New Grape Grower Workshop

Nematodes in Vineyards John M. Halbrendt <jmh23@psu.edu>

Nematodes Compared to Pin Head

Nematodes - “The Unseen Enemy”

Nematode Pathogens on Grapevines

Lesion

Root Knot

Ring

Dagger

Others reported but pathogenicity has not

been proven e.g. Lance

Nematode Pathogens in the Mid-Atlantic region

Lesion - serious problem in some areas

Root Knot - problem in sandy soil

Ring - problem in sandy soil

Dagger - most important, virus vector, very

common

Ring nematode, Mesocriconema sp

Feeding damage by Lesion and Ring nematodes

Healthy

Check Damaged roots Feeding creates

wounds

for secondary infections

Poor Vine Establishment

Stunted Growth

Reduced Yield

Shortened Productive Life

Galls on 'Cabernet Sauvignon' caused by

Root-knot nematodes

Female root knot

nematode laying 500 eggs

every 35 days

The Tomato Ring Spot Virus is vectored by the

Dagger nematode (Xiphinema americanum)

The Dagger nematode:

• Very common in the mid-Atlantic region

• Has a broad host range

• Long lived nematode (up to 3 years)

• Weak parasite

• Efficient vector of ToRSV

Tomato Ringspot Virus on ‘Chardonnay’

Hen and chick symptom of ToRSV infection

Broadleaf Weeds – natural reservoir of ToRSV - at least 23 common

weeds are alternate hosts.

Also - ToRSV carried in weed seed and can be graft transmitted 10

Virus Transmission

The virus is transmitted from infected weeds to vines by dagger nematodes 11

DON’T INTRODUCE PROBLEMS

Distribution of ToRSV through propagation

"T" type sampling tools ideal for

collecting most soil samples. When sampling collect cores in a

zig-zag pattern across the site.

*Keep samples cool/from heat and sunlight

Combine 20 subsamples to

make one sample for testing.

A soil sample should not

represent more than 3 - 4 acres

Sampling for Nematodes

Once a nematode problem

develops it is difficult to

correct.

Good nematode management

in vineyards requires

preventive measures.

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Chemical control:

• Soil Fumigation

• Contact Nematicides

• Herbicides (virus control)

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Biofumigation The control of soil-borne diseases by the release

of isothiocyanates from plant tissues.

Biofumigation Chopped and Tilled Rapeseed (Green Manure)

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A thick stand of rapeseed can suppress weeds

Rapeseed can provide other benefits

Rapeseed makes a good winter ground cover

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Photo by Dr. R. Weil

Soil Horizons

A

B

C

The rapeseed taproot can penetrate deep and loosen compacted soil

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Questions?