ΝΗΜΑΤΟΔΕΙΣ-NEMATODES

7/29/2019 -NEMATODES

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Rootstocks for Nematode Management

Peter Cousins, Grape Rootstock Breeder and Geneticist, USDA ARS

New York State Agricultural Experiment Station, Cornell University

630 W. North Street, Geneva, NY 14456

315-787-2340 [email protected]

The goal of this presentation is to outline the use of rootstocks in managing nematodes in

vineyards. We will discuss the damage caused by nematodes, the value of using rootstocks

in managing nematodes, and considerations to make when choosing rootstocks and using

them in your vineyard.

This opening slide is of a cluster of wine grapeswhy? This is to remind us that rootstocks

are neither interesting nor important on their own. We use rootstocks in order to help us

produce quality fruitin this case, wine grapeswhile managing pests and diseases that

live in the soil and could damage grape roots. Rootstocks are one of the tools that we can

apply to the economically and environmentally sustainable production of fruit.


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Team Rootstock:

Targeting nematodes to make

America safe for viticulture

Debra Johnston

Jason Plate


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Acknowledgements

Washington Association of Wine Grape Growers

New York Wine and Grape Foundation

Viticulture Consortium

Cornell University and NYSAES

USDA-ARS

American Vineyard Foundation

California Raisin Marketing Board

California Table Grape Commission

California Grape Rootstock Research Foundation University of California


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In viticulture we use rootstocks to provide protection against pests and diseases ofthe soil. In other fruit crops, such as peach and apple, rootstocks are a requirementfor clonal propagation, since these trees are difficult to root from cuttings.However, most grape varieties are easily propagated from cuttings, so we userootstocks that provide protection (resistance or tolerance) against pests and diseases

that could damage the grapevine roots.

Phylloxera is the chief reason to use rootstocks in viticulturephylloxera feedingon roots can kill grapevines, which is usually not true of nematode feeding damage.Phylloxera are small insects, similar to aphids, that can feed on grapevine leaves androots. It is the root feeding that is the more damaging. Phylloxera is native toeastern North America (not to Washington). The grapevine species that are nativeto the original range of phylloxera are either resistant or tolerant to phylloxerafeeding. These species include Vitis riparia, Vitis rupestris, and Vitis berlandieri.Vitis vinifera, which is native to Europe and Asia, outside the original range ofphylloxera, is highly susceptible to the damage caused by phylloxera root feeding.When phylloxera was accidentally introduced to Europe in the 19th century, it spreadrapidly and many thousands of acres of vineyards were destroyed. Using rootstocksdeveloped from North American species was adopted as a sustainable practice forphylloxera protection, since these species co-exist with phylloxera. Because of theimportance ofV. vinifera varieties (such as Cabernet Sauvignon and Merlot) and thepotential for serious damange to V. vinifera vineyards from phylloxera, mostrootstock use and research takes place in the context of phylloxera resistance first,nematode resistance second, although there are a few exceptions.


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Nematode infested vineyard

Here is a nematode infested vineyard showing the damage to the vines caused by

nematode feeding. Note the smaller vines, demonstrative of root damage and

reduction in the ability of vines to take up water and nutrients. The roots are being

fed upon and damaged by root-knot nematodes (Meloidogyne species).

If nematodes are feeding on the roots of a grapevine, the symptoms on the shoot can

include water deficit stress (wilting), nutrient deficiency, stunting of shoots, and

decreased yield. It is unusual for vines to rapidly decline and die from nematode

feeding alone. However, in some cases young vines newly planted into a site with

very high nematode populations in the soil may fail to establish.


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Root-knot nematode galls on grapevine roots

Root system of susceptible grapevine after 8 weeks exposure to root-knot nematodes.

Root-knot nematodes (Meloidogyne species) are endoparasitic nematodes. The juvenile

nematode moves through the soil and burrows into the grapevine root, then moves through

the root, finally establishing a feeding site. The root-knot nematode swells up and becomesimmobile, feeding from the grapevine root cells through a hollow mouthpart called a stylet.

Susceptible grape roots usually respond to the nematode infection by galling and swelling,

creating the namesake root-knot. The galling and swelling of the roots reduces the ability of

the roots to take up water and nutrients. Harmful bacteria, fungi, and other organisms may

enter the grapevine root through the nematode entry wound and through the cracks that form

around the galls.

Many root-knot nematode species have a broad host range. They feed on and damage grape

as well as many other plants, including both crops and weed species. Management of root-

knot nematodes through crop rotation may be challenging due to the many species of plantsthat are suitable hosts, including alfalfa, common bean, tomato, peach, and watermelon.


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Close up of root-knot nematode infected grapevine root, with stained egg masseseach egg

mass can have 2000 eggs. In this picture, the nematode egg masses are red. Several of the

root-knot nematode species that are important on grapevine lay fertile eggs without mating

and can complete their life cycle in as few as 27 days. This demonstrates the enormous

potential for nematode populations to increase very rapidly.


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0.1 mmcourtesy of Marc Fuchs

The dagger nematodeXiphinema index is the vector of grapevine fanleaf virus,

which causes the disease fanleaf degeneration. Xiphinema index is a fairly large

nematode which can cause serious damage to grapevine roots on its own (even if it

is not vectoring the virus).

Xiphinema index is an ectoparasitic nematode, meaning that it feeds from outside

the grapevine root. It moves through the soil from grapevine to grapevine, making it

an effective vector for grapevine fanleaf virus. Xiphinema index does not have a

broad host range; it feeds on grapevine, olive, fig, and a few other plants, but most

plant species are not suitable hosts (in contrast to the broad host range of root-knot

nematodes,Meloidogyne species).


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Fruit cluster symptoms of fanleaf degeneration, caused by grapevine fanleaf virus.

On the left, a cluster from a healthy vine. On the right, a cluster from a vine

infected with grapevine fanleaf virus and showing the characteristic decline in berry

set associated with fanleaf degeneration disease. Infected vines may show an 80%

declinein crop. The grapevine fanleaf virus infects grapevines, but is not naturally

found in other crop plants or weeds. The reservoir for the virus is in grapevines, sousing virus tested grapevine planting material is recommended.

Grapevine fanleaf virus is spread byXiphinema index dagger nematodes. There are

rootstocks that provide protection against theXiphinema index dagger nematode, so

if the nematodes are not carrying the virus, these rootstocks could be suitable.

However, resistance to the nematode alone is not sufficient to provide protection

against fanleaf degeneration disease. This is because merely the probing of the

nematode with its stylet on the grapevine root is sufficient to transmit grapevine

fanleaf virus.

Presently the only rootstock recommended for protection against bothXiphinema

index dagger nematodes and fanleaf degeneration is VR O39-16.


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The shoot on the left is from a vine with ringspot decline caused by tomato ringspot

virus. The shoot on the right is from a healthy grapevine.

Ringspot declines of grapevine are caused by tobacco ringspot virus and tomato

ringspot virus. These viruses are spread byXiphinema americanum and closelyrelated dagger nematode species. The nematodes are ectoparastic (feeding from

outside the grapevine root) and just like theXiphinema index dagger nematode, they

move from plant to plant through the soil. In contrast toXiphinema index,

Xiphinema americanum nematodes have a broad host range and feed on many crops

and weed species in addition to grapevine. The ringspot viruses also have a broad

host range and can be transmitted from other crop plants or weeds to grapevine.

Management of ringspot declines andXiphinema americanum nematodes with

rootstocks is not well understood; one study showed that the rootstock 3309C

provided protection against infection by tomato ringspot virus while own-rootedvines were infected.


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Ringspot decline fruit symptoms. Clusters from healthy vines on the left and from

vines with ringspot decline on the right.


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A rootstock trial in a root-knot nematode infected vineyard near Fresno shows the value of

nematode resistance in rootstocks. The healthy, vigorous vines on either side are grafted o

nematode resistant rootstocks, while the weak and missing positions are grafted on

susceptible rootstocks. At this location root-knot nematodes are the chief soil pest, as

phylloxera is not an issue at this location.


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The vineyard pictured above has a vigor problemshoots are growing throughout

the season and even the trellis is obscured. When using rootstocks, the rootstock

and scion variety should be matched to the management practices and site to reach

the desired vine size and vigor. For example, high vigor rootstocks are best suited

for lower vigor sites (such as shallow or infertile soils) or for less invigorating

management practices (such as deficit irrigation). Nematode resistant rootstockscan be found across a range of vigor induction.


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This location, in the southwestern Sacramento Valley of California, is a low vigor

site. It is on a hillside, with relatively shallow soil of low fertility. Rainfall at this

site is about 18-20 inches annually, but the hillside location is very well drained.

The water table is well below the root zone. High vigor rootstocks can be used

appropriately at this location.


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This location, in the central part of the Napa Valley of California, is a high vigor

site. It is a valley floor site, with deep fertile soil. The water table can be as shallow

as 5 feet, so vines are rarely water stressed. On this more vigorous sites, less

vigorous rootstocks should be used. For example, in this well watered, deep, fertile

valley floor soil, 1616C, 101-14 Mgt, and perhaps Schwarzmann would be useful.

Both this high vigor site and the previous low vigor site are subject to damage from

nematodes.


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101-14 MgtSchwarzmann3309C

Rootstocks belong to families, just like people, and the members of rootstock

families share similar horticultural characteristics. They are often similar in soil

adaptation and vigor induction, although nematode resistance can vary among

rootstocks in the same family. Because of shared characteristics within families,

often there will be a rootstock with good nematode resistance for a given site.

These rootstocks are all members of the V. riparia x V. rupestris familythey have

similar horticultural characteristics, although not identical, and all offer durable

protection against phylloxera. Their soil adaptation is similar, but they differ in

nematode resistance. 3309C is mostly susceptible to nematodes, while

Schwarzmann and 101-14 Mgt offer resistance against many nematode populations.


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5C

The V. berlandieri x V. riparia family of rootstocks provide durable protection

against phylloxera and are well suited to high pH calcareous soils. 5C and 5BB are

V. berlandieri x V. riparia rootstocks with good resistance to many nematode

populations.


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5BB


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420A

420A is another member of the V. berlandieri x V. riparia rootstock family. 420A

is a low to moderate vigor rootstock and has been shown to reduce pruning weights

while maintaining or increasing yield. 420A has been demonstrated to be resistant

toMesocriconema xenoplax, the ring nematode.


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110 R

The V. berlandieri x V. rupestris rootstock family members provide excellent

protection against phylloxera. The rootstocks in this family include 110R, 140 Ru,

and 1103P. Most of the rootstocks in this family are moderately to highly vigorous

and several are well adapted to dry hillsides. 1103P has excellent nematode

resistance.


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1616 Couderc

1616C is a low vigor nematode resistant rootstock. This rootstock tends to decrease

vine size.


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44 53 M

44-53 Malegue has been reported to provide protection against fanleaf degeneration.

However, this is not supported by rootstock trial data. 44-53 M does provide

protection against phylloxera.


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Freedom

Freedom is a moderately high vigor rootstock, with good resistance to root-knot

nematodes andXiphinema. index dagger nematodes. Although resistant to

Xiphinema index dagger nematodes, Freedom does not provide protection against

fanleaf degeneration. So far, Freedom has been adequately resistant to phylloxera.

However, Freedom has V. vinifera in its background, which may have implications

for the long term phylloxera resistance of this rootstock. The closely relatedrootstock Harmony, although highly resistant to root-knot nematodes, is not resistant

to phylloxera and is not recommended for vineyards where phylloxera may be a

problem.


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Riparia Gloire

Rupestris St. George

Riparia Gloire and Rupestris St. George are important rootstocks that have been

used successfully for many years to provide protection against phylloxera. Riparia

Gloire is a low to moderate vigor rootstock, while Rupestris St. George is a

moderate to high vigor rootstock. Although they provide excellent protection

against phylloxera, Rupestris St. George and Riparia Gloire are considered

susceptible to many nematode populations.


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1613 Couderc

AxR#1

Rootstocks of

the past

Some rootstocks are no longer recommended and should not be planted

because they are susceptible to phylloxera. 1613 C is resistant to many nematode

populations. Axr#1 is nematode susceptible. Both are insufficiently resistant to

phylloxera. Rootstocks with superior phylloxera protection as well as excellent

nematode resistance are available that should be used instead of these and other

phylloxera susceptible rootstocks.


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Rootstocks of the future

10-17A 10-23B PC0188-151

New rootstock selections and varieties are under evaluation and development. 10-

17A and 10-23B are USDA ARS selections that are resistant to a broad range of

nematodes, including endoparasites and ectoparasites. PC0188-151 is another

nematode resistant USDA ARS selection currently in wine grape rootstock trials.

The University of California last year released five new rootstocks with broad

nematode resistance; vineyard evaluation will determine the adaptation of newrootstocks to vineyard conditions.


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Leafroll disease symptoms on a red wine grape variety. Leafroll disease and other

virus diseases reduce grape quality and yield. Always use virus tested planting

material, both in grafted and own-rooted vines. Both rootstock and scion should be

virus tested plant material.


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This is an example of the nematode resistant rootstock Harmony and how it grows

differentially when infected with corkybark disease, which is caused by a virus (the

picture on the right is the virus infected, diseased plant and the picture on the left is

of the healthy plant. Many nematode resistant rootstocks seem to be quite sensitive

to virus infected scions. Chose virus tested scion and rootstock plant material for

your vineyard to help manage the risk of this problem.


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Rootstocks are an economically and environmentally sustainable nematode

management practice. Rootstocks can reduce the damage caused by nematode

feeding on grapevine roots and provide durable protection against nematodes for the

life of the vineyard.

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