Walt Stevenson

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Disease Problems and Solutions for Pea Growers
Walt Stevenson UW- Madison Department of Plant
Pathology
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Pea Diseases

• Fungal
• Anthracnose - Colletotrichum pisi
• Ascochyta Blight - Mycosphaerella pinodes
• Powdery Mildew - Erysiphe polygoni
• Root Rot - Aphanomyces euteiches
• Bacterial
• Bacterial Leaf Blight - Pseudomonas syringae
  pvar. pisi
• Virus
• Pea Mosaic

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Anthracnose
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Anthracnose
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Anthracnose
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AnthracnoseKey Points

• Pathogen Colletotrichum pisi
• Affects leaves, stems, pods
• Pathogen survives over winter in infected debris
  and on seed
• Spores are moved by splashing and wind-blown rain
• Frequent wind-blown rain, high humidity and warm
  temperatures favor disease

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AnthracnoseControl Strategies

• Use seed grown in the western U.S. - very low
  level of infestation
• Crop rotation - minimum 3 years

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Powdery Mildew
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Powdery MildewKey Points

• Pathogen Erysiphe polygoni
• Usually more important on late season crops
• Can cover entire aboveground plant, severely
  infected plants have poor yield and quality
• Infected pods off flavor
• Overwinters on infected plant debris, alternate
  hosts and seed
• Local and long distance spread by air currents
• Disease favored by absence of rain, presence of
  dew

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Powdery MildewControl Strategies

• Resistant cultivars
• Maestro
• Olympia
• Snappy
• Snowflake
• Sulfur spray or dust

• Sugar Bon
• Sugar Daddy
• Triplet

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Ascochyta Blight
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Ascochyta BlightKey Points

• Pathogen Mycosphaerella pinodes
• Affects leaves, stems, pods
• Pathogen survives over winter in infected debris
  and on seed
• Dispersal
• Asexual spores moved by splashing and
  wind-blown rain
• Ascospores carried by air currents
• Disease favored by high moisture, can occur over
  an range of temperatures

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Ascochyta BlightControl Strategies

• Use seed grown in the western U.S. - disease free
• Crop rotation - 3-4 year
• Prompt incorporation of crop residue after
  harvest
• Locate new pea fields at least 1/4 mile from old
  ones

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Aphanomyces Root Rot
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Aphanomyces Root Rot
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Aphanomyces Root Rot
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Aphanomyces Root RotKey Points

• Pathogen Aphanomyces euteiches
• The most important pea disease in the midwest and
  northeast U.S.
• Kills branch roots, leads to stunted weakened
  plants, premature death
• Overwinters in debris as oospores which can
  survive 20 years or more
• Dispersed by water and movement of infected plant
  debris or infested soil by farm machinery
• Favored by warm temperatures, high soil moisture
  can also occur at cool-moderate temperatures

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Aphanomyces Root RotControl Strategies

• Long rotations with non-legumes
• Select fields with well-drained soil
• Test soil for root rot potential
• Use good fertilization practices
• Trifluralin herbicide gives some protection

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Root Rot Potential
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Root Rot Potential

• 0 to 50 Safe to plant
• 51 to 69 Questionable safety
• 70 to 100 Dangerous, do not plant

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Fusarium Wilts
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Fusarium Wilts
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Fusarium WiltsKey Points

• Pathogen Fusarium oxysporum f. sp. pisi
• Causes loss of normal color, downward curling of
  leaves, eventual wilting of plant
• Pathogen lives indefinitely in soil (with or
  without pea debris)
• Dissemination
• Fungus moved by water, farm implements moving
  infested soil or infected vines
• Infected seed
• Optimum temperature for disease varies with race
  of fungus

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Fusarium WiltsControl Strategies

• Resistant cultivars
• Alaska
• Bounty
• Day Break
• Dual
• Frosty
• Green Arrow
• Knight
• Rotation

• Little Marvel
• Mars
• Novella
• Oregon Sugar Pod
• Sparkle
• Spring

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Bacterial Blight
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Bacterial Blight
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Bacterial BlightKey Points

• Pathogen Pseudomonas syringae pvar. pisi
• Affects all above portions of plant
• Pathogen overwinters in plant debris and in the
  seed coat
• Dispersal
• Local - splashing water
• Long distance - infected seed
• Cool overcast, wet weather, high humidity favor
  disease warm, dry conditions slow it

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Bacterial BlightControl Strategies

• Rotation with non-host crops (at least 3-year)
• Use disease free seed
• Avoid over-irrigation

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Pea Streak Mosaic
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Pea Streak Mosaic
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Pea Enation Mosaic Virus
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Pea Enation Mosaic Virus
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Pea Enation Mosaic Virus
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Pea Seed-Borne Mosaic
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Pea Seed-Borne Mosaic
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Pea MosaicKey Points

• Symptoms
• Most severe when early infection occurs
• Type and severity varies with virus strain
• Masked or greatly delayed below 60 F, develop
  typically in the 65-75 range

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Pea MosaicControl Strategies

• Aphid control
• Resistant varieties
• Early Snap BYMV
• Knight BYMV, PEMV
• Maestro BYMV, PEMV
• Oregon Giant PEMV
• Oregon Sugar Pod PEMV