
  rains, heavy dews, and windy weather are most
  conducive for disease development and spread.

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Cherry leaf spot

• Symptoms
• Small circular purple spots appear on the upper
  surface of the leaf.
• Whitish-pink masses of sticky spores (conidia)
  form within the spots on the undersides of
  infected leaves during periods of damp weather.
• Later, the centers of the spots may dry up and
  drop out, giving a "shot-hole" appearance.
• The most conspicuous symptom, especially on sour
  cherries, is the golden yellowing of older
  infected leaves before they drop off.
• Spots similar to those on the leaves may also
  form on leaf petioles and fruit pedicels, causing
  fruit to ripen unevenly. Spots usually do not
  form on fruit.

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Cherry leaf spot

• Disease development
• affects only sweet and tart cherry
• caused by the fungus, Blumeriella jaapii .
• The fungus overwinters in dead leaves on the
  ground.
• In spring, the fungus produce spores
  (ascospores) during rainy periods for about six
  to eight weeks, starting at petal fall.
• These spores are spread by wind or splashing rain
  drops to healthy leaves and serve as primary
  inoculum for the disease.
• The spores penetrate the leaf through stomata
  (natural openings) on the underside of the leaf.
  The small purple spots soon appear on the upper
  surface.

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Cherry leaf spot

• Disease development
• Masses of secondary or summer spores (conidia)
  are produced in the spots on the underside of the
  leaf.
• Conidia are spread to other leaves by splashing
  raindrops and are capable of causing new
  infections .
• Serious leaf spot damage (defoliation) usually
  occurs in years with numerous rainy periods
  throughout late spring and summer.

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Powdery mildew

• Symptoms
• On leaves and shoots
• Spots first appear as circular, white patches on
  leave surface.
• The white spots are growth of the fungus
  mycelium and its spores.
• Lesions spread rapidly, eventually, they may
  cover the entire leaf.

• Diseased leaves often fail to unfold normally,
  while those of new shoots become narrow,
  distorted, blighted, and stunted.

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Powdery mildew

• Symptoms
• On fruit
• The disease first appear as white circular spots
  on young fruit.
• The spots enlarge and eventually, may cover much
  of the fruit.
• Later, the skin of the fruit under the spot turns
  pinkish, and the fungus and its spores disappear.
  
• Eventually the skin becomes leathery or hard,
  turns brown, and may crack.

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Powdery mildew

• Disease development
• affects all stone fruit.
• Pathogens
• Podospaera clandestinaon cherry
• Sphaerotheca pannosa..on peach and other
  stone fruit.
• The former overwinters as in fruiting bodies
  (cleistothecia) on the barks and latter
  overwinters as mycelium dormant buds of
  previously infected twigs..
• In spring, the fungi initiate their growth and
  produce spores which are carried by wind or rain
  to leaves, twigs and fruit.
• Both leaves and fruit are susceptible to
  infection when young but they become resistant as
  they mature.
• Most infections occur at moderate temperatures
  and high humidity.
• Free water is not required.
• The fungi produce secondary spores later in the
  growing season cause secondary infections.

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Management of fruit and leaf diseases

• Free water (wet conditions) is required for most
  fungal pathogens (except Powdery mildew) to
  infect plants. Any practice that promotes faster
  drying of fruit and foliage is beneficial for
  disease control.
• Site selection
• Select a site with good air movement all-day sun
  light, and good soil drainage.
• Do not plant trees in shaded areas.

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Management of fruit and leaf diseases

• Canopy management
• Control timing and amount of nitrogen fertilizer
  to prevent excessive growth.
• Prune out and destroy all dead or diseased shoots
  and limbs while trees are dormant.
• Prune healthy growth to improve air movement and
  sunlight penetration, to minimize shading and
  decrease drying time of leaves and fruit during
  the growing season.

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Management of fruit and leaf diseases

• Sanitation
• Remove all infected fruit and mummies as well as
  blighted twigs from the tree.
• Rake out and dispose of fruit mummies and leaves
  (cherry leaf spot) that have fallen to the
  ground.
• These sanitation measures will reduce the number
  of spores that can initiate these diseases.
• Fungicides
• On susceptible varieties, fungicides may be
  required to obtain an acceptable level of disease
  control.

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Management of fruit and leaf diseases

• Disease Resistance
• For most disease, resistance is not available.
• For bacterial spot and powdery mildew,
  susceptible varieties should be avoided.

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Susceptibility of common peach cultivars to
Bacterial spot

• Resistant Candor, Cresthaven, Earliglo, Encore,
  Harbelle, Harbinger, Harbrite, Harken,
  Jerseydawn, Norman, Pekin, Ranger, Redkist,
  Redskin
• Tolerant Biscoe, Earlirio, Garnet Beauty,
  Glohaven, Jerseyqueen, Loring, Rio-Oso-Gem,
  Sentinel, Springold, Summerglo, Sunqueen,
  Sunshine, Surecrop, Topaz
• Susceptible Autumnglo, Blake, Harmony,
  Jerseyland, Redcrest, Redhaven, Sweet Sue,
  Suncrest, Sunhigh, Triogem, Tyler, Velvet,
  Washington

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Peach canker

• Symptoms
• In early spring, gummy drops of sap first appear
  around wounded bark
• The inner bark begins to break down, causing the
  cankered surface.
• During wet periods spores ooze out of these
  cankered surfaces in tiny orange or amber
  colored, curled strands.
• During the summer, healthy bark grows over the
  edges of the narrow, oval shaped cankers.
• Over a period of years, a series of dead callus
  ridges form as the canker gets larger.
• Eventually, the canker may completely surround a
  branch. The portion of the branch above the
  canker then dies.

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Peach canker

• Disease development
• affects all stone fruit, but most severe on
  peach.
• caused by the fungi, Cytospora leucostoma and
  Cytospora cincta.
• These fungi are weak pathogens and generally do
  not attack healthy, vigorous peach bark. Winter
  injury, insect damage, and mechanical injury are
  common types of wounds serving as entry points.
• The fungi survive the winter in cankers or in
  dead wood.
• During spring and summer, spores produced in the
  cankers are spread by wind and rain to wounds on
  the same or nearby trees.
• Infection and canker development depend on
  temperature and the species of fungus involved.
  Cytospora cincta is favored by lower temperatures
  than Cytospora leucostoma.

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Management of peach canker

• Site selection
• Trees should be planted in sites with well
  drained soil and good air circulation. This
  promotes faster drying.
• Do not plant trees in shaded areas.
• Do not plant new peach trees near established
  trees with canker.
• Pruning
• Prune young trees carefully to avoid weak,
  narrow-angled crotches. Narrow-angled crotches
  are frequent sites of breakage and winter injury.
  
• Delay pruning until early spring. This promotes
  quick healing and avoiding winter injury.
• Sanitation
• Remove and destroy cankered limbs, branches and
  dead wood while pruning. These limbs or branches
  serve as a reservoir for the disease causing
  fungi.

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Management of peach canker

• Promote vigorous, healthy peach trees
• Do not over-fertilize late in the season. Winter
  injury is more common on these trees because
  winter hardening is delayed.
• Trickle irrigation during dry period help to
  increase resistance to the disease
• Avoid mechanical and insect injury
• Maintain a good control program for other
  diseases and insect pests, especially borers
• Protect trees from winter injury
• White latex paint applied to the southwest side
  of trunks and lower scaffold branches may help
  avoid cold injury during winter.

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Black knot

• Symptoms
• The fungus mainly affects twigs, branches, and
  fruit spurs.
• On infected plant parts, abnormal growth of bark
  and wood tissues produce small, light-brown
  swellings.
• In late spring, the rapidly growing young knots
  have a soft (pulpy) texture and become covered
  with a velvety, olive-green growth of the fungus.
  
• In summer, the young knots turn darker and
  elongate.
• In fall, they become hard, brittle, rough and
  black.
• During the following growing season, the knots
  enlarge and gradually encircle the twig or
  branch.

• Smaller twigs usually die within a year after
  being infected. Larger
• branches may live for several years before
  being girdled and killed by
• the fungus.

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Black knot

• Disease development
• affects only plum and cherry.
• caused by the fungus, Apiosporina morbosa.
• The fungus overwinters in knots on twigs and
  branches or in the infected wood.
• In spring, the fungus produces spores on the
  surface of the knots.
• These spores are ejected into the air during
  rainy periods and are blown for moderate
  distances by wind currents.

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Black knot

• Disease development
• Only succulent green twigs of the current
  season's growth are susceptible to infection.
• Only a few hours of rain are apparently required
  for infection at temperatures above 55 degrees F.
• Knots may become visible by the late summer of
  the year of infection but often are not noticed
  until the following spring.
• The fungus continues to grow in infected wood
  during spring and fall, causing the knots to
  elongate several inches each year and eventually
  girdle affected twigs and branches.

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Management of Black knot

• Site selection
• Trees should be planted in sites with well
  drained soil and good air circulation. This
  promotes faster drying.
• Do not plant trees in shaded areas.
• Avoid planting trees next to or downwind from an
  orchard with a black knot problem.
• Sanitation
• infected twigs should be pruned out by making
  cuts 6 inches below the knot before bud break and
  destroyed by burning or burying .
• This sanitation measure will reduce the number of
  spores that can initiate the disease.
• Fungicides
• On susceptible varieties, fungicides may be
  required to obtain an acceptable level of disease
  control

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Management of Black knot

• Use disease resistant plum varieties
• Most commercially grown plum varieties, including
  Stanley and Damson, are highly susceptible to
  black knot.
• Early Italian, Brodshaw, Fallenburg, Methley and
  Milton are moderately susceptible.
• Shiro, Santa Rose, and Formosa are slightly
  susceptible
• President is apparently resistant to black knot.
• Japanese varieties of plums are generally less
  susceptible than most American varieties.

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Phytophthora root rot

• Symptoms
• Above ground
• Affected trees exhibit poor terminal growth,
  sparse and cholorotic foliage, and progressive
  decline.
• Some trees exhibit early reddish discoloration of
  leaves in late August or early September.
• Eventually, infected trees usually die.
• Below ground
• A diagnostic reddish-brown discoloration of the
  inner bark and wood can be observed on the crown
  or main roots of infected plants.
• A sharp line separates the reddish-brown
  (diseased) and white (healthy) portion of the
  crown.

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Phytophthora root rot

• Disease development
• caused by several species of the fungus
  Phytophthora.
• The fungus overwinters and persists in soil for
  many years.
• The fungus requires extremely wet or saturated
  soils in order to infect and cause significant
  damage thus good soil drainage is important for
  control.
• When soils are saturated, the fungus produces
  spores, called zoospores. Zoospores use flagella
  to swim to susceptible plant tissue where they
  cause infection.
• The longer the period or periods of soil
  saturation, the greater the risk of infection.
• Some species may also be introduced to the
  orchard on contaminated planting stock or through
  movement of contaminated soil.

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Management of Phytophthora root rot

• Proper site selection
• Plant in well-drained soil.
• Plant on raised planting beds if soil does not
  have excellent drainage.
• Select a site that does not have a previous
  history of problems with the Phytophthora root
  rot.
• Use disease resistant rootstocks
• Mazzard cherry rootstocks are more resistant than
  Mahaleb cherry rootstocks to some species of
  Phytophthora.
• the effectiveness of resistant rootstocks is
  limited since resistant rootstocks control some
  species of Phytophthora but not others.
• On peach most currently available rootstocks are
  susceptible.

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Using Fungicides For Stone Fruit Disease Control

• Fungicides are very important for disease control
  in commercial stone fruit production, and may be
  required in backyard stone fruit plantings if
  highly susceptible varieties are grown however,
  the emphasis for disease control in backyard
  plantings should be placed on the use of disease
  resistance and the various cultural practices
  previously mentioned.

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• For backyard growers that do require fungicides
  in the disease management program, fungicide
  recommendations are available for stone fruit in
  Bulletin 780 Controlling Disease and insects In
  Home Fruit Planting.

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Selected literature for backyard fruit production
and plant health management

• Bulletin 591. Growing and Using Fruit at Home
• Bulletin 780. Controlling Diseases and Insects
  in Home Fruit Planting
• Midwest Tree Fruit Pest Management Handbook
• These can be obtained through your county
  extension agent or the Extension Publications
  Office, The Ohio State University, 385 Kottman
  Hall, 2021 Coffey Road, Columbus, Ohio, 43210-1044

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• To get more information about plant diseases
  visit the websites below.
• http//www.ag.ohio-
• state.edu/plantdoc/extension.php
• http//www.ohioline.ag.ohio-state.edu