Root Lesion Nematodes

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Root Lesion Nematodes

• David Wichmans samples
• In Oregon losses 8-60 (Semi-arid)
• Pratylenchus neglectus, P. thornei
• Species-specific resistance

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Root Lesion Nematodes
Endoparasites
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Root-lesion nematode damage to wheat
Cortical rot and pruning of lateral roots
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Annual No-till Spring Wheat in Soil Infested by
P. thornei at Pendleton
Machete aldicarb 27.8 bu/acre
Machete control 14.3 bu/acre
Photo courtesy of Richard Smiley
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The Spring Survey (2006)

• 10 poorly performing fields in each of the 17 top
  wheat producing counties
• Extension Agents
• Information about cropping systems?

Wendy Lewis
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Survey design

• 148 fields in 2006
• 116 fields in 2007
• Alan Dyer and Wendy Johnson compared
• Tillage type
• Cropping intensity
• Previous crop

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Whitehead Tray Method
Soil moisture
Pratylenchus spp. kg dry soil
Counting
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Survey Results

• 148 fields were examined in 17 counties
• Pratylenchus neglectus found in 12 counties
• P. thornei was never found (important!)
• 14 of the fields had populations which exceeded
  damage thresholds (2500 nematodes/kg of soil)

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Mean populations relative to cropping systems
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Ranking of Root Lesion Nematode Populations
Resample in 2007
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Survey Results
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What Can You Do?

• Avoid recrop (Tillage?)
• Rotate to field peas? (Tailor et al. 2000)

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Future Work

• Repeat survey
• Develop resistance (Winter Wheat Alan Dyer and
  Phil Bruckner)
• Seed treatment

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Root Lesion Nematodes Damaging to Wheat
Pratylenchus thornei
Pratylenchus neglectus
Courtesy of Jason Sheedy
Oregon and Washington yield losses up to 36 in
intolerant cultivars (Smiley et al. 2005)
Oregon and Washington yield losses up to 70 in
intolerant cultivars (Smiley et al. 2005)
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Root Lesion Nematode Biology
Good Hosts
Moderate Hosts
Poor Hosts
Field Pea Faba Bean Lentil Triticale Safflower Fla
x
Wheat Canola Mustard Chickpea
Barley Oat Durum
Wide host range for P. neglectus
Wild Oat (Vanstone 2002)
Anhydrobiosis
Migratory endoparasites
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Why didnt we look before?

• Infestations mimic and are exacerbated by fungal
  infestations, nutrient deficiencies, and drought.

Department of Agriculture and Food Western
Australia
Courtesy of CBARC Research Station, Pendelton, OR
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• Root Lesion Nematode
• Management
• 1)Rotation
• non-host crop
• 2)Resistance
• varietal selection

• no chemical control

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Survey design

• 148 fields in 2006
• 116 fields in 2007
• Alan Dyer and Wendy Johnson compared
• Tillage type
• Cropping intensity
• Previous crop

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County x P.neglectus RLN Incidence above damage threshold
Chouteau 3844 30
Fergus 3375 70
Cascade 3252 40
McCone 1440 20
Hill 880 10
Pondera 679 10
Toole 565 10
Yellowstone 301 0
Glacier 89 0
Phillips 73 0
Roosevelt 61 0
Valley 5 0
Liberty 0 0
Dawson 0 0
Sheridan 0 0
Richland 0 0
Daniels 0 0
2006 Survey Results for Root Lesion Nematode
2500 P. neglectus kg dry soil
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2006 Survey Results for Root Lesion Nematode
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County x P.neglectus RLN Incidence above damage threshold
Chouteau 3306 40
Cascade 2670 50
Fergus 2400 20
McCone 1285 10
Hill 953 10
Pondera 811 18
Toole 2375 10
Glacier 100 20
Phillips 0 0
Roosevelt 24 0
Valley 29 0
Liberty 385 10
Sheridan 0 0
Daniels 0 0
2007 Survey Results for Root Lesion Nematode
2500 P. neglectus kg dry soil
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2007 Survey Results for Root Lesion Nematode
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Root Lesion Nematodes
p0.15
p0.02
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Root Lesion Nematodes
p0.14
p0.42
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Root Lesion Nematodes
p0.51
p0.95
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Survey conclusions

• P. neglectus was found at damaging levels in the
  north-central counties of Montana
• Significantly higher populations of P. neglectus
  were found following a crop of winter wheat
• No P. thornei was foundgood for us!