Nothing strikes dread into the heart of a cherry tree owner like the sight of sap bleeding from the bark. This troubling condition, known as gummosis, can indicate serious issues that threaten the tree’s health. Understanding what causes oozing sap on cherry trees is key to resolving the problem.
What is Gummosis?
Gummosis refers to sap exuding from wounds or cankers on woody fruit trees like cherries, peaches, plums, apricots, and citrus The sap appears as globs, drips, or streaks on the bark. It often smells sour and feels gummy or sticky to the touch
Even though trees naturally leak some sap, too much oozing is a sign of a more serious problem. It’s the tree’s desperate attempt to compartmentalize damage or disease. But over time, cherry trees lose their strength when they lose too much sap.
Common Causes of Gummosis
There are several potential explanations when sap starts oozing from cherry bark
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Canker diseases – Fungal infections create sunken dead areas (cankers) that ooze sap. Common culprits are cytospora, valsa, and perennial canker. Frequency: 14
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Borers: Peachtree borers and other insects have larvae that tunnel under the bark and cause sap to flow. Sawdust-like frass near sap is a telltale sign. Frequency: 11.
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Extreme weather, bad soil, not enough water, and a lack of nutrients can all cause environmental stress, which can lead to gummosis. Frequency: 7.
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Damage from lawn mowers, string trimmers, frost cracks, and other physical wounds can cause sap to leak out as the tree tries to heal. Frequency: 12.
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Improper pruning – Cutting branches improperly allows disease entry, leading to canker development and gummosis. Frequency: 9
Catching gummosis early allows you to identify and address the cause before major harm occurs.
Dangers of Gummosis
While a minor sap leak here and there is no big deal, extensive gummosis weakens and threatens cherry trees in several ways:
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Structural instability – Cankers create weak areas prone to breaking, especially with heavy fruit loads.
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Nutrient loss – Oozing sap saps energy reserves needed for growth and production.
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Pest vulnerability – Sap and cankers attract insects and diseases.
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Reduced yields – Tree goes into survival mode, producing less fruit.
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Lower cold hardiness – Gummosis leaves trees more prone to winter damage.
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Spread of decay – Cankers expand, allowing rot to take hold.
Swift treatment of gummosis is required to avoid decline and death of affected cherry trees.
Solutions for Oozing Cherry Trees
If your cherry tree is bleeding sap, here are some corrective steps to take:
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Identify the cause – Look for cankers, insects, wounds, and other symptoms pointing to a source. Have a professional inspect if unsure.
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Improve growing conditions – Rule out environmental stressors like drought, extreme heat, or poor drainage.
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Apply fungicides – Protect healthy bark and spray cankers to prevent fungal spread.
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Use insecticides – Target borers and other pests attacking the wood.
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Prune out cankers – Cut 6 inches below and beyond visibly diseased bark. Sterilize tools between cuts.
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Protect wounds – Paint pruned areas and wrap injuries to prevent reinfection.
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Provide extra care – Mulch, fertilize, water, and prune properly to support recovery.
With diligent treatment guided by the sap’s clues, gummosis can be overcome and cherry trees returned to flush, abundant fruiting.
Identifying Cytospora Canker
The most notorious cause of gummosis on cherry trees is cytospora canker, a fungal disease. Some clues pointing to cytospora:
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Cankers form on scaffolds and main branches
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Dead bark is reddish-brown and sunken
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Oozing occurs early spring through fall
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Leaves wilt suddenly on affected branches
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Entire branches rapidly die back
Cytospora enters through bark injuries and pruned sites. It causes extensive gummosis, dieback, and decline when left unchecked. Vigilant pruning of diseased wood is required to save the tree.
Preventing Gummosis
While gummosis treatment is aimed at the cause, prevention focuses on minimizing risks:
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Choose disease-resistant varieties like ‘Montmorency’ or ‘Meteor’
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Prune judiciously in dry weather to avoid wounds
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Disinfect pruning tools between trees
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Allow proper spacing for air flow
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Maintain vigor with regular fertilization
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Irrigate during droughts to reduce stress
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Protect trunks from lawn damage
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Apply preventative fungicides and insecticides
With good cultural care and hygiene, you can stop gummosis before it ever starts!
When to Worry About Oozing Sap
Occasional sap leakage from small wounds isn’t necessarily alarming. But extensive gummosis, especially from cankers, requires rapid response.
See a professional if oozing can’t be explained, spreads aggressively, or if the cherry tree shows sudden decline. In severe cases, removal may be required to prevent infection of other trees.
While gummosis in cherry trees is always serious, solutions exist in most cases with prompt action. Identify the source and treat appropriately to preserve the tree and bountiful harvests to come.
How to treat gummosis in cherry trees
The best way to treat gummosis or bacterial canker in cherry trees is to remove it early on. When you remove it, you will remove the bacterial pathogen.
To remove bacterial canker on your cherry tree, prune off the diseased branch. Be sure to cut at least two inches (5 cm) before the canker appears on the branch as the pathogen may also be hidden inside the branch.
Once you remove the diseased wood, dispose of it in a sealed bag. Do not not put it in the compost, where bacterial canker can continue to spread.
After pruning out the diseased branches, disinfect your pruning tool with isopropyl alcohol and wipe it with a clean rag. This reduces the risk of spreading the pathogen to other trees.
If you let things go too far, the bacterial canker and gummosis will take over the tree. When there is gummosis all over the tree, in its trunk, branches and even roots, you will have to cut the tree down to stop the problem from spreading to other trees nearby.
Also, don’t plant another tree in the same spot because the pathogen may still be in the soil.
If you find bacterial canker on your cherry tree, cut off the sick branches, bag them up, and take them away from the tree. Do not put the bags in your compost pile. Photo credit: OrchardPeople. com.
Bacterial canker as a common cause of gummosis in cherry trees
There are many things that can hurt your cherry tree, but a bacterial disease called Pseudomonas syringae, which is also called bacterial canker, makes things worse. This pathogen affects other stone fruit trees as well like plums, apricots and peaches.
Other symptoms of bacterial canker include brown spots or holes on the leaves and the death of new shoots and young branches. Grow Fruit Trees That ThriveSign up for our newsletter and get this
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Cherry Gummosis – This Week in the Garden
FAQ
How do you treat gummosis on cherry trees?
Gummosis, characterized by sap oozing from cherry tree bark, is often a symptom of stress or injury, not a disease itself. Treating gummosis involves addressing the underlying cause, which could be mechanical damage, fungal infections like Cytospora canker, or environmental factors like overwatering. The most important things to do to control gummosis are to cut off infected branches, water and mulch trees properly, and protect the bark from winter damage.
How do you stop fruit trees from leaking sap?
To stop sap dripping from trees, address the underlying cause, which is typically honeydew-producing insect infestations. To control these pests, consider using insecticidal soaps, horticultural oils, or natural predators such as ladybugs.
Is cherry tree sap poisonous?
Yes, some parts of a cherry tree can be poisonous, including the leaves, twigs, and seeds.
What to do if a tree is leaking sap?
Prune Your Tree Cutting off small branches dripping sap may help stop sap from leaking. You want to make sure you prune during your tree’s dormant season or you may cause unnecessary stress, which could eventually kill your tree.
Why is my cherry tree sap oozing?
If the sap oozing from cherry trees is free of sawdust and more than a foot above the ground, you’re probably looking at canker disease. There are a few types of canker disease that cause sap oozing from cherry trees, and all of them result in sunken, dead material (or cankers) around the ooze.
Why is my Cherry Tree oozing so much?
Some sap leakage is normal for trees, but too much oozing is a sign of a bigger problem. It’s the tree’s desperate attempt to hide damage or disease. But too much sap loss saps the cherry tree’s vigor over time.
Why do fruit trees ooze sap?
A Fruit tree leaks sap for three main reasons: Most commonly peach, nectarine, plum or cherry trees ooze sap, but why? This phenomenon called “gummosis” is the tree’s response to stress. The cause of stress may be multi-faceted or result from singular, sinister pest and disease agents.
What causes sap oozing on a tree?
Environmental stress – Extreme weather, poor soil, insufficient water, and nutrient deficiencies stress the tree, leading to gummosis. Damage from lawn mowers, string trimmers, frost cracks, and other physical wounds can cause sap to leak out as the tree tries to heal.
Why is my cherry tree sap leaking?
The main cause of cherry tree sap leaking is a fungal disease known as “Black Knot.” This fungal disease, which is caused by a number of different species of fungi, damages the cherry tree’s bark and causes sap to leak. Additionally, it can also cause your cherry tree to be more susceptible to other diseases and pests.
How do I prevent cherry tree sap leaking?
Fortunately, there are a few ways you can protect and prevent cherry tree sap leaking. One way is to make sure that your cherry tree is adequately watered during the summer – when sap is actively running through the cherries. Having your tree well-watered helps protect the tree’s bark from extreme temperatures, fungal diseases, and pests.