May 15, 2025 and

Crown Gall in Grapevines – Early Symptoms and Management.

What is Crown Gall?

Figure 1. Early symptoms. Young soft galls developing on the graft union during early spring (L) and cracking of bark by growing crown galls (C and R).

Crown gall is a serious disease affecting grapevines, particularly in cool-climate viticulture. It is caused by the soil- and plant-borne bacterium Agrobacterium vitis (A. vitis). This pathogen induces tumor-like growths (galls) that disrupt the grapevine’s vascular system, reducing the flow of water and nutrients from roots to shoots. If left unmanaged, crown gall can stunt vine growth and eventually kill the plant.

Diseases Symptoms

The earliest and most distinctive symptoms are abnormal, soft, whitish swellings (see Figure 1, Left). As these galls grow, they cause the bark to crack and peel due to pressure from underneath (Figure 1, Center and Right). Galls can initially be mistaken for benign growth, and therefore, detection requires careful inspection.

Figure 2. Crown gall on the graft union and trunk of the grapevine.

As the disease progresses, galls may become woody, rough, and brown, growing to several inches in diameter (Figure 2). They most often appear at the graft union or sites of mechanical injury on the lower trunk. The graft union is especially susceptible due to: (i) its irregular shape, which is prone to cracking, and (ii) potential contamination by A. vitis during the grafting process. Galls may also form on cordons and canes. Early scouting and removal of affected trunks can help limit the spread of infection. If the gall encircles the vine’s vascular system, the entire plant may collapse and especially in young vines, which have thinner trunks.

Another indicator of severe infection is the emergence of multiple new suckers from the vine base (Figure 1, Left). Additionally, leaves of affected vines may show green wilting and reddening due to restricted water and nutrient flow (Figure 3). However, similar symptoms can also result from viruses or nutrient deficiencies, making diagnosis challenging. In such cases, inspect the trunk visually for physical signs of gall formation or vascular disruption.

 

Why does wounding cause gall formation?

Figure 3. Leaf of crown gall-affected grapevine showing green wilting and reddening.

Wounding is a key point of infection in crown gall development. In early spring, grapevines attempt to heal sites of winter injury by producing callus tissue. These masses of undifferentiated cells with soft cell walls are particularly vulnerable to infection. A. vitis, which may already be present in the vine, exploits these wounds to inject its DNA into the callus cells. This bacterial DNA contains a tumor-inducing gene that integrates into the plant’s genome, leading to uncontrolled cell division, resulting in the characteristic gall.

Management of Crown Gall

An integrated pest management (IPM) approach is essential for effective crown gall control. Strategies include:

1, Avoidance
Site selection is the best decision to avoid cold injury. Avoid planting in low-lying areas where cold air settles. Gentle slopes are preferable for air drainage but beware that cold air may still collect at the lower end of a slope. Avoid planting in such spots unless you have excellent air drainage practices.

Figure 4. Grapevine in a year after hilling and damaging winter. Notice the graft union and trunk a few inches above it, unaffected by winter damage due to hilling-up, while the unprotected trunk shows crown gall.

2. Exclusion
Start with clean, certified planting material to reduce the chance of introducing A. vitis into your vineyard. Ideally, use 2010 Protocol-certified stock, which is propagated using advanced screening techniques to minimize bacterial contamination.

3. Resistance
Different grapevine species vary in susceptibility. Vitis vinifera cultivars are generally more susceptible. Hybrids and some vinifera varieties show moderate tolerance. Native species and certain hybrids tend to have better resistance. Consider planting more resistant varieties in areas prone to cold injury.

4. Protection
Hilling up soil around the base of vines during winter is highly effective. The soil acts as insulation, protecting the graft union and lower trunk. While this won’t shield unburied parts of the vine, it can preserve enough tissue to allow regrowth from protected suckers (Figure 4). Training these suckers as new trunks and using multiple trunks per vine can reduce the risk of total vine loss. For detailed guidance, refer to Rutgers NJAES Factsheet FS1264.

5. Eradication
Remove and destroy infected vine sections (Figure 5). This is the most effective post-infection strategy. Scout during early spring or winter pruning. Any removed vine parts should be taken out of the vineyard entirely. If removing an entire vine, extract it with the root system, as A. vitis can persist in root debris for years.

6. Chemical Control Options

Figure 5. New trunks and cordons were developed after removing the old, infected cordon.

A few commercial treatments are available, including:

  • Galltrol-A (AgBioChem, Inc., Provo, UT)
  • Gallex (AgBioChem, Inc., Provo, UT)
  • Copper-based compounds
  • Antibiotics

However, their effectiveness varies. Once the bacteria establish themselves systemically, eradication becomes extremely difficult. Always follow label instructions and integrate chemical treatments with cultural practices for best results.

References
Burr T. and Martinson T. 2015. Start Clean, Stay Clean Grape Crown Gall. National Clean Plant Network. Factsheet.

Moyer M. 2013. Grapevine Crown Gall. – Disease Management White Paper. Wine.wsu.edu/research-extension/

Gohil H., Nitzsche P., and Ward D. 2017. Hilling up to Prevent Winter Injuries in Vineyard. Rutgers NJAES Factsheet 1264. https://njaes.rutgers.edu/fs1264/

Todaro T. and Longstroth M. Managing Grapevine Crown Gall. Michigan State University Extension.

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May 8, 2025

South Jersey Wine Grape Twilight

When: May 20 (Tue) 5:00 PM
Where: Autumn Lake Winery: 870 W Malaga Rd, Williamstown, NJ 08094

Pesticide Credits: CORE; PP2; 1A; 10

PROGRAM

Welcome and Updates
Hemant Gohil, Gloucester County Extension Agent, Rutgers NJAES
Mark Hernandez, Owner, Autumn Lake Winery

Field Observations from the Wine Grape IPM Pilot Program
Janine Spies, Statewide Fruit IPM Program Leader, Rutgers NJAES.

2025 Recommendations for Disease Management
Peter Oudemans, Extension Specialist, Small Fruit Pathology, Rutgers NJAES.

Record Keeping Update for 2025
George Hamilton, Extension Specialist in Pest Management, Rutgers NJAES.

Grape Berry Moth in the Vineyard
Anne Nielsen, Extension Specialist in Fruit Entomology, Rutgers NJAES.

Crown Gall – Early Symptoms and Management
Hemant Gohil, Extension Agent, RCE of Gloucester County.

Grape Nutrition Update. 
Gary Pavlis, Extension Agent, RCE of Atlantic County.

Pesticide recertification credits and adjourn.

Light fare will be provided. If you plan to attend, please email Joan Medany at jmedany@co.gloucester.nj.us or call 856-224-8030. For additional assistance, please get in touch with Hemant Gohil at 856-224-8029 before the meeting.

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April 23, 2025

South Jersey Tree Fruit Twilight Meeting – I

When: May 7th (Wed) @ 6:00 pm
Where: Gloucester County Govt. Services Building, 1200 N. Delsea Drive,  Clayton, NJ 08312

Pesticide credits – 4 each PP2, 1A, and 10

6:00 pm       Light Fare (Pizza, Donuts, and Coffee)

6:15 pm        Welcome and updates.
Hemant Gohil, Gloucester County Agricultural Agent, Rutgers NJAES

Peach Quality and Quality Standards
Daniel Ward, Extension Specialist, Pomology, Rutgers NJAES

Field Observations from the IPM Program
Janine Spies, Statewide Fruit IPM Agent, Rutgers NJAES.

Tree Fruit Disease Update
Kaitlin Quinn, Fruit IPM Program Associate, Rutgers NJAES.

Insect-Pest Management in the Orchard.
Anne Nielsen, Extension Specialist, Fruit Entomology, Rutgers NJAES         

Managing the Nitrogen Cycle, N Sources, Timing, Rates, and Placement
Joseph Heckman, Extension Specialist, Soil Fertility, Rutgers NJAES

Farm Fresh Marketing: Harnessing Customer Photos, Posts, and Praise
Claudia Gill Arroyo, Cape May County Extension Agent, Rutgers NJAES

8:50 pm        Pesticide recertification credits application.
Meeting Adjourn

Light fare will be provided. If you plan to attend, please call Joan Medany at jmedany@co.gloucester.nj.us or 856-224-8030. If you have any questions, please contact Hemant Gohil at 856-224-8029 before the meeting.

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April 5, 2025

High Risk of Frost Damage in Peach Orchards

The below-freezing temperatures on Tuesday (4/8) and Wednesday (8/9) will likely invite frost damage to peach orchards in New Jersey. In several parts of New Jersey, peach flower buds are in the bud swell to the petal fall stage.

Figure 1. Peach bud development stages and corresponding critical temperatures. Adapted from MSU Fruit Extension. Photos by H. Gohil

Bloom progression in southern New Jersey indicates that except for very few delayed blooming varieties such as ‘Gloria’ and “Scarlet Rose’ most varieties will be in the bloom or post-bloom, next week. These are the most vulnerable stages to frost damage (Figure 1). Often, the cause is a few hours below the injury threshold temperature for the developing buds. Monitoring the growth stage and weather conditions will help in determining the actual threat of frost damage and whether to start a frost protection system.

Monitor the orchard temperature. Frost can occur when the ambient temperature dips below freezing (32°F). The hourly falling rate and the lowest forecasted temperature should also be monitored.  Because the threshold temperature for each bud development stage is different, and a slight temperature difference can make a difference between frost damage and no damage, it is essential to know the precise temperature. In most cases, the orchard temperature will not be the same as forecasted or reported by the weather channels because the weather station could be farther away than the orchard location. Remember that the nighttime temperatures often dip below the predicted temperatures. It is crucial to have a thermometer in the orchard. Even the data from the nearby weather station could be unreliable. Also, frost alarm systems can give precise temperatures in the orchard and send warning messages to your mobile phone at a set temperature. Some systems can also report wet-bulb temperature, essential when using overhead irrigation for frost protection (Figure 2).

Monitor the bud development stage for each variety block, starting from bud swell. Critical temperatures have been researched and calculated for each bud development stage. For example, at 25°F, a peach orchard in full bloom can expect up to 90% crop loss, but at the first pink stage, it will suffer only marginal loss (Figure 1).

The critical temperature for damage at a particular bud stage may vary by 4-5°F depending on temperatures during the previous few days before the cold event.

Figure 2. Weather Station with in-built frost alarm system in Peach Orchard, Medford, Southern NJ.

Therefore, growers should use caution when using these published critical temperatures for active frost protection methods. Also, knowing the bud development stage for all varieties in the orchard will allow you to prioritize varieties or blocks that need frost protection.

Cloud coverage:  Clear skies enhance radiative heat loss into the sky, which results in lower temperatures than when there is cloud cover, which can trap radiant energy from the ground.

Wind Speed: Wind increases the rate of heat loss from the ground and plant tissues. Low speed allows the formation of the inversion layer. Most frost protection methods will have reduced efficiency at wind speeds above 10 mph. Fire or heat application-based methods are less effective at wind speeds below five mph.

The frost protection method should only be employed after determining the actual risk of frost and considering the cost-benefit analysis. The articles below have information on passive and active frost protection methods.

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April 4, 2025

NJ DEP issues Open Burn Permit from April 6 through April 12, 2025

To Agriculture and Agribusiness Representatives:

The New Jersey Department of Environmental Protection (DEP) is issuing this notice concerning open burning due to colder spring overnight temperatures presently forecasted for areas of New Jersey from April 6 (Sun), through April 12 (Sat), 2025, which could adversely affect fruit, vegetable, and floriculture crops in bloom or near bloom around the state. The DEP intends to exercise its authority and discretion under the Air Pollution Control Code, N.J.A.C. 7:27, et seq., and other applicable authorities to permit the following procedure for open burning or the use of smudge pots to assist farmers in protecting their crops in low temperatures. These cold events could adversely affect some of the fruit, vegetable, and floriculture crops. 

Note: The NJDEP and New Jersey Forest Fire Service caution all farmers and agriculture businesses with respect to the use of open burning in high wind velocity conditions. Please take note that farmers are encouraged to utilize smudge pots is warming as necessary during higher wind conditions. Use of open burning when wind velocity is greater than 5mph is strictly prohibited, may contribute to wildfire risk, and can carry significant penalties.

For the Burn Permit Application form, please see: https://www.state.nj.us/dep/parksandforests/fire/docs/ag-permit.pdf

The DEP intends to exercise its authority and discretion under the Air Pollution Control Code, N.J.A.C. 7:27, et seq., and other applicable authorities to permit the following procedure for open burning or the use of smudge pots to assist farmers in protecting their crops in low temperatures. Procedures for Open Burning and the Use of Smudge Pots Pertaining to New Jersey Fruit, Vegetables, and Floriculture

  • Facilities that believe they will conduct open burning or use smudge pots must provide notice to the DEP 24-hour Communications Center at 1-877- WARN DEP (1-877-927-6337) prior to the use of either technique. • Facilities should notify DEP if they believe they may need to use either technique. • Where DEP cannot be notified in advance, a facility must notify DEP the following morning no later than 9:00 a.m. • The following information must be provided to DEP upon each notification:
  1. Name of the individual deciding to conduct the open burning or use of smudge pots.
  2. Name of the farm or facility
  3. Actual street address of the facility on which either technique will be used.
  4. Contact person and telephone number at the facility.
  5. Predicted temperature (in F) at facility anticipated when the technique will be used.
  6. Predicted wind speed at facility anticipated when the technique will be used.
  7. Predicted hours of open burning or use of smudge pots
  8. Predicted material to be used for open burning or use of smudge pots.
  • Upon completion of the open burning or the use of smudge pots, the facility must provide the following information within 2 business days to the DEP 24-hour Communication Center at 1877-WARN DEP (1-877-927-6337):
  1. The DEP Communications Center incident number
  2. Ambient orchard(s) temperature (in F) at the time the technique was used.
  3. Actual wind speed at the orchard(s) location at the time the technique was used.
  4. A statement that all restrictions in the open burning or use of smudge pots were followed. The restrictions are noted below.

RESTRICTIONS

  • NO OPEN BURNING WILL BE PERMITTED UNLESS: 1. The temperature within the orchard area is at or below the critical temperature for the bud stage. The attached report lists the critical temperatures for New Jersey crops. -AND 2. The wind velocity is less than 5 miles per hour.
  • Authorized open burning material may consist only of either the following materials: clean scrap lumber (untreated), felled trees, prunings, hedgerows or firewood.
  • ABSOLUTELY NO refuse, trade waste, tires, garbage, or other solid waste may be added to the authorized open burning material. Introduction of any unauthorized material into an authorized open burn is a violation of environmental laws and may carry significant penalties.
  • Smudge pots are only permitted when the temperature within the orchard area is at or below the critical temperature for the bud stage (wind velocity restriction does not apply).
  • Smudge pots must be fueled only with either kerosene or No. 2 fuel oil.
  • Failure to abide by these provisions and restrictions may result in enforcement action.

 

 

Filed Under: Blueberry, Cranberry, Fruit, Landscape, Nursery, & Turf, Nursery, Strawberry, Tree Fruit, vegetable, Wine Grape Tagged With: , , , ,
March 26, 2025 , , and

Preparing Orchards Against the Frost – Low Tech Strategies

Frost is common in the northeastern US. However, frost events during bloom, specifically in orchard crops, can be economically devastating. Often, the cause is a few hours below the injury threshold temperature for the developing buds, as cooler nights result in the rapid loss of thermal energy. Several passive or low-tech strategies can help maintain a slightly higher orchard floor temperature and potentially prevent substantial crop loss.

Site selection is the most effective frost protection method. When planning a new orchard, selecting a site with proper cold air drainage is the most valuable decision a grower can make and enjoy the rewards for many years. Cold air drainage is essential, so avoid buying a site or planting trees on the site that accumulate cold air. Also, identify areas where the cold air moves in and out. When possible, plant early blooming varieties in the least frost-prone areas and plant delayed and or extended bloom varieties in frost-prone areas.

Table 1. Relative temperature differences are influenced by orchard floor conditions (Courtesy, Robert Crassweller, PSU).

Do not invite the frost with excess vegetation and ground cover. The management of weeds along the row and sod between the rows will influence orchard temperatures. The bare ground will absorb more heat during the day and release more heat at night than soil covered in vegetation (Table 1). During the day, 45-50% of solar radiation gets reflected or absorbed by the atmosphere, and the earth absorbs the remaining 50-55%. Vegetation reduces this heat transfer to the soil because it reflects light before it can reach the soil surface. Removing tall weeds and windbreaks along the edges of orchards will also help improve airflow and limit the accumulation of cold air pockets in some areas of the orchard. This can be particularly important during spring bloom when just a few more degrees can make the difference between killing the flowers or not!

Extremely low grass cutting: Maintaining sod between the rows at a minimum height by frequently mowing will help with frost protection. Similarly, keeping the rows weed-free by using postemergence herbicides to kill emerged weeds and removing weed residues from the previous season will maximize the warming of the soil by solar energy during the day. Maintaining weed-free rows should also be considered by applying residual herbicides in the fall. Depending on herbicides applied in the fall, this will prevent or reduce weed emergence in early spring and give you more flexibility for applying your residual and postemergence herbicides in spring. 

The cold air drain machine has a fan that pulls cold air from the surrounding ground and pushes it into the sky. This is effective in a lower section of the orchard or the end of the vineyard where the cold air drains due to a slight slope. Placing the machine in the middle of the orchard may prove ineffective as the pulled cold air could settle back into the orchard unless there is a low inversion layer to mix with warmer air. Using the cold air drain machine can enhance the effectiveness of low grass cutting. The machine costs around $15,000, and its operating cost is much less than other active frost protection methods.

Wet soil slows the release of thermal energy on frost night. However, the soil profile must be thoroughly wet. This can be achieved by irrigating the soil to field capacity (maximum water holding capacity of that soil). Also, the temperature must be warmer during the preceding days to pack sufficient heat into the soil. Sandy soils store less energy than loamy soils because there is more air space between soil particles than loamy soils. Heavier soils may require more than 8–10 hours of irrigation to reach field capacity.

Delayed pruning delays bud development, which helps avoid damage from early spring frosts. Years of observation in commercial orchards in the northeast indicate that more buds survive after a frost event, specifically in peaches, if the pruning is delayed. Often, large farm operations begin pruning early in the dormant season due to labor availability and time constraints. In such cases, avoid pruning upper branches until the risk of a late freeze has passed. Also, avoid hard blossom thinning on peaches on lower branches or blossom thinning altogether. Instead, focus only on fruit thinning, which can serve as insurance against crop loss. Remember that any available crop will likely command a good price in frost years.

Combining the above methods can have a cumulative effect on overall frost protection in the orchard. Keeping trees healthy with proper nutrient and pest management is also important. Healthy trees may still lose a crop but are more likely to survive the next season than poor vigor and diseased trees. The success of Frost Protection will also depend on understanding each method’s working principles and the combination of environmental factors necessitating its use. The bulletin https://njaes.rutgers.edu/e363/ explains what to monitor before a frost event and active frost protection methods such as irrigation, heat application, and air mixing.

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