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