Root Lesion Nematodes

• David Wichman’s samples

• In Oregon losses 8-60% (Semi-arid)

• Pratylenchus neglectus, P. thornei

• Species-specific resistance

Root Lesion Nematodes

Endoparasites

Root-lesion nematode damage to wheat

Cortical rot and pruning of lateral roots

Machete + aldicarb

27.8 bu/acre

Machete control

14.3 bu/acre

Annual No-till Spring Wheat in Soil Infested by P. thornei at Pendleton

Photo courtesy of Richard Smiley

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

Survey design148 fields in 2006 116 fields in 2007Alan Dyer and Wendy Johnson compared:

Tillage type Cropping intensity

Previous crop

Whitehead Tray

Method

Pratylenchus spp. kg dry soil

Counting

Soil moisture

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)

Mean populations relative to cropping systems

No

-T

ill

Co

nven

tio

nal

Recro

p

Fallo

w

SW

heat

WW

heat

0

500

1000

1500

2000

2500

3000

3500

4000

4500

Pratyle

nch

us n

eg

lectu

s/

kg

dry s

oil

Ranking of Root Lesion Nematode Populations

Resample in 2007

Survey Results

County x RLN RLN

Incidence

RLN Incidence above damage

threshold x Stunt

Stunt Incidence

Chouteau 3844 60% 30% 1036 90% Fergus 3375 100% 70% 2310 100%

Cascade 3252 80% 40% 667 90% McCone 1440 70% 20% 2485 100%

Hill 880 60% 10% 3005 100% Pondera 679 40% 10% 1410 100%

Toole 565 40% 10% 1860 100% Yellowstone 301 90% 0% 2311 100%

Glacier 89 20% 0% 2544 90% Phillips 73 50% 0% 420 90%

Roosevelt 61 10% 0% 1672 100% Valley 5 10% 0% 1460 90% Liberty 0 0% 0% 2970 100% Dawson 0 0% 0% 1900 100% Sheridan 0 0% 0% 202 28% Richland 0 0% 0% 303 100% Daniels 0 0% 0% 1895 100%

What Can You Do?What Can You Do?

• Avoid recrop (Tillage?)

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

Future Work• Repeat survey

• Develop resistance (Winter Wheat; Alan Dyer and Phil Bruckner)

• Seed treatment

Oregon and Washington yield losses up to 70% in

intolerant cultivars

(Smiley et al. 2005)

Oregon and Washington yield losses up to 36% in

intolerant cultivars

(Smiley et al. 2005)

Courtesy of Jason Sheedy

Pratylenchus thornei

Pratylenchus neglectus

Root Lesion Nematodes Damaging to WheatRoot Lesion Nematodes Damaging to Wheat

Good Hosts

Moderate Hosts Poor Hosts

Wheat

Canola

Mustard

Chickpea

Barley

Oat

Durum

Field Pea

Faba Bean

Lentil

Triticale

Safflower

Flax

Wide host range for P. neglectus

Migratory endoparasites

Anhydrobiosis

Wild Oat(Vanstone 2002)

Root Lesion Nematode Root Lesion Nematode BiologyBiology

Why didn’t we look before?

Infestations mimic and are exacerbated by fungal infestations, nutrient

deficiencies, and drought.

Courtesy of CBARC Research Station, Pendelton, OR

Department of Agriculture and Food Western Australia

Root Lesion NematodeRoot Lesion NematodeManagementManagement

1)Rotation non-host crop

2)Resistance varietal selection

• no chemical control

Survey design148 fields in 2006 116 fields in 2007Alan Dyer and Wendy Johnson compared:

Tillage type Cropping intensity

Previous crop

County x P.neglectusRLN 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

2006 Survey Results for Root Lesion Nematode

County x P.neglectusRLN 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

2007 Survey Results for Root Lesion Nematode

2006 Previous CropS

pri

ng

Wh

eat

Win

ter

Wh

eat

0

1000

2000

3000

4000

5000

6000

Pra

tyle

nch

us

neg

lect

us/

kg

so

il 2007 Previous Crop

Sp

rin

g W

hea

t

Win

ter

Wh

eat

0

1000

2000

3000

4000

5000

6000

Pra

tyle

nch

us

neg

lect

us/

kg

so

il

Root Lesion Nematodes

p=0.02p=0.15

Root Lesion Nematodes

2006 Tillage TypeN

o-t

ill

Co

nve

nti

on

al

0

1000

2000

3000

4000

5000

6000

Pra

tyle

nch

us

neg

lect

us/

kg

so

il 2007 Tillage Type

No

-Till

Co

nve

nti

on

al

0

1000

2000

3000

4000

5000

6000

Pra

tyle

nch

us

neg

lect

us/

kg

so

il

p=0.14 p=0.42

2006 Cropping IntensityA

nn

ual

Cro

p

Wh

eat

Fal

low

0

1000

2000

3000

4000

5000

6000

Pra

tyle

nch

us

neg

lect

us/

kg

so

il 2007 Cropping Intensity

An

nu

al C

rop

Wh

eat

Fal

low

0

1000

2000

3000

4000

5000

6000

Pra

tyle

nch

us

neg

lect

us/

kg

so

il

Root Lesion Nematodes

p=0.51 p=0.95

Survey conclusionsP. neglectus was found at damaging levels in the

north-central counties of MontanaSignificantly higher populations of P. neglectus

were found following a crop of winter wheatNo P. thornei was found…good for us!