soil nematode survey associated with vegetable in vermont meeting 2009/soil...soil nematode survey...
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Soil Nematode Survey
Associated with Vegetable in Vermont
Bao Yong
Dept. Plant and Soil Science
The University of Vermont
Where I came from
My Hometown Landscapes
The lower reaches of the Yangze River
Highly populated
Colorado potato beetle
Squash bugs
Cabbage worm
Cutworm
Aphids
Cucumber beetle
Nematodes
Common “Local Vegetarian” in Vermont
What are Nematodes?
• Aquatic
• Transparent
• 0.40 -1.0 mm in length
• Bilaterally symmetrical– longitudinal muscles only
• Vermiform roundworms
• Typically bisexual– dioecious, internal
fertilizationFigure 1. Entire body view of a female Pratylenchus agilis (100x magnification) collected on the Konza Prairie (96W35’ 39N05’) beneath Scribner’s Panicum (Panicum scribnerianum)/bluegrass (Poa pratensis) near Manhattan, Kansas. Photograph is provided courtesy of Peter Mullin/2000.
Nematode Nema: Thread Tode: form(Greek)
Where do they live ?
Nematodes Infestation and Soil Texture
0
5
10
15
20
25
Sand Loam Cl ay Rock
Lesion# per plant
Uneven and patchy
distribution within
and between fields
Variability at depth
Seasonal fluctuations
Sensitive to their
environment
Nematode Soil Distribution 101
How many are they?
Trophic Groups in Nematode Community
Most important nematodes on vegetables
in the Northeast
Northern root-knot Meloidogyne hapla
Root-lesion Pratylenchus penetrans
Cyst nematodes Heterodera schachtii
Globodera rostochiensis
Abawi G. Cornell Extension
Pest Management History?
Cropping History ?
Organic Matter Input?
Cover Crops?
Chemicals Applications?
Crop rotation options?
Soil Bioassay for Lesion Nematode with Soybean
Field soil is planted with
soybean seed
Soil collection
Plants grown in a growth
chamber for 2 to 3
weeks
Roots are washed under
running tap water
Lesion severity is assessed based
on the number of lesions on the
main taproot
Soil Bioassay for Root-Knot Nematode with Lettuce
Soil collectionLettuce grown in greenhouse
5 to 6 weeks
Root galling severity rating
(1 = healthy to 9 = severely galled) Lettuce roots are washed
2 lettuce seedlings
planted in field soil
It Works!
R2 = 0. 7644
0
300
600
900
0 6 12 18 24 30Root Lesi ons ( # per pl ant )
Lesion Nematodes Abundance
(individuals/100cc soil)
Grower employee
setting-up the
nematode bioassays
in the back of a van.
Evaluation of the
nematode bioassays
with the grower.
And you can do it by yourself on your farm
In Vermont associated with Vegetable
20 families 39 genus
1585 individuals per 100 cc soil
Frequency of Plant-parasitic Nematodes
associated with Vegetables in Vermont
Pratylenchus ---- Lesion Nematode
Head Male Tail Female Tail
# 1 Killer
Lifecycle of Lesion Nematode
From Agrios, 1997
Seasonal fluctuations of root lesion nematode
population in soil planted with susceptible crop
In bulk soil
In roots
Spring Summer Fall Winter
Nem
ato
de d
en
sit
y
Abundance of Lesion Nematodes associated with
Vegetable in Vermont
0
50
100
150
200
250
Spr i ng Fal l
Lesion Nematode Abundance
(individuals/100cc soil)
Hosts for Lesion Nematodes
Over 550 species of plants including large
numbers of agronomic crops and weed species
Lesions on soybean root
Root-lesion nematode (Pratylenchus penetrans)
in an onion root
eggs
juveniles
Disruption of water and nutrient up-take
General field symptoms include
Reduced growth
Yellowing of foliage (nutrient deficiency-like)
Excessive wilting in hot or dry weather
Reduced yields
Poor quality produce Symptom severity
are nematode
density dependent.
Healthy lettuce plants
Stunted and uneven growth due to nematode infection
Tactics/Options
Cultural and soil management
practices:
Crop rotation
Cover crops
Organic manuring
Sanitation and crop
nutrition
Incorporation of cover crops as
green manures against Pratylenchus
penetrans.
0 250 500 750 1000 1250 1500 1750 2000
Hairy Vetch
Alfalfa
White clover
Rye grain
Alsike clover
Phacelia
Radish
Crown vetch
Red clover
Wheat
Oats
Buckwheat
Mustard
Ryegrass
Rapeseed
Sudex
Number of lesion nematodes/ g bean root
Cover crops suppressive effect on lesion nematodes in Vermont
0
2
4
6
NO YES
In(Lesion Nematode Abundance)
(individuals/100cc soil)
Cl over
Sudangr ass
b
a
Animal Manure’s suppressive effect on plant-parasitic nematodes in Vermont
0
0. 1
0. 2
0. 3
0. 4
N Y
Percentage of Plant-parasitic nematode %
b
a
Barker, K.R. and Olthof, T.H.A. 1976. Relationship between nematode population
densities and crop responses. Annu. Rev. Phytopathology 14:327-353.
Average Lesion Nematode abundance
associated with vegetables is as high as
224 individuals per 100cc soil in Vermont
Take Home Message
Soil Biological Indicators LabDr. Deborah Neher uses soil nematode & microarthropods for
monitoring soil quality (Telephone:802-656-0474 http://www.uvm.edu/~dneher/)
-1.0 +1.0
-1.0
+1.0
cellulose
EC
cellulose/lignin
organic carbon
moisture
pH
pyrene
phenanthrene
fluoranthene
5-ring
clay
benzo[a]pyrene
sand
bulk density
HymenopteraL
Symphyla
Pauropoda
Onychiuridae
other mites
fungi
Oribatida
proturans
HymenopteraA
bacteria
DiplopodaL
Isotomidae
Homoptera