Crown Gall in Vineyards: Identification and Management Guide

By VitiScribe Editorial·March 22, 2025·Updated May 8, 2025

Crown gall infection is often triggered by freeze injury, creating entry wounds through which the pathogen enters vine tissue. This relationship between cold injury and crown gall incidence is why the disease is most severe in cold-climate wine regions and in years following extreme winter cold events. The 2014 polar vortex left crown gall damage across eastern US vineyards for seasons afterward as Agrobacterium vitis exploited the freeze wounds.

TL;DR

Crown gall is caused by Agrobacterium vitis, a systemic soil-borne bacterium that colonizes the vascular system of infected vines -- you cannot eliminate it from an infected vine by soil treatments
Temperatures below 5°F (-15°C) typically cause notable grapevine freeze injury; crown gall in freeze-damaged blocks typically appears 1-3 years after the cold event
Pruning tool contamination is a primary within-vineyard spread route; disinfect with 70% isopropyl alcohol or 10% bleach solution between vines in confirmed-infected or high-risk blocks
For new plantings, Agrobacterium radiobacter K84 (Norbac 84C) root dip at planting provides biological control -- it is preventive only and not effective against established infections
When crown gall incidence in a block exceeds 20-25% of vines, the economic impact on production typically justifies replanting; document annual incidence trends to support this decision with data
VitiScribe's block-level scouting records track annual crown gall incidence, minimum temperature events, and multi-season spread trends to build the historical documentation that replanting decisions require

Block-level crown gall records in VitiScribe track disease spread and cold-injury correlation over time, giving you the historical data to understand which blocks are most vulnerable, which vintages drove infection events, and whether disease incidence is stable, spreading, or declining in response to your management approach.

Biology of Crown Gall

Crown gall is caused by Agrobacterium vitis, a soil-borne bacterium that infects grapevines through wounds. Unlike most plant pathogens that kill host cells, A. vitis inserts part of its own genetic material (Ti plasmid) into host plant cells, causing those cells to proliferate abnormally and form the characteristic galls -- tumor-like growths at wound sites.

The pathogen lives in the vine, not just the soil. This is a critical point that distinguishes crown gall management from most soil-borne diseases. A. vitis is a systemic pathogen that colonizes the vascular system of infected vines. You cannot eliminate A. vitis from an infected vine by soil treatments, and replanting in a site with infected vines doesn't remove the pathogen from the vineyard.

Infection requires wounds. Fresh wounds create the entry points that A. vitis needs for infection. In vineyards, the most important wounding events are:

Winter freeze injury: The most common crown gall trigger. Freezing and thawing of vine tissue creates extensive internal wounds. A. vitis in the soil or on vine surfaces enters through these wounds when temperatures moderate.
Pruning wounds: Fresh pruning cuts can serve as infection sites, though they're typically less notable than freeze wounds.
Mechanical damage: Harvesting equipment, cultivation equipment, wire tension cracks at stake contact points.
Graft unions: The graft union is a wound site that remains susceptible through the life of the vine.

Identification

Crown gall produces visible symptoms that, once seen, are unmistakable.

Galls: Irregular, rough-surfaced, tumor-like growths at wound sites -- most commonly on vine trunks at or near the soil surface, at graft unions, at cordon bends, and at pruning wound sites. Galls range from small marble-sized growths in early infection to large, fist-sized masses in established cases. Gall tissue is soft and spongy when young, hardening and darkening with age. In cross-section, gall tissue has an irregular, disorganized internal structure.

Gall location: The most common location is the trunk at or below the graft union, reflecting that A. vitis in soil contacts vine tissue most readily at this zone. Winter freeze damage drives galls to appear at whatever tissue was most damaged -- sometimes mid-trunk, sometimes at cordon level depending on how cold temperatures progressed down through vine tissue.

Vine decline: Galls obstruct vascular flow when they form at the trunk or cordons. Heavily galled vines show reduced vigor, poor shoot growth, delayed budbreak, and reduced fruit load. In severe cases, vine decline over 2-5 years is the result.

Distinguishing from Eutypa/Botryosphaeria: Trunk disease cankers don't produce external galls. If you see surface growths at wound sites, think crown gall rather than wood-internal diseases like Eutypa.

Freeze Injury as the Primary Driver

Understanding the freeze injury-crown gall relationship helps you predict when and where crown gall will appear after cold winters.

The biological relationship: A. vitis produces a compound that stimulates Ti plasmid transfer and gall formation more effectively when vine tissue is stressed. Freeze-damaged tissue sends chemical signals that A. vitis responds to, entering through wound sites and triggering gall formation more readily in damaged tissue than in healthy tissue.

Predicting post-freeze crown gall incidence:

Temperatures below 5°F (-15°C) typically cause notable grapevine freeze injury
Crown gall in freeze-damaged blocks typically appears 1-3 years after the cold event
Varieties with high cold hardiness (cold-hardy hybrids, Riesling, some Cabernet Franc selections) show less freeze injury and less subsequent crown gall incidence
Young vines and newly established plantings are more susceptible than mature vines

In VitiScribe, record winter minimum temperature events alongside crown gall incidence observations. Blocks where you document extreme cold winters followed by crown gall emergence years later build a predictive model for your operation -- you'll know which cold events put which blocks at risk. See block GPS mapping for tracking disease incidence location within blocks.

Spread Between Vineyard Blocks

A. vitis can move between blocks through several routes:

Equipment: Pruning shears, chainsaws, and other cutting tools can carry A. vitis from infected vines to healthy ones. Disinfecting pruning tools between vines in high-risk or confirmed-infected blocks is standard IPM practice. A 70% isopropyl alcohol solution or 10% bleach solution are common disinfection approaches. Log tool disinfection practices in your IPM documentation.

Irrigation water: A. vitis can be moved in irrigation water from contaminated soil, particularly in flood irrigation systems or when drainage from infected areas reaches new planting sites.

Planting material: Infected nursery stock is one of the most notable routes of introduction into new vineyards. Request phytosanitary certificates and inquire about crown gall testing protocols from your vine nursery.

Nematodes and other soil organisms: Some research indicates that A. vitis can move short distances in soil with soil organisms, though this is a slower transmission route than infected planting material or contaminated equipment.

Management Options

There is no registered bactericide for A. vitis in established vineyard blocks. Management focuses on prevention and on limiting disease spread once present.

New planting prevention:

Source vine material from certified nurseries with crown gall testing protocols
Soil drench with Agrobacterium radiobacter strain K84 (Norbac 84C, Galltrol): biological control agent that colonizes vine roots and produces a bacteriocin that prevents A. vitis infection. Apply as a root dip before planting. Not effective against established infections, only as a preventive for new plantings. Note that K84 is not effective against all A. vitis strains -- inquire about strain efficacy from your biological control supplier.

Cultural management in established blocks:

Minimize vine wounds during the infection-risk period (winter through early spring)
Disinfect pruning tools between vines in blocks with known crown gall history
Manage winter freeze risk through cultural practices (delayed pruning, trunk protection) in regions with freeze injury risk
Remove severely galled vines rather than attempting to manage them in place

Gall removal: Cutting galls off vine trunks doesn't eliminate A. vitis from the vine -- the pathogen is systemic in infected vines. Gall removal can temporarily reduce visual symptoms but typically results in gall regrowth. In some cases, surgically removing galls while cutting back to clean wood below the gall achieves longer-term symptom suppression, but this requires clean cuts well below the discolored or galled zone.

Replanting decisions: When crown gall incidence in a block exceeds 20-25% of vines, the economic impact on block production typically justifies replanting rather than managing in place. Document incidence trends over several seasons before making replanting decisions. VitiScribe's block-level scouting history lets you track incidence per block per season and see whether it's stable, spreading slowly, or accelerating.

Record Keeping for Crown Gall Management

Because crown gall management is a multi-year endeavor (infections established years ago, disease spreading slowly, replanting decisions made based on multi-season trends), your documentation needs to capture:

Annual incidence surveys: number of affected vines per block, mapped by location within block where possible
Severity classification: percentage of trunk galled, estimated vascular impact
Cold weather events with minimum temperatures by block
Tool disinfection practices during pruning in affected blocks
Replanting decisions and dates

The correlation between cold events and subsequent crown gall incidence is one of the more valuable insights that multi-season documentation delivers. When you can show that your eastern Riesling block had its highest crown gall emergence 2 seasons after the 2019 cold event, you can plan for similar monitoring and management response in future cold years. See how VitiScribe pillar IPM guides connect to block-level records.

Frequently Asked Questions

How do I identify crown gall in my vineyard?

Crown gall produces irregular, tumor-like galls at wound sites on vine trunks, graft unions, and cordon surfaces. Early galls are soft, light brown, and often located at or near the soil line or at the graft union. Mature galls are larger, darker, and have rough surfaces with a hard exterior. In cross-section, gall tissue is disorganized without the normal wood structure of healthy vine tissue. Location is important -- crown gall galls appear on external vine surfaces at wound sites, which distinguishes them from internal wood diseases like Eutypa (which show internal discoloration only in cross-section, without external galls).

How is crown gall spread between vineyard blocks?

The primary spread routes are infected nursery planting material (the most important long-distance route), contaminated pruning and grafting tools (short-distance within-vineyard spread), and to a lesser extent irrigation water and soil organisms. A. vitis is a systemic pathogen that persists in infected vine tissue indefinitely -- you can't remove it from an infected vine or the immediate soil around it. Preventing introduction through certified planting material and managing tool disinfection are your primary spread-prevention tools.

What management options exist for crown gall in vineyard IPM?

For established infections, there's no registered bactericide. Management focuses on: minimizing additional wounds in infected blocks; disinfecting pruning tools between vines in high-risk areas; removing and replacing severely galled vines (incidence over 20-25%); and managing winter freeze risk to reduce the primary crown gall trigger. For new plantings, Agrobacterium radiobacter K84 (Norbac 84C) root dip at planting provides biological control against susceptible A. vitis strains. In all cases, document incidence annually by block to track spread trends and support replanting timing decisions.

Should crown gall incidence data be shared with winery buyers or appellation programs that review vineyard records?

Yes, when requested as part of a vineyard health documentation package. Winery buyers and some appellation sustainability programs are increasingly asking for multi-year vine health data that includes disease incidence records. Crown gall incidence data, alongside the management response you've taken -- tool disinfection practices, vine replacement program, nursery sourcing documentation -- tells a story of active management. A block with 15% crown gall incidence that you're actively monitoring and managing with a documented replacement program is a different conversation than a block where incidence has never been recorded. VitiScribe's block scouting records maintain the annual incidence data in a format that can be exported for buyer or certifier review.

How do I document pruning tool disinfection for crown gall management in my spray and IPM records?

Pruning tool disinfection isn't a pesticide application and doesn't generate a DPR record, but it belongs in your IPM records as a cultural management practice. Log it as a block activity in VitiScribe with the date, block, disinfectant used (alcohol or bleach solution), and whether it was applied between every vine or between rows. For sustainable certification audits, this type of documented non-chemical IPM practice -- showing that you actively manage infection spread through equipment sanitation -- supports the IPM-based management narrative that certification programs require. If tool disinfection was used as a response to a new crown gall finding in a block, note that connection in the activity record so the rationale is preserved with the documentation.

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Sources

UC Cooperative Extension Viticulture
American Vineyard Foundation
American Society for Enology and Viticulture (ASEV)
Washington State Department of Agriculture (WSDA)
Oregon Department of Agriculture (ODA)

Get Started with VitiScribe

Crown gall management is a multi-season documentation challenge: incidence data collected today becomes the basis for replanting decisions three years from now, and cold event records from this winter predict where new crown gall will appear in your blocks in 2027. VitiScribe's block-level scouting records maintain that longitudinal data in a system where it's searchable, exportable, and connected to your spray log and IPM records. Try VitiScribe free and log your first annual crown gall incidence survey to start building the block history your management decisions require.