Asparagus Diseases

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Asparagus Diseases

• Fusarium Wilt / Root Rot / Decline - Fusarium
  oxysporum, Fusarium moniliforme
• Rust - Puccinia asparagi

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Asparagus Rust (aecial stage)
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Asparagus Rust (uridinial stage)
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Asparagus Rust (telial stage)
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Asparagus Diseases - RustKey Points

• Pathogen Fungus Puccinia asparagi
• Symptoms confined to ferns
• Symptoms include red/brown/black elongated spots
• Ferns yellow and plants are weakened
• Fungus passes through all four stages on
  asparagus
• Fungus overwinters on old stems and stubble
• Infection favored by heavy dews
• Spores spread by wind and splashing rain

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Asparagus Diseases RustControl Strategies

• Several rust-resistant cultivars
• Jersey Knight hybrid
• Mary Washington
• Viking KB3
• Orient planting parallel to prevailing winds to
  promote air circulation and drying
• Fungicides are helpful when applied to growing
  ferns after harvest

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Asparagus Diseases Fusarium Wilt
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Asparagus Diseases Fusarium Wilt
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Asparagus Diseases Fusarium Wilt
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Asparagus DiseasesFusarium Wilt/Root
Rot/DeclineKey Points

• Pathogen Fungi
• Fusarium oxysporum
• Fusarium moniliforme
• Symptoms include
• Premature yellowing of ferns
• Red-brown vascular discoloration
• Red-brown elliptical lesions on storage roots
• Internal discoloration of crowns
• Disease affects crown vigor, number of shoot
  buds, fern vigor and yield
• Most severe when plantings stressed by
• Moisture
• Extended harvest interval
• Low pH
• High nitrogen
• Disease reduces field longevity

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Asparagus DiseasesFusarium Wilt/Root
Rot/DeclineControl Strategies

• Minimize plant stress
• Adjust soil pH to 6.5 7.5
• Avoid overfertilization with N
• Plant in well drained soils and irrigate when
  needed
• Plant disease-free crowns
• Plant disease-resistant cultivars
• Jersey Knight Hybrid
• Viking KB3

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Beet Diseases

• Cercospora Leaf Spot - Cercospora beticola

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Cercospora Leaf Spot
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Cercospora Leaf Spot
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Beet Diseases - Cercospora Leaf Spot Key Points

• Pathogen Fungus Cercospora beticola
• Symptoms include brown to gray spots with
  distinct reddish-purple borders
• Fungus overwinters in residue from diseased
  plants 12-18 months
• Fungus can be seed-borne
• Spread by splashing water, insects, equipment
• Favored by high relative humidity and warm
  temperatures

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Beet Diseases Cercospora Leaf SpotControl
Strategies

• Fall plowdown of crop debris
• Crop rotation of 3 years
• Balanced fertility of N, P, K, B, and Na
• Fixed copper sprays may reduce severity
• Varieties with resistance or tolerance
• Big Red
• Red Ace

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Lettuce Diseases

• Bottom Rot - Rhizoctonia solani
• Drop - Sclerotinia sclerotiorum
• Downy Mildew - Bremia lactucae

• Aster Yellows

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Lettuce Diseases - Rust
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Lettuce Diseases Bottom Rot
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Lettuce Diseases Bottom Rot
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Lettuce Diseases Bottom RotKey Points

• Pathogens Fungi
• Bottom Rot Rhizoctonia solani
• Drop Sclerotinia sclerotiorum
• Both fungi produce sclerotia and are soil-borne
• Rhizoctonia thin, brown sclerotia
• Sclerotinia thick, black sclerotia
• Broad host range for both fungi
• Infection most likely on leaves covering soil
• Disease favored by wet weather
• Infected tissues become wet and slimy
• Both diseases can be very destructive

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Lettuce Diseases Bottom RotControl Strategies

• Crop rotation of 3 years minimum
• Plant on well-drained soils
• Plant on raised beds to improve air circulation
  and water drainage
• Directed fungicide sprays iprodione
  vinclozolin
• Resistance to bottom rot
• Carmona
• Dapple
• Nancy

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Lettuce Diseases Downy Mildew
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Lettuce Diseases - Downy Mildew
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Lettuce Diseases Downy MildewKey Points

• Pathogen Fungus Bremia lactucae
• Symptoms include yellowish or light green blotchy
  areas on leaves
• White downy mold on undersides of leaves
• Affected leaf areas die
• Favored by cool temperatures and high relative
  humidity
• Spores spread by wind

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Lettuce Diseases Downy MildewControl Strategies

• Plant in well-drained soils
• Careful spacing of plants improves air
  circulation
• Plant on raised beds to improve air circulation
  and water drainage
• Resistant varieties
• Nancy
• Salad Bibb
• Tania
• Titania

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Lettuce Diseases Aster Yellows
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Lettuce Diseases Aster Yellows
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Lettuce Diseases Aster Yellows
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Aster Yellows Index

• infectivity X leafhoppers/100 sweeps
• Crop Threshold
• Carrots
• Resistant 100
• Intermediate 75
• Susceptible 50
• Onion 50
• Celery 35
• Lettuce 25

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Lettuce Diseases Aster YellowsKey Points

• Pathogen Aster Yellows phytoplasma
• Wide host range at least 300 species in 48
  families. Vegetable hosts include carrot,
  endive, escarole, lettuce, and celery
• Leafhopper transmitted
• Symptoms include yellowing distortion of leaves
  and bitter taste
• Overwintering
• Perennial weeds and ornamentals
• Insect vector on grasses or grain crops
• Leafhopper vectors carried from southern US north
  by wind

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Lettuce Diseases Aster YellowsControl
Strategies

• Eradicate overwintering weeds and ornamental
  plants
• Do not plant adjacent to earlier plantings that
  were diseased
• Plant lettuce as far as possible from grain and
  grass crops
• Regular insecticide program to reduce leafhopper
  population
• No resistant or immune varieties

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Spinach Diseases

• Blue Mold (Downy Mildew) - Peronospora effusa

• Blight / Yellows - Cucumber Mosaic Virus

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Spinach Diseases Downy Mildew
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Spinach Diseases Downy Mildew
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Spinach Diseases Downy MildewKey Points

• Pathogen Fungus Peronospora effusa
• Symptoms include indefinite yellowish areas on
  leaf and gray to violet mold on corresponding
  lower leaf surface
• Fungus survives in seed and as oospores in soil
• Free water needed for infection
• Favored by cool, wet weather

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Spinach Diseases Downy MildewControl Strategies
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Spinach Diseases Spinach Blight/Yellows/CMV
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Spinach Diseases Spinach Blight/Yellows/CMV
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Spinach Diseases Spinach Blight/Yellows/CMV
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Spinach Diseases Spinach Blight/Yellows/CMVKey
Points

• Pathogen Cucumber Mosaic Virus
• Symptoms include mottling of young leaves
  followed by yellowing
• Foliage curls and wrinkles. Leaves may
  eventually die
• Symptoms progress rapidly at 82 degrees F
• Virus spread by aphids

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Spinach Diseases Spinach Blight/Yellows/CMVCon
trol Strategies

• Early spring crops escape infection
• Control perennial weed hosts
• Control aphid vectors
• Cultivars with resistance to CMV
• Melody Hybrid
• Winter Bloomsdale

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Spinach Diseases Pythium Damping-off
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Spinach Diseases Damping-off Soil-borne
Pathogens
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Spinach Soilborne FungiKey Points
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Spinach Soilborne FungiControl Strategies

• Seed treatment with currently registered
  fungicides.
• Do not plant spinach two years in succession in
  the same field or area.