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“[...] 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
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
Example of “struggling” vineyard with nematode problems
Courtesy of Dr. T Forge, photo taken by Dr. T Vrain
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
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300
350
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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
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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.
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