Getting Rid of Crown Gall on Your Trees and Shrub

Milosh Potikj | October 20, 2023 | 8 MIN READ

If you're a home gardener, landscaper, or horticulturist looking for ways to get rid of crown gall--those unsightly swellings and bumps that can appear on the stems or roots of trees and shrubs--then you've come to the right place! In this blog post, we'll provide practical advice on identifying and treating crown gall in your trees and shrubs.

We'll discuss signs to look for, natural remedies you can apply at home, and strategies if all else fails. So, whatever issues you may be experiencing with your trees or shrubs due to crown gall infestation, rest assured that help is here!

Identifying Crown Gall on Your Trees and Shrubs

First things first, let's talk about identifying crown gall. Identifying this condition early is crucial to prevent further damage to your plants. Crown gall is a plant disease caused by the bacterium Agrobacterium tumefaciens, which results in large, tumor-like growths on the stem, roots, and sometimes leaves of the affected plant.

Visible Signs of Crown Gall

Identifying crown gall can be a challenge due to the variety of symptoms. However, there are several common visible signs to look out for:

  • Initial appearance of small outgrowths on the stem or root of the plant, gradually growing into larger, rough, tumor-like structures.

  • The size of the galls can range from the size of a pea to several inches in diameter.

  • The color of the galls can vary from light brown to dark brown or even black as they mature and harden.

  • Galls can also form beneath the soil on the plant's root system, which may be harder to detect.

  • Other signs may include stunted growth or yellowing of leaves, often resulting from the gall disrupting the plant's normal nutrient and water movement.

Crown galls are often easy to spot as they present rough, woody, tumor-like growths on the plant. They can range from tiny bumps to large round galls, even reaching up to a foot in diameter in severe cases. These galls are initially light-colored, often taking on a dark brown or black hue as they age.

Commonly Affected Plants

Before we delve into the prevention and treatment options for crown gall, let's familiarize ourselves with the types of plants most susceptible to this bacterial disease. Understanding which plants are more prone to this disease can help you take preventive measures and ensure early detection.

  • Woody ornamentals often become victims of this bacterial disease.

  • Fruit trees, especially apple and plum trees, are commonly affected.

  • Certain shrubs and vines are susceptible, including but not limited to roses, raspberries, and euonymus shrubs.

  • Other plants, such as willow trees, aspens, and herbaceous plants, may also be affected.

It's crucial to understand that susceptibility can depend on many factors, including the specific species and cultivar of the plant and environmental conditions.

Read More: Root Rot in Orchids

Natural Remedies for Crown Gall

Natural Remedies for Crown Gall

Now that we've identified the signs of crown gall and the plants most at risk, it's time to discuss remedies you can apply at home. Fortunately, there are several natural ways to combat this bacterial disease, helping to protect your beloved plants and keep your garden thriving. Let's delve into these natural remedies for crown gall.

Using Beneficial Bacteria

One of the most effective natural remedies to combat crown gall is the use of beneficial bacteria, specifically a strain of Agrobacterium radiobacter (K-84 or K-1026). This bacterium is a natural enemy of the crown gall, causing Agrobacterium tumefaciens. When introduced to the soil or directly onto the plant, it works by out-competing the harmful bacteria for resources, essentially starving them and preventing them from infecting the plant.

This method is particularly effective as a preventative measure. It's worth noting that this treatment does not harm the plant or alter its growth, making it a safe and natural way to protect your plants from crown gall.

Homemade Treatments

Apart from using beneficial bacteria, there are several homemade treatments that can be used to manage crown gall. These remedies are simple and cost-effective and can be whipped up with items you likely already have around your home.

  • Baking Soda Solution: A baking soda solution can help control the spread of the bacteria. Mix 1 tablespoon of baking soda with 1 liter of water and spray it on the affected area. Repeat this process weekly.

  • Hydrogen Peroxide: Hydrogen peroxide can be effective at killing the bacteria that cause crown gall. Mix equal parts 3% hydrogen peroxide and water and apply it to the galls with a spray bottle. Be sure to avoid any healthy parts of the plant.

  • Pruning: Removing the infected part of the plant can also help control the disease. Make sure to sterilize your pruning tools before and after use to avoid spreading the bacteria to other plants.

  • Heat Treatment: Exposing the infected plant to a high temperature can kill the bacteria. This can be done by soaking seeds or bulbs in hot water (around 50 degrees Celsius) for 15-20 minutes.

Remember, these homemade remedies are treatments and should not replace good gardening habits such as regular inspection of plants, proper sanitization of tools, and the planting of disease-resistant varieties.

Advanced Crown Gall Treatment

Advanced Crown Gall Treatment

As you continue on your gardening journey, it is essential to arm yourself with more robust and advanced treatments for crown gall. These methods are particularly useful when the disease has progressed significantly, and natural remedies are not enough. So, let's tackle these advanced strategies together to ensure the health and longevity of your plants.

  • Professional Remediation

For advanced cases of crown gall or large-scale infestations, you may need to seek help from a professional plant pathologist or a licensed pest control advisor. They can provide more comprehensive treatment plans, potentially involving commercially available bactericides, specialized biocontrol agents, or soil fumigation. It's important to note that professionals should manage these treatments, as they involve substances that can be harmful if not used correctly.

In addition, professional remediation may include removing and safely disposing of severely affected plants to prevent the spread of the disease. Remember, professional help is a valuable resource in maintaining the health and beauty of your garden when dealing with stubborn or pervasive plant diseases like crown gall.

  • When to Consider Replacement of the Plant

In some instances, despite all efforts, the plant may not recover from the crown gall infection, or the damage may be too extensive for effective treatment. This is usually the case when the galls are large, numerous, or located near the base of the stem or root crown, causing significant interference with the plant's vital functions. In such situations, it may be more beneficial to consider replacing the affected plant.

However, before removing the plant, it is crucial to consult with a plant pathologist or a professional gardener who can determine that replacement is the best course of action. If replacement is advised, remove the entire plant carefully, ensuring no remnants of the root system remain in the soil, as these can potentially harbor the bacteria.

When replacing the plant, consider using disease-resistant varieties and ensure the new plant is free from crown gall. Buying from a reputable nursery can help guarantee this. Always remember to properly prepare the soil before planting, and consider using beneficial bacteria as a preventative measure to protect the new plant.

Replacing an affected plant might seem drastic, but sometimes, it's the best choice to maintain the overall health of your garden. It's a reminder that gardening sometimes involves tough decisions, but each one contributes to the ongoing journey of learning and growth.

Learn More: Damping Off Disease

Preventing Crown Gall Infestations

Preventing Crown Gall Infestations

While protecting our plants from diseases is crucial, prevention is always better than cure. In this section, we will explore effective strategies to prevent crown gall infestations from invading your beautiful garden in the first place. These tips and methods will help you maintain a healthy and vibrant garden, free from the worry of crown gall.

Proper Plant Care

An essential part of preventing crown gall is establishing proper plant care practices. These practices help maintain overall plant health, making your plants less susceptible to disease. Here are some crucial points to consider:

  • Choose Disease-Resistant Varieties: Some species and varieties of plants are naturally less susceptible to crown gall. Do some research or ask at your local nursery to find out which ones these are.

  • Inspect New Plants: Always check new plants for signs of crown gall before bringing them into your garden. This can help prevent accidental introduction of the disease.

  • Maintain Healthy Soil: Healthy soil is key to healthy plants. Ensure your soil has the essential nutrients and is well-drained to prevent water-logging, which can stress plants and make them more susceptible to disease.

  • Use Clean Tools: Always clean your gardening tools before and after use. This can prevent the crown gall bacterium from spreading from one plant to another.

  • Avoid Injury to Plants: Injuries to plants can provide entry points for the crown gall bacterium. Be careful when pruning or handling your plants to avoid unnecessary damage.

  • Monitor Plant Health: Regularly monitor your plants for signs of disease. Early detection and treatment of crown gall can help prevent its spread.

Regular Inspections and Early Detection

Regular inspections and early detection of crown galls are pivotal in maintaining a healthy garden. Start by developing a routine plant check-up, looking closely at the stems, roots, and leaf undersides. Watch for the telltale signs of this disease, such as abnormal growths or swellings. Remember, these galls can range in size and appear as light-colored tumorous growths, becoming darker as they mature.

If you spot anything unusual, isolate the affected plant immediately to prevent the bacteria from spreading. The sooner you identify and address the issue, the better your chances of controlling the disease and minimizing its impact on your garden. Never underestimate the power of vigilance and early detection in preventing crown gall infestations.

Frequently Asked Questions

How do you treat crown gall on a tree?

Treating crown gall on a tree requires a combination of proper care practices and targeted treatments. Start by pruning off the infected branches with sterilized pruning tools, and apply a suitable bactericide to the pruned areas. It's recommended to seek advice from a professional arborist for severe cases.

How do you remove crown galls?

Removing crown galls involves carefully pruning them off the plant with properly sterilized tools. Ensure the cut is clean and no gall material remains attached to the plant to prevent reinfection.

How do you control crown gall in plants?

Controlling crown gall in plants involves a mixture of preventative and reactive measures. Ensuring healthy soil conditions and caring for plant wounds can reduce the chances of infection. In established cases, the removal and disposal of affected plants and chemical treatments can help manage the disease.

How do you stop a crown gall from spreading?

To stop crown gall from spreading, it's vital to adopt hygiene practices like cleaning garden tools before and after use, which helps minimize bacterial transfer from an infected plant to a healthy one. Regular monitoring of plants and quick isolation of infected ones are also key strategies in preventing the spread of this disease. Lastly, proper disposal of infected plant material is essential to prevent bacteria in the soil from re-infecting new plants.


Gardening is both a joy and a responsibility. Managing diseases like crown gall may present a challenge, but you can create and maintain a healthy, thriving garden with knowledge and the right practices. Remember that prevention is the most effective strategy. You can keep your garden free from crown gall by choosing disease-resistant plant varieties, maintaining healthy soil conditions, using clean tools, and regularly inspecting your plants.

And even if your plants become infected, early detection and decisive action can keep the impact to a minimum. So, roll up your sleeves and embrace the wonderful gardening journey, knowing that overcoming every challenge is a step towards a more vibrant and resilient garden.


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