Canker disease in plants occurs in many species of trees, shrubs, and ornamental plants and is a very common and harmful condition. It creates ugly damage and, without treatment, can even cause branch dieback, stunted growth, or plant death.
In this guide, we’ll see what triggers canker in plants and what kinds of plant canker symptoms should be identified, as well as the most effective measures for preventing and curing this disease. We’ll also clarify the difference between the bacterial vs fungal canker, so that you can choose an appropriate treatment for your trees.
Canker disease in plants is localized areas of dead tissue normally seen on the stems, branches, or trunks. These infected regions are usually concave, discolored stains, and they may have bark that is cracked or oozing. The disease is caused by different types of pathogens, fungi, and bacteria that enter plant tissue through wounds or weak points.
Canker is not restricted to a single kind of plant. It is even present in fruit trees (apples, peaches), ornamental trees (dogwoods or willows), and shrubs (roses, viburnums). When the disease penetrates the plant, it begins to eliminate healthy cells by creating scars or dead spots that interfere with the plant’s growth.
If you've ever found yourself pondering why plants canker, the reason is typically a combination of infection and environmental stress. Typically, canker infections get into plants that have already suffered some sort of physical trauma, drought, cold, or bad pruning. When the outer bark or skin of the plant cracks, it provides an opening for bacteria or fungal spores to move in and start growing.
Although certain cankers favor cold environments, others thrive in warmer, humid environments. Furthermore, certain species of trees are more prone than others to being attacked by canker. For example, bacterial canker commonly invades peach trees, while fungal canker infests pine trees.
The signs of canker in plants can vary based on the pathogen species and type. That said, if you suspect that your plant might be ill, there are several general signs to watch out for.
Sunken, cracked areas on the bark are one of the first indications of canker disease on plants. Eventually, these areas get bigger and appear lighter or darker than the normal bark surrounding them. On rare occasions, particularly on fruit trees, sap or resin may exude from the wound.
Also, you notice that the bark covering the affected area peels off or comes off easily. The girdled look of the affected branch shows that the disease has gone all the way around it, cutting off the flow of nutrients and water.
You might observe drooping, yellowing, or browning of the leaves along with injury to the bark, particularly on the branches closest to the canker. Those branches can eventually die back completely as the disease progresses. Extensive sections of the tree or plant can begin to die in extreme cases.
On the canker surface, certain plants can exhibit fungal fruiting bodies or small black spots. These fruiting bodies are reproductive organs that spread the disease to adjacent areas by releasing spores.
Since bacterial and fungal cankers have different management and treatment methods, it is important to understand the variations between the two. While both types may share the same symptoms, they are different in behavior and respond differently to treatment.
Disease-causing bacteria enter plants using natural injuries or openings, causing bacterial canker. Bacterial canker is more common in wet, moist environments and will often produce a sticky, oozing sap. Prunus fruits, such as cherries and plums, are especially susceptible to bacterial infection. Bacterial cankers, having formed, tend to be more challenging to control and develop at a faster pace.
Conversely, certain fungal species living in soil, dead vegetation, or even on healthy-looking plants can cause fungal canker. Spores from such a fungus may be spread by insects, winds, rains, or contaminated instruments. Even though fungal cankers tend to develop slowly, if left untreated, they can become recalcitrant and difficult to eliminate.
Lab work or close inspection by a gardening expert or arborist could be required to ascertain if your plant has a bacterial or fungal disease.
The best mode of treatment of canker disease depends on the type of involved pathogen as well as on the severity of the disease. In most instances, the disease might be arrested by excision of the damaged tissue as early as it becomes known.
Prune out the infected branches as one of the best methods to manage canker disease. Cut several inches below the infected area using a saw or clean, sharp pruning shears. You stop the spread of the disease, make sure you sanitize your tools with rubbing alcohol or a bleach solution between cuts.
Pruning will be more successful if the weather is dry and the fungus or bacteria are less active, reducing further spread.
Most chemical treatments for bacterial canker are only partially effective. Copper-based bactericides and fungicides applied during dormant periods or immediately after pruning will aid in the prevention of the spread of bacterial canker. Fungicides can also be applied as a preventative on high-risk trees, but it is most effective when applied early.
Sadly, there is no known cure for severe canker disease. It might be required to cut out and replace the whole plant if the disease has gone too far.
Preventing canker in the first instance is the ideal way to cure it. Getting the right growing conditions is important, as healthy plants are considerably more resistant to disease.
Plants must always be treated gently, particularly when they are relocated or pruned. Avoid heavy equipment or lawn movers that can damage the bark. Covering trunks in winter and watering deeply in times of drought to reduce drought stress may help shield your trees from frost injury.
Bushes and trees must be pruned in dry weather; do not prune during wet or humid weather. Cut always at an angle and never leave stubs, as this could be breeding germs or fungus. During late winter, when the pathogens are dormant, remove any affected tissues if your tree has already progressed to canker.
Take out dead leaves, dead branches, and other plant waste to maintain your landscape clean. These products often contain germs that lead to illness. Inspect your plants regularly for signs of disease, especially during the growing season.
Canker disease of plants may be alarming, but with appropriate knowledge and care, it is possible to control it. Knowing how to identify plant canker symptoms and what causes canker is the first step in forestalling the disease from spreading. Either bacterial or fungal canker, early pruning and regular hygiene practices will go a long way in protecting your plants. There may not be any quick fix, but learning how to remedy canker disease and planting habits can keep your garden healthy and beautiful for years.
This content was created by AI