smart v it trunk renewal october 2015

8/20/2019 Smart v It Trunk Renewal October 2015

http://slidepdf.com/reader/full/smart-v-it-trunk-renewal-october-2015 1/764 PRACTICAL WINERY & VINEYARD October 2015

T

runk diseases threaten vine-yards around the world, and the

International Organization ofVine and Wine (OIV) has now

taken an active interest. This columndescribes a new systematic approach toovercome trunk diseases in mature vine-yards. The basic concept of timely trunkrenewal (TTR) is certainly not new, butthe application to trunk disease—espe-cially to entire vineyard blocks — is prac-ticed by very few growers.

Trunk renewal is not a new processfor California. University of CaliforniaExtension workers Jim Kissler and BobSisson used trunk and cordon renewal in

the 1980s and showed that that retrainingfrom the cordon or the trunk works verywell for infected vines.

However, the process and its applicationto the present battle with trunk diseasesgenerally has been overlooked. The pres-ent emphasis in California is to encourageearly preventative practice such as doubleor late pruning and wound protectionwith chemicals.

In the past five years I have interactedwith many scientists in the internationaltrunk disease research community. Severalof them made useful comments on a draftprotocol for trunk renewal, which have

been incorporated below.

Grapevine trunk diseasesThere are four major grapevine trunk dis-eases, all caused by different, taxonomi-cally unrelated fungi. These diseases arecalled Esca, Eutypa dieback, Botryosphaeriadieback and Phomopsis dieback.

Esca is a major problem in Europe, butit is less common in California.

Eutypa dieback occurs around the worldand in California. It is the trunk diseasethat has been the most thoroughly exam-ined on a scientific basis.

Botryosphaeria and Phomopsis diebackare also global but not so well understood

by researchers nor recognized by manygrowers. The extent of Botryosphaeria infec-tion in California relative to Eutypa wasdescribed by J.R. Úrbez-Torres (2006).

There is presently no single, universallyagreed control strategy for these diseasesonce they are established in the vineyard.My belief is that trunk renewal will fillthat role, just as the use of grafted grape-vines led to control of phylloxera.

Grower attitudes vary as to how mucdamage is a threshold level for removand replanting, but I hear a figure of 20yield loss frequently. California economstudies indicate that early intervention wound protection is necessary to restridisease spread and loss of income, mucearlier than 20%.

Trunk renewal in perspectivePresent recommendations for trundisease control in California are fopreventative action starting in younvineyards and include delayed pruing or double pruning and treatmeof pruning wounds with fungicidsuch as Topsin M (thiophanate-methyUnited Phosphorus Inc., King of PrussiPenn.) and Rally (myclobutanil; DoAgrosciences LLC, Indianapolis, Ind

before a rain event or with non-chemcal materials, such as boric acid (TecGro B-Lock; Nutrient Technologie

Inc., Dinuba, Calif.) or VitiSeal (VitiSeInternational LLC, San Diego, CalifBoric acid only controls Eutypa, bwith addition of Topsin M all diseasare controlled.

TTR can be seen as supplementary these procedures, namely in mature vinyards, and allows for the treatment early symptom vines and those most risk because of their location near infectevines.

S M A R T V I T I C U L T U R E by Dr. Richard Smart

Figure 2. A vine in England with two suckers in line with the vine row and on both sides of the

trunk. These are ideally placed to replace the existing diseased trunk with two healthy trunks,

each one supporting a cordon. The trunk could be removed either the following winter or the next

winter, with minimal or no crop loss.

The principal means of spread of trunkdiseases is by winter pruning-wound

infection with wind-dispersed or splash-dispersed spores (depending on thepathogen), which are released in rainyweather. Trunk diseases are insidious,especially Botryosphaeria dieback, whichdoes not show symptoms until long afterinfection.

Surveys from grapevine nurser-ies around the world have detected thecausal pathogens of Esca and Black foot,and other fungi contaminating graftedvines, which can lead to infection in newvineyards. Thus, the problem will likelyworsen.

The damageUnder extreme conditions, vine deathdue to Esca and Botryosphaeria can occur

before the vine matures and begins to formfruit, but commonly they and the othertrunk diseases first show symptoms (deadspurs, stunted shoots or foliar symptoms)

between five and seven years of age. Asmore and more vines develop symptoms,yields decline.

Timely Trunk Renewal toOvercome Trunk Disease


http://slidepdf.com/reader/full/smart-v-it-trunk-renewal-october-2015 2/7October 2015 PRACTICAL WINERY & VINEYAR

S M A R T V I T I C U L T U R E

We are all familiar with vineyards whereindividual vines are trained to a singletrunk as has become the convention, butit is only a convention. In nature, and forabout 40 million years, Eurasian vineshave been forest dwellers; vines have beenmulti-trunked and unpruned, see Figure 1.

It is probably in the past 5,000 years orso that vineyards have been monocultures,with each vine trained to a single trunk.Multi-trunks are a practice used com-mercially in places with severe wintersto replace cold-damaged trunks, such asin New York state, and to combat crowngall that sometimes develops on cold-damaged trunks. It can be used to fighttrunk diseases, too.

East Coast-based viticulturist LucieMorton suggests growers start out withtwo trunks to help with the inevitabledevelopment of trunk diseases, and I thor-oughly endorse this. It can also lead toearlier yields from new vines.

Scientific studies in Australia since 1988have shown that the cumulative yieldlosses due to Eutypa dieback can be miti-gated by taking healthy suckers from the

base of the vine to replace the trunk. Thistechnique works with other trunk diseasesalso. It takes advantage of saving the vineroot system.

Suckers arise from “base” buds atprior node positions on the vine trunk.Depending on circumstances, a proportionwill burst in any growing season. Theseare typically seen as a nuisance by vine-yard managers, who will normally have aprogram to remove them, either manually,mechanically or by chemical spray. Timelytrunk renewal depends on the presence

of suckers and can lead to a totally newattitude to suckers if trunk diseases arepresent in a vineyard. The catch cry may

be, “Save those little suckers!”Trunk renewal can be a “cure” for trunk

disease, in that a diseased trunk and cor-dons are replaced with healthy, new partsto eliminate the infection. This helpsimprove yield and may slow the spread

of disease by removing potential inoculumsources from a vineyard. There is, how-ever, no guarantee that re-infection willnot occur, and pruning wounds must beprotected by fungicide application.

Growers might contemplate replaone trunk with two, as done in the easUnited States. These new trunks canfree of trunk disease infection if locsufficiently low on the trunk, below wcankers or discoloration due to the trpathogens. Australian guidelines gest a 4-inch separation below stainin New Zealand, the recommendatio

8 inches.An alternate approach that maymore suited to working with a vineycrew is to cut at a fixed height 12 inabove ground. One grower in Cog

Figure 1. Dr. Pierre Galet, French scientist,

with a native Vitis Berlandieri vine in the Davis

Mountains of Texas. Note the multi-trunks

and their spread along the ground.

L U C I E

M O R T O N




France, cut off higher, at 18 inches, andthe dead trunk was useful support forreplacement suckers and plastic vineguards during retraining. Whicheverheight is chosen, this should be approxi-mately 8 inches below any staining on themost affected vines.

Aims and application of TTR

Given that “trunk/cordon renewal” is anaccepted strategy for trunk disease (in thesense that the infection may be removed),the pertinent question is when should it

be applied?Should the process be initiated with

observation of the first dead cordonor vine? Or, should one wait until thedisease is seen to be more widespreadthroughout the vineyard (10% or 20%symptomatic vines). Should only the verydevigorated vines be treated with trunkrenewal, or perhaps should adjacent

vines showing the very first symptoms—or even no symptoms—be included?

There is the question of what should bedone, and to how many vines? Removingall trunks in one year will cause obviouscrop loss, yet some growers are inclinedto treat all vines in a block the same way,even though they may suspect that infec-tion varies. Other growers compromise

by doing portions of a block in consecu-tive years (including replacement oftraining wires), to spread out yield loss.

In any event, the most expensive wayof treating trunk disease is total trunkrenewal in a block, as it involves unnec-essary crop loss for the sake of “man-agement uniformity.” Sucker trainingto new trunks and arms can precedetrunk removal, and no crop need be lost.Replacing the removed vine frameworkis achieved more quickly with two newtrunks, although I understand that some

Figure 3. A 30-year-old Sauvignon Blanc vine

in Martinborough, New Zealand. Were the

trunk not renewed 10 years ago, it would have

died from trunk disease. Now it is healthy.

Low infection Medium Infection High InfectionTable 1 (0% – 2%) (2% – 10%) (more than 10%)

Low risk 1 2 3

Medium risk 2 3 3

High risk 3 3 4


http://slidepdf.com/reader/full/smart-v-it-trunk-renewal-october-2015 4/7October 2015 PRACTICAL WINERY & VINEYAR


managers may be concerned with such a departure from con-vention.

Removal of the old trunk can be an issue. Especially if spur-pruned, the fruiting wires may be ingrown in the wood, andoften trunks, cordons and wires need be removed, and trunksdestroyed.

The broad aim of the TTR protocol is to reduce the impact ofgrapevine trunk disease on vineyard profitability. The protocolaims to:

1) Retain health and recover yields to profitable levels, beforeyield losses are too severe.2) Manage the disease to conserve production where possible,

in vineyards at an early to moderate stage of infection, orthose with a higher risk of infection.

3) Minimize costs and maximize revenue in all instances.

General assumptions1) The protocol defined below is not applicable to vines with

unhealthy root systems, which may be caused by root patho-gens or for other reasons, or to vines with other diseasessuch as virus.

2) The cordons and, to a lesser extent, the trunks of maturevines are likely to have more wood cankers and discolor-

ation than those of young vines. The greater the proportionof such wood symptoms, the greater is the impact on yield.

3) Present abiotic stresses may compound damage from trunkdisease. Sometimes the stress should be addressed beforetrunk renewal, as for example with poor soil drainage.

4) Use of healthy suckers arising from base buds well belowwood symptoms offers the opportunity for trunk renewalwhile retaining the original root system.

Vineyard procedures for the protocolNormally a vineyard is made up of discrete blocks, which maydiffer in grape variety, clone, rootstock and date of planting etc.The following protocol is designed to be applied at the block level.1. Trunk disease infection assessment: Each block needs to beassessed for trunk disease, and this assessment can be at vari-ous degrees of accuracy, from visual ratings of numbers of deadspurs per vine, for example, to counts of vines with the presenceof canopy symptoms. Dead, missing vines, replants and other-wise symptomatic vines need to be recorded also.

Timing of inspection depends on the predominant trunk dis-eases in the vineyard. Foliar symptoms of Eutypa are most appar-ent in spring. Symptoms of Esca do not start to develop untilapproximately mid-June. Dead spurs and stunted shoots are bestobserved later in the growing season, when vegetative growthceases.2. Trunk disease risk assessment: All vineyards in California areattacked by one or more trunk diseases, eventually. Obviouslythe older the vineyard, typically the greater the level of damage.The time it takes for canopy symptoms to first appear, the rateat which the proportion of symptomatic vines increases and theseverity of yield losses are all influenced significantly by grapevariety.

The varieties Sauvignon Blanc and Ugni Blanc are among themost susceptible to Esca. Merlot seems to be more resistant toEutypa dieback than Cabernet Sauvignon, although they are bothsimilarly susceptible to Botryosphaeria dieback. In California, seed-less table grapes (namely Thompson seedless) are very suscep-tible to Phomopsis dieback.

It is not possible to present a general table of trunk diseasesusceptibility, since experience suggests that this may vary fromregion to region, maybe vineyard to vineyard. The best approach




Multi-trunking for vine longevity By Lucie Morton

Because U.S. grapegrowers with vineyardseast of the Rocky Mountains can experi-ence very cold winter temperatures, thepractice of maintaining more than a sin-gle trunk from the start is common. It is

especially critical for those growing Vitisvinifera varieties as opposed to traditionalnative American vines and hybrids withgreater cold tolerance.

Today, as the relatively young wineindustry and its vines mature, it has

become clear that this practice will alsoprolong the life of a vineyard by renewingaging and diseased vascular systems.

As Richard Smart discusses—and asearch of the International Council ofGrapevine Trunk Diseases (ICGTD) web-site icgtd.ucr.edu will confirm—there aremany different fungi involved in vine

decline caused by xylem plugging andwood dessication. These fungi can coexistwith vines for many years without beingparticularly detrimental, or they can leadto problems with vines of all ages startingwith very young plants in the nursery.

As with any disease complex, climate

has a huge influence on which symptomsand associated fungi are more prevalentand how much their presence will affectvine health. Th e eastern United Statesincludes Florida in the south stretching to

Ontario, Canada, in the north and west-ward to the Rockies.

Farm wineries in this region are gener-ally small in size. For example, the twolargest vineyards in Virginia hover around200 acres, but many are much smaller.Most vineyards are far apart geographi-cally and in sites that have not had vine-yards previously. Therefore, wind-blownspores from neighboring vineyards are nota big problem. Fungi introduced by plantmaterial from elsewhere may or may notsurvive in this new environment.

My photo of a circa 25-year-old Cabernet

Sauvignon/5BB vine planted in the mid-1970s in Virginia shows the progression ofEsca disease three different-aged trunks onthe same vine. I took the photo in about1999 in a Virginia vineyard with 20-plusyear old Cabernet Sauvignon vines thatwere being pulled out.

Multiple trunking was done here asa hedge against winter damage. Thesetrunks are 22, 15 and seven years old. Petridisease was very much in the forefront ocontroversy then (1998 being the founding

of the ICGTD and 1999 being the first international meeting in Siena), and by then ihad been linked to Esca and vine decline.

This vine has all the symptoms of clas-sical Esca disease where there is black goostaining in young xylem tissue, brownwood in older wood, and the classic whiterot caused when basidiomycetes finish ofwhat ascomycetes starts. Occasionallythere will be tell-tale “tiger-stripe” foliarsymptoms perhaps due to Botryosphaeirafungi in the mix with the Phaeomoniellasand Phaeoacremoniums.

To protect one’s investment from losing

economic viability over time, one shouldconsider a combination of close vine spac-ing, cane pruning, multiple trunking and/or trunk renewal. Like grafting, it bringsalong some extra cost and cultural incon-venience that should be factored in with anincrease in productive lifespan.

SELL TO MORE GROWERSThe Wines & Vines

Grower Online Marketing

System (GOMS) enables

users to create and save

highly customized grower

searches, and export

results into advanced

report types, data exports

and mailing labels.

(866) 453-9701 • winesandvines.com/OMS

SELECT RECORDS BASED ON:SELECT RECORDS BASED ON:

region

varietals

acreage

grape sales

new vineyard


http://slidepdf.com/reader/full/smart-v-it-trunk-renewal-october-2015 6/7October 2015 PRACTICAL WINERY & VINEYARD


for growers and their advisers is toand develop guidelines for their lregion.

That said, resistance to one trunk ease does not confer resistance to anotBecause the trunk diseases occur in minfection in a vineyard, growers shoassume that multiple diseases will be pent.

3. Combining risk and infectiondecide an appropriate managemstrategy. Table 1 has three classes of and three classes of infection, and a sof four suggested management stratefor each cell in the table. The infecvalues in the Table 1 heading are indtive only, and may vary from regto region and vineyard to vineyardapplication.

Strategy 1: Pre-harvest inspectiogenerally not necessary, as some sytomatic and dead vines are evidenwinter pruning. Remove dead vines

burn. Encourage and retain suckerssymptomatic vines, and commence trrenewal.

Strategy 2: Perform pre-harvest instion to identify early stage symptomvines. Begin trunk renewal for any sytomatic vines and adjacent vines if cluing and staining are evident.

Promote your wines to leadingZinfandel enthusiasts and extend yourwinery’s relationship in the market.

Join Us!We are champions of Zinfandel—

America’s Heritage WineBecome part of our proud legacy

zinfandel.org • 530-274-4900

Zinfandel Advocates & Producers is a 501(c)(3) non-profitorganization. ZAP is dedicated to advancing public

knowledge of and appreciation for American Zinfandeland its unique place in our culture and history.

You knowhow good yourZinfandel is...

SUBSCRIBE ONLINE & SAVE!winesandvines.com/subscribe

Print + Digital Magazine

12 monthly issues a year for $28

winesandvines.com/subscribe

Esca progression in three different age trunks from one original vine root system.

L U C I E

M O R T O N




Strategy 3: As above, and begin programof water-shoot generation and training toreplace all trunks within one or two years.

Strategy 4: For all vines, winter-prunevery hard, remove all trunks in spring,train suckers for replacement trunks, or,remove all vines and replant.

Notes

• Basal suckers may be encouraged by ahard pruning in winter followed by latespring trunk removal. They may also beencouraged by careful bark removal onpart of the basal trunk. Suckers may needto be trained in transparent plastic tubesto protect them from herbicides, and gen-erally they need to be staked or tied to thetrunk as they can break off easily in thefirst year. Plastic tubes can provide train-ing support. Suckers will usually growvery strongly, even if the parent vine isnot immediately removed. Often a reason-able bud number can be retained at winter

pruning at the end of the first growingseason, to produce some yield in the fol-lowing growing season. This is facilitated

by training two new trunks per vine.• When removing trunks, the cut should

be below the stain by 4 to 8 inches,and the final cut should be made at a45° angle, facing south for the Northern

Hemisphere. This assists drainage of sapand drying the cut surface.• Treat all wounds with a protectantfungicide, especially large cuts and espe-cially if this is being done in the dormantseason.• Remove all vine parts from vineyardand burn as soon as possible.• Encourage two suckers—one on each

side of the vine—in line with the vinerow. If small, spur-prune them in winter.Two suckers can be used to form twotrunks, a helpful insurance against newinfections, or an extra in case of damage.• It is imperative to protect new trunksand cordons from infection. Protect-ing a pruning wound with a fungicidespray, paste or paint/fungicide mixtureis strongly suggested. Fungicide spraysonly provide protection for about twoweeks. Avoid making pruning cuts inwet weather.

ConclusionAdoption of this protocol will allow vine-yards to recoup some losses from the rav-ages of trunk disease, assuming you timeit before significant yield losses alreadyhave occurred. The sooner the protocol isadopted, the less loss of yield there will be,and the infection will spread more slowly.

The aim was to develop a systematmethod for growers to address trunk diease issues in commercial vineyards, they might maintain vineyard productiity while at the same time containinspread of the diseases. Experience in mancountries shows that the sooner that trunrenewal begins, the more successful it w

be to control spread of disease and yie

loss. PWV

AcknowledgementsThe author gratefully acknowledges valable input from Kendra BaumgartneDoug Gubler and Rhonda Smith (UDepartment of Agriculture AgriculturResearch Service, and University California). Their California experienhas much improved the column, as hthe editor’s input.

Editor’s note: For more information, gto practicalwinery.com. Back issue

“Research update: Grapevine trunk dieases in California,” Janary/February 2005.

Dr. Richard Smart is a qua fied and experienced viticultuist. Contact him at vinedoctorsmartvit.com.au.

Keep your business going

strong with new and improved

Western Square barrel racks.westernsquare.com n 209.944.0921

WESTERN SQUARE

I N D U S T R I E S

When was the last time you replaced your old barrel racks?

Are you confident your barrel racks are still safe and secure?

For over 30 years, we at Western Square have been in the

business of helping you build yours.

Our barrel racks are:• Affordable and won’t break your budget• Able to accomodate over 7,000 lbs. of materials—

ensuring the safety of you and your employees.

Holding your business together,

one rack at a time.

smart v it trunk renewal october 2015

Documents