Apple and Pear Diseases Flashcards
When were apples brought to North America?
1600’s
How many apple cultivars make up 90% of US production?
10
Who are the top two producers of apples in the world?
China
USA
What is the world production of apples in pounds?
125 billion
What is the current apple acreage in the USA?
430,000
Apple trees are composed only of rootstock? (T/F)
false
rootstock and scion (cultivar)
Does Apple Mosaic Virus cause Rose Mosaic?
Yes
How is apple chlorotic leaf spot virus transmitted?
grafting
no vector or seed transmission reported
Where can apple stem pitting virus be found in the plant?
xylem
Do phytoplasmas effect apples and pears?
yes
How is apple proliferation transmitted?
grafting
leafhoppers
What causes apple proliferation?
phytoplasma
Is apple proliferation in the US?
No, but in Europe
Where is the apple proliferation phytoplasma limited to in the plant?
phloem
What broom symptom does apple proliferation cauase?
Witches broom
What is one of the most important apple diseases in europe?
apple proliferation
What symptom at grafting point does apple proliferation cause?
black line between stock and cultivar
what is the most important type of pathogen for apple?
bacteria
What is the pathogen that causes fire blight?
Erwinia Amylovora
What is Erwinia amylovora?
a bacteria that causes fire blight disease
Is Erwinia amylovora native to North America?
Yes
When was Erwinia amylovora introduced to Europe?
1950-1960
Where does Erwinia amylovora overwinter?
Only in host plants
What was the first bacteria shown to be pathogen to plants and when?
Erwinia amylovora in 1885
Where does fire blight overwinter?
in cankers
Where do fire blight cankers occur?
on infected limbs or the trunk
What color is the bacterial ooze in fire blight cankers?
white to yellow
Does fire blight also cause blossom blight on apple and pear trees?
yes
Does fire blight cause rootstock blight?
Yes
Will fire blight infect whole limbs?
Yes
Does fire blight occur on Bradford pear?
Yes
Is Apogee used in control of fire blight?
Yes but experimentally
What is the scientific name of the cultivated apple?
Malus Domestica
What family is the cultivated apple in?
Rosaceae
How does an apple a day keep the doctor away?
Flavonoids
What is the average apple yield per acre?
9800 lbs
What percentage of apple production happens in the USA?
7%
What was the 2002 US apple production in lbs?
8.5 billion
How many acres of apple trees are in the US?
430,000
How many calories does the average apple contain?
80
How many grams of fiber in an apple?
5
How many pounds of apples does the average consumer eat per year?
45.2 lbs
What is the Scion?
The apple cultivar
What is the Bromoviridae Ilavirus?
The apple mosaic virus
How is the apple mosaic virus transmitted?
mechanical,
grafting
pollen
NOT SEED TRANSMITTED
Where in the world is the apple mosaic virus found?
worldwide
Which virus shows rose mosaic symptoms in apples?
apple mosaic virus
What is the Betaflexiviridae Trichovirus?
apple chlorotic leaf spot virus
Where is apple chlorotic leaf spot virus found in the world?
worldwide
How is the apple chlorotic leaf spot virus transmitted?
No transmission by vectors or seed reported
What is a symptom of the apple chlorotic leaf spot virus?
Pear ring pattern disease
What is a symptom of apple stem pitting virus?
Xylem pits in the stem
Epinasty
Stony pit
What is Betaflexiviridae Capillovirus?
apple stem grooving virus
What are symptoms of apple stem grooving virus?
This virus is usually symptomless
Where in the world can apple stem grooving virus be found?
worldwide
How does apple stem grooving virus spread?
Natural spread is Unknown
Mechanical inoculation is possible
What causes apple proliferation?
phytoplasma
How does apple proliferation spread?
Grafting
Leafhoppers
Is apple proliferation in the US?
No
Where in the world is apple proliferation?
Europe
How could apple proliferation enter the US?
budwood or tree smuggling into the US
Where in the plant is apple proliferation phytoplasma found?
only in the phloem
How is apple proliferation tranmitted?
Infected material
Grafting
Is apple proliferation quarantined?
Yes,
USA and Canada
What is a symptom of apple proliferation?
Witches broom
What percentage losses does apple proliferation cause?
10-80%
What symptoms does apple proliferation cause economically?
reduced fruit size, weight, and quality
Is apple proliferation spread through seeds?
No
What is a common symptom on the graft of apple proliferation?
black lines along the grafting point
What pathogen causes fire blight?
bacteria
Where on the plant does fire blight occur?
blossoms
shoots
limbs
What is Erwinia amylovora?
bacteria causing fire blight
Where did fire blight first occur?
North America
Where does fire blight overwinter?
in infected host plants only
What was the first bacterium shown to be a pathogen to plants?
Fire blight
What is Erwinia amylovora?
bacteria that causes fire blight
When was fire blight discovered?
1885
Were Japan’s quarantine on US apples due to fire blight justified?
No
Where does fire blight overwinter?
in cankers
What comes out of fire blight cankers?
bacterial ooze
When does bacterial ooze occur from fire blight?
several weeks prior to bloom
How is fire blight spread?
insects (mainly flies) during bloom
wind
rain
rootstocks
What are the symptoms of fire blight?
cankers
bacterial ooze
blossom blight
What is the main symptom of fire blight?
Shepherd’s crook
What control measures are used to control fire blight?
avoid susceptible cultivars good fertilization remove inoculum control insects well timed sprays growth regulators
What type of organism causes apple scab?
fungi
What direct losses are caused by apple scab?
fruit infections
What indirect losses are caused by apple scab?
tree defoliation
What is Venturia inaequalis?
The causal agent of apple scab
What is Spilocea pomi?
the causal agent of apple scab
Where do apple scab symptoms occur?
on the above ground parts of the apple tree
Where are apple scab legions first seen?
underside of expanding leaves
Where is the growth of apple scab limited to on living leaves?
between the cuticle and epidermis
What symptoms of apple scab occur on the fruit?
legions are brown and corky
uneven development of fruit (deformation)
cracks in the flesh of infected fruit
lesions on fruit
What is pinpoint scab?
apple scab that occurs on fruit in late summer infections
How does apple scab overwinter?
as pseudothecia (similar to sclerotia)
How many cycles of ascospore occur during one season with apple scab?
one
How can apple scab be controlled?
genetics
chemicals - preventative
cultural - sanitization, urea, tilling, pruning, no overhead irrigation
How many plants does cedar apple rust require to complete a life cycle?
two - cedar and apple
What is Gymnosporangium juniperi?
the causal agent of cedar apple rust
What two plants does cedar apple rust alternate between?
eastern red cedar and apple
Which one apple cultivar is nearly immune to cedar apple rust?
Delicious
What is the most profound symptom of cedar apple rust?
bright orange glistening lesions on leaves
what cedar apple rust spore producing structures occur on the lower leaf surface?
aecia
Where does cedar apple rust overwinter?
in galls on the cedar tree
What does wetting of the galls of cedar apple rust result in during the spring season?
spore horns
How long does it take for cedar apple rust legions to occur after infection?
10-14 days
How many seasons can one cedar apple rust gall produce spores?
only one season
Where do all of cedar apple rust lesions on the apple tree result from?
spores produced on a cedar tree
Does cedar apple rust produce secondary infections on apple trees?
No
How can we control cedar apple rust?
fungicide applications
remove cedars within a 2 mile radius interupts the life cycle
remove all cedars within 4-5 miles provides complete control
what pathogen causes southern blight?
Sclerotium rolfsii
what is sclerotium rolfsii?
the causal agent of southern blight (a fungi)
What age apple tree is most susceptible to southern blight?
1-3 year old trees
Where on an apple tree does southern blight symptoms occur?
lower stems and roots
What measures can be used to control southern blight?
avoid sites with previous disease
remove organic matter around base of the tree
What other crops does southern blight infect besides apple?
peanut
clover
tomato
soybean
What is currently the most resistant rootstock to southern blight?
M.9
What three forms does black rot occur in?
fruit rot
frogeye leaf spot
limb canker
What is Botryospaeria obtusa?
the causal agent of black rot
What is Physalospora obtusa?
the causal agent of black rot
What does black rot do to apple fruit?
causes apple mummies
What signs of black rot often occurs on apple fruit?
Black pycnidia
Where does black rot overwinter?
cankers
dead bark
mummified fruit
What are control measures for apple black rot?
remove dead wood, mummies, and cankers
fungicides
Where in the USA is apple bitter rot more important?
Southern states
What weather does apple bitter rot prefer?
warm wet weather
What are the primary hosts of apple bitter rot?
Apple
Pear
What is the causal agent of apple bitter rot?
Colletotrichum
When does apple bitter rot symptoms occur?
when fruit begins to mature
What type of pathogen causes apple bitter rot?
a fungi
What type of pathogen causes apple black rot?
a fungi
What fungal diseases occur on apples?
Apple Scab Cedar Apple Rust Southern Blight Black Rot Bitter Rot
What color spores occur with apple bitter rot?
pinkish
What shape is the rotten flesh of apple bitter rot?
V-shaped
Where does apple bitter rot overwinter?
mummified fruit, in bark, in cankers
What rot organisms can penetrate unbroken skin?
bitter rot
How many hours does apple bitter rot need to infect the plant?
5
How can apple bitter rot be controlled?
Fungicides
remove mumified fruit dead wood, twigs from trees
