“[...] if all the matter in the universe except

the nematodes were swept away, our

world would still be dimly recognizable,

and if, as disembodied spirits, we could

then investigate it, we should find its

mountains, hills, vales, rivers, lakes, and

oceans represented by a film of

nematodes…”

~ N. A. Cobb, 1914

Soil Nematodes

Rosy Smit M.Sc. Soil Science (UBC)

Overview

Nematode 101

Management practices and control

Example of current local research to enhance free-living and control plant parasitic species

Summary Resources

Nematode 101

• Microscopic, un-segmented roundworms

• Most abundant multi-cellular life forms on earth (10 to 100 K/L soil) – Most are < 1 mm long

– Occupy soil, aquatic sediments, plants, animals

– Diverse (>25,000 species)

• Free living and plant parasitic

• Plant parasites can cause severe crop losses and damage

• Occupy all trophic levels of the soil food web

Free-living nematodes

Fungivores

Bacterivores

Predators

Omnivores

http://soils.usda.gov/SQI/concepts/soil_biology/nematodes.html

Plant parasitic nematodes - see the stylet

Courtesy of Dr. T Forge

Dagger nematode feeding on root tip

Courtesy of Dr. T Forge

Example of “struggling” vineyard with nematode problems

Courtesy of Dr. T Forge, photo taken by Dr. T Vrain

Dagger nematodes damage on Grape roots

Healthy Damaged

Root Lesion nematode damage on Corn roots

http://www.plantpath.wisc.edu/PDDCEducation/ScoutSchool/General/Slide66.htm

Root knot nematode damage on Lettuce and

Carrot

http://www.apsnet.org/online/Archive/PDCoverImages/2004v88/jan_1.jpg

http://www.umassvegetable.org/images/soils_crops_pest_mgt/disease/carrot_root_knot.jpg

Plant parasitic nematode management

Short-term “management” • Chemical

– Nematicides

• Solarization • Nematicidal cover crops and

green manures • Biofumigation

– Brassicas, Marigolds

Long-term “management” • Cultural practices

– Resistant/tolerant rootstock varieties?

– Compost application?

Courtesy of Dr. T Forge

Compost application and its effects on soil and nematode populations

• Increased soil health

– Enhanced soil chemical and physical properties

• Enrichment of opportunistic species, enhanced species indicative of diversity and structure

• What would the effect of compost be on plant parasitic nematodes?

In-vineyard compost trials

• Trials set up in 2005 by Dr. Gerry Neilsen from PARC-Summerland

• Treatments = different application rates of chemical fertilizer and compost

• Compare nematode populations as influenced by compost or chemical fertilizer applications

• Compost surface-applied to each plot at a rate to give approximately 40 kg N/ha

• Conventional fertilizer applied at 40 kg N/ha

Data collection

• Soil cores taken four times

(Fall 2007, Spring Summer and Fall 2008)

• Free-living nematodes extracted, identified to genus and counted

• Plant parasites identified

and counted

Plant parasitic nematodes found…

Courtesy of Dr. T Forge

Root Lesion nematode Pratylenchus sp.

• Found in many vineyards in South Okanagan

• Found with other plant parasitic species

• Cosmopolitan plant parasite has wide host range

Courtesy of Dr. T Forge

Ring nematode Mesocriconema sp.

• Overlooked in the Okanagan until 2004

• Extraction methods inefficient for this species

• Found with other plant parasitic species

• Can increase to high populations in sandy soils

• Pathogenicity of Okanagan sp. unknown

Soils in the compost trials

• Originated from Glacial lake deposits

• All trials had very coarse textured sandy soil

• Very well drained

• Very low organic matter

• Very low nutrient and water retention

Courtesy of Burrowing Owl Vineyard

Mean values of bacterivorous nematodes under compost and fertilizer treatments for four sample dates.

a

a

a

a

a

aa

b

0

50

100

150

200

250

300

350

400

450

500

Fall 2007 Spring 2008 Summer 2008 Fall 2008

avera

ge n

um

ber

of

nem

as p

er

100g

/so

il

Compost

Fertilizer

Mean values of fungivorous nematodes under compost and fertilizer treatments for four sample dates.

a

a

a

a

a

a

bb

0

10

20

30

40

50

60

70

80

90

100

Fall 2007 Spring 2008 Summer 2008 Fall 2008

avera

ge n

um

ber

of

nem

as p

er

100g

/so

il

Compost

Fertilizer

Mean values of omnivorous and predacious nematodes under compost and fertilizer treatments

for four sample dates.

a

a

a

a

a

a

a

b

0

10

20

30

40

50

60

70

80

90

100

Fall 2007 Spring 2008 Summer 2008 Fall 2008

mean

nu

mb

er

of

om

niv

ore

an

d p

red

ato

r

nem

ato

de s

pecie

s p

er

100g

/so

il

Compost

Fertilizer

Mean Pratylenchus spp. counts for both Tennant’s and Bullpine vineyard sites for four sample dates

under compost and fertilizer treatments.

0

5

10

15

20

25

30

35

40

fall 07 spring 08 summer 08 fall 08

mean rin

g n

em

ato

de c

ount /1

00g s

oil

Bullpine compostBullpine fertilizerTennant's compostTennant's fertilizer

Mean M. xenoplax counts for both Tennant’s and Bullpine vineyard sites for four sample dates

under compost and fertilizer treatments.

0

20

40

60

80

100

120

140

fall 07 spring 08 summer 08 fall 08

me

an

rin

g n

em

ato

de

co

un

t /1

00

g s

oil

Bullpine compost

Bullpine fertilizer

Tennant's compost

Tennant's fertilizer

Results

• Soil food web enrichment

Compost increased

• nematode indicators of soil food web enrichment (bacterivores, fungivores)

• nematode indicators of soil food web diversity (omnivores and predators)

but the effect was not long lasting.

• Plant parasitic nematodes

– M. xenoplax and Pratylenchus spp. nematode populations increased in compost amended plots.

Rootstock Microplot trial

Use of rootstocks

• Little is known as to resistance/tolerance of grape rootstocks to Okanagan nematodes

• Research project to compare the performance, resistance or tolerance from 3 selected rootstocks and self-rooted Merlot vines to 2 species of local parasitic nematodes and also combined inoculations

* Rootstocks include Riparia Gloire, 3309C, 44-53M and self-rooted Merlot

Rootstock trial set-up and data collection

• Located at PARC- Summerland • Self-rooted Merlot vines and the

rootstocks planted into 160 – 100 L pots (after fumigation)

• Soil samples twice a year, prune weights and stem diameters yearly

• Treatments – ten pots of each plant type were

inoculated with • M. xenoplax • Pratylenchus spp. • both nematodes • nothing

Mean 2009 pruning weights for three rootstocks and self-

rooted vines inoculated with or without M. xenoplax.

A

A

A

A

B

A

A

A

0

10

20

30

40

50

60

70

44-53M Riparia Gloire 3309C Self-rooted

pru

ne

we

igh

t (g

of

drie

d p

lan

t m

ate

ria

l)

ring nematode

no nematode

Results

• Self-rooted vines showed decline in growth under influence of M. xenoplax after two seasons of growth

• No significant differences in growth of rootstocks

• Other results are forthcoming as the rootstock trial is ongoing…

Other exciting nematode research…

Dr. Tom Forge at PARC-Agassiz

• Impacts of plant-parasitic nematodes on root dynamics and productivity of wine grapes in the Okanagan Valley

• Role of plant-parasitic nematodes in root decline of blueberry

Summary

Soil nematodes are important in agriculture!

• Out of sight, but not out of mind!

• Look at the root systems if plants are unthrifty or unexplained reductions in yield

• Enhance your soil biological system with additions of organic matter

• Use a variety of soil management methods to increase soil health (rotation, cover crops, reduced tillage if possible)

Nematode Testing in B.C.

Soil analysis for nematodes is provided for a fee by:

Plant Diagnostic Lab Ministry of Agriculture and Lands

Abbotsford Agriculture Centre, 1767 Angus Campbell Road, Abbotsford B.C., V3G 2M3 Tel: 604 556-3126 (directly) or 1-800-661-9903 (main office) Fax: 604 556-3154

Resources

Basic soil nematode information

http://www.extension.org/article/24726

http://www.entnemdept.ufl.edu/creatures/nematode/soil_nematode.htm

http://www.apsnet.org/online/feature/nematode/

OMFRA - Sampling Soil and Roots for Plant Parasitic Nematodes

http://www.omafra.gov.on.ca/english/crops/facts/06-099.htm

BCMAL Plant Diagnostic Lab ** form and address/phone number

http://www.al.gov.bc.ca/cropprot/lab.htm

Soil nematode management and plant parasitic control practices

http://attra.ncat.org/attra-pub/nematode.html

Thank you for your attention! Questions?

http://www.apsnet.org/education/k-12plantpathways/teachersguide/Activities/ Nematode/exercisepg1.htm