PREVENT TRUNK DISEASES IN YOUNG VINEYARDS MANAGEMENT IN MATURE VINEYARDS
Guide to
Start preventive practices before symptoms appear in young
vineyards (less than 5 years old), beginning at the first dormant
Preventive practices maintain yields by reducing the chance
of new infections, but they do not eradicate trunk diseases. In Vineyard Trunk
pruning. Trunk pathogens infect primarily through pruning
wounds by rain-induced spore release during the dormant season
in California.
addition to preventive practices, management in infected mature
vineyards includes:
Sanitation. Prune away dead spurs or cordons with wood
Diseases
1) Delay pruning until February or later. Schedule hand or cankers, and burn or remove infected wood from the vineyard. IN CALIFORNIA
mechanical pruning in February or later. Pruning wounds made When it rains, all trunk pathogens produce spores from infected
in early winter (December or January) are very susceptible to wood. Therefore, removing or burning wood eliminates local
infection: sources of inoculum.
• winter rains induce spore release, and Trunk diseases (wood-canker diseases) threaten
• cold temperatures lengthen the wound-healing process.
Sanitation and surgery create large wounds. Perform
sanitation and surgery in February or later and apply all California vineyards due to widespread
In contrast, pruning wounds made in mid- to late winter
(February or later) are at lower risk of infection because rain is a pruning-wound protectant. distribution of the fungal pathogens. The
less frequent and wounds heal soon after pruning. infections are chronic and occur each year. Trunk
Double pruning is a type of delayed pruning for cordon- Surgery. Cut off the vine just above the graft union and train diseases in mature vineyards reduce yields and
trained, spur-pruned vineyards and involves two passes: a trunk sucker as a new trunk (Figure 11). Use a T-bud or other
graft on vines without trunk suckers. Success depends on increase management costs to the point where
• Pass 1 ( December or January) – Often with a mechanical
pruning machine, canes are prepruned to about 10 to 12
complete removal of infected wood, which is difficult to achieve the vineyard is less profitable.
because trunk pathogens are often present in healthy-looking
inches above last year’s spurs. No cuts are made down to the wood. Pathogens are less common in the base of the trunk and
K. BAUMGARTNER
R. TRAVADON
cordon. using a trunk sucker should result in a new vine with less disease.
• Pass 2 (February or later) – Canes are pruned to 2-bud spurs. This aggressive approach removes the pathogen and starts the
This removes the section of the cane that may have been retraining process to replace fruiting spurs or canes.
infected via pruning wounds made during Pass 1. In vineyards with many symptomatic vines, surgery can be done
2) Protect pruning wounds, when pruning prior to February. on a row-by-row or block-by-block basis to ensure uniform
Fungicides that prevent infection of pruning wounds are growth of whole sections of the vineyard.
labeled for dormant-season use in California (refer to the
M. COOPER
Grape Pest Management Guidelines). In addition, there
are other nonfungicidal materials that provide a physical
barrier to infection. All pruning-wound protectants must
remain continuously active for 30 days if vines are pruned
in December or January. Reapplication may be necessary,
depending on the protectant used and the timing of its first
application with respect to rain. Rain triggers spore production
and washes protectants off pruning wounds.
3) Inspect plant material before planting and provide proper
care for young vines in newly-established vineyards.
Young vines infected by Botryosphaeria dieback, Petri Disease FIGURE 11
(form of Esca that attacks young vines), and Phomopsis
dieback may be further harmed by abiotic stress (e.g., over- Use this guide to identify trunk diseases and inform management
or underwatering, overcropping, improper planting). Weak For more information, visit the Grape Pest Management decisions. It is not critical to identify the specific fungal pathogen
Guidelines http://www.ipm.ucanr.edu/PMG/ because the management practices are similar and more than
growth from the combined infection and abiotic stress may selectnewpest.grapes.html
doom a vineyard to a lifetime of poor productivity. one pathogen is typically present. This guide will help you:
Authors: Monica L. Cooper, Larry J. Bettiga, Rhonda J. Smith
(University of California Cooperative Extension); Renaud • recognize the trunk disease complex as a problem
Travadon (Department of Plant Pathology, University • understand the preventive practices
of California, Davis); Kendra Baumgartner (USDA-
Agricultural Research Service, Davis, CA).
• adopt preventive practices in young vineyards
Funding provided by USDA-NIFA Specialty Crop • perform these practices at appropriate times on an
Research Initiative. annual basis
DO YOU HAVE A TRUNK DISEASE? ESCA (BLACK MEASLES)
Common symptoms typical of all trunk diseases: Symptoms diagnostic of Esca (Black Measles):
M. COOPER
• dead spurs (Figure 1) • leaf symptoms (Figure 5)
Fruit spots are visible on
• stunted shoots (Figure 2) • fruit spots (Figure 6) white cultivars of wine
• wood symptoms (Figure 3) • concentric rings of black spots (Figure 7) grapes (e.g., Sauvignon
Damage to a cordon or trunk from abiotic factors (e.g., girdling Main Esca pathogens: Phaeomoniella chlamydospora, blanc, shown here)
from wire, sunburn, mechanical injury, spray damage) can appear Phaeoacremonium aleophilum (teleomorph Togninia minima), and table grapes (e.g.,
to be a trunk disease symptom (Figure 4). Vines heal from these and other Phaeoacremonium species Thompson seedless).
physical injuries and may form new tissue around the wound,
K. BAUMGARTNER
M. COOPER
distinguishing such damage from that of a trunk disease. FIGURE 6
K. BAUMGARTNER
R. SMITH
Dead spurs are found even
in the dormant season. This
dead spur, photographed Concentric rings of black
in December, is flanked by spots surround the pith
apparently-healthy spurs (the naturally darkened
FIGURE 5
with canes. core) of this cordon.
FIGURE 1
Leaves with interveinal necrosis appear in mid-summer. The
margin outlining the necrosis is reddish brown in red cultivars FIGURE 7
L. BETTIGA
Stunted shoots are most (left, Cabernet Sauvignon) or yellow in white cultivars (right,
apparent in early summer. Sauvignon blanc).
Healthy-looking shoots
continue to grow, but shoots
on infected spurs (second spur EUTYPA DIEBACK BOTRYOSPHAERIA DIEBACK AND PHOMOPSIS DIEBACK
from the end of this cordon)
die back. Symptoms diagnostic of Eutypa dieback: There are no diagnostic canopy symptoms. These two trunk
FIGURE 2
• stunted shoots with deformed leaves (Figure 8) diseases are best characterized by one or more of the general
trunk symptoms (Figures 1, 2, and 3):
• shortened internodes (Figure 9)
R. TRAVADON
• dead spurs
Internal wood symptoms Main Eutypa dieback pathogens: Eutypa lata and other species in
are found year round. the same family (Diatrypaceae) • stunted shoots
Cross-sectional cuts of the • wood symptoms
L. BETTIGA
R. TRAVADON
permanent woody structure Main Botryosphaeria dieback pathogens: Neofusicoccum parvum,
of the vine (spurs, cordons, Diplodia seriata, Lasiodiplodia theobromae, and Botryosphaeria
or trunk) expose cankers dothidea
(rotten zones of the wood)
that vary widely in shape, Main Phomopsis dieback pathogen: Phomopsis viticola, which also
color, and texture. causes Phomopsis cane and leaf spot, a disease with diagnostic
FIGURE 3 canopy symptoms (Figure 10). The relationship between canopy
symptoms of Phomopsis cane and leaf spot and wood symptoms
of Phomopsis dieback is not well understood.
M. BATTANY, UCCE SAN LUIS OBISPO
MIZUHO NITA, VIRGINIA POLYTECHNIC INST. & STATE UNIV.
FIGURE 8 FIGURE 9
Characteristic leaf symptoms
Stunted shoots have Stunted shoots with
of Phomopsis cane and leaf
deformed leaves with shortened internodes
spot appear in early spring
necrotic, tattered margins. may have a zig-zag pattern
on lower leaves of infected
FIGURE 4 These canopy symptoms are of growth.
shoots.
most apparent in spring.
Stunted shoots (left) on a cordon wrapped too tightly to the
training wire will girdle the cordon as it grows (closeup at right).
This is not a symptom of trunk diseases. FIGURE 10
