Leucostoma persoonii and Leucostoma cincta
Gummosis refers to the oozing of sap or gum from a tree. This behavior is very common on stone fruits, including apricots, peaches, and plums.
You can look at gummosis as your tree’s cry for help in the face of any one of a number of problems.
The most common cause of gummosis is a fungus originally called Cytospora that is now called Leucostoma.
This fungus is opportunistic. That means that it infects easy targets like weakened trees. It requires both a wound and a tree that is stressed.
Pruning cuts are a major source of entry for this fungus. Sunscald and cold injury – and even deer rubs – can make your tree vulnerable to Cytospora infection.
Prevention is the best way to manage this condition.
What You Will Learn
Two Leucostoma Species Infect Fruit Trees
Two species of Leucostoma can be on the attack. L. persoonii is more likely to infect apricots, plums, peaches, nectarines and cherries grown at a low elevation. This species is more of a problem in warmer climates.
In contrast, L. cincta is more likely to attack apples and cherries in cooler areas, like orchards at high elevations.
Both species of fungus are widespread in the US and throughout British Columbia and Ontario, Canada as well. They have also been known to cause problems in South America, Europe, and Japan.
How to Diagnose Gummosis Due to Leucostoma Canker
Your tree will exhibit symptoms like dieback of the canopy and tree flagging. And it will produce a lot of gum. Think excessive.
The gum that Leucostoma fungi produce has a dark amber color. Scrape off the bark and look at the phloem underneath. It will be cinnamon brown.
Typically, the fungus grows during favorable times like the winter and spring. When the tree starts actively growing, it walls off the infection until it loses resistance again in the fall. You can see this pattern in the form of bands of lighter and darker colored tissue.
To distinguish Leucostoma canker from other causes of gummosis, you should look for its fruiting bodies – protrusions from the surface of the woody tissue that look like small black pimples.
These fruiting bodies can produce thousands of spores, and those of L. persoonii can travel up to 260 feet.
How to Prevent Gummosis
Cultural Controls
1. Optimal Fertilization and Care
Since the primary causal agent of apricot, peach, and plum gummosis attacks weakened trees, do your best to keep yours healthy with optimal mulching, watering, and nutrition.
You should consider fertilizing with nitrogen in the late winter or early spring. This will prevent your tree from producing growth that could be damaged by cold in the fall.
2. Prune Precisely and Remove Damaged Tissue
Be very careful when you prune. Make proper cuts and do not prune in wet weather. It is important to not leave stubs or flat cuts and to not make flush cuts.
Remove infected limbs and twigs by carefully pruning back to the healthy wood. You should do this during dry weather in the summer if possible, so the wound will heal as quickly as possible.
Sterilize your tools with Lysol wipes or 10% bleach between cuts.
It may not be possible to prune out all of the damage if the fungus has spread.
3. Protect from Sunscald
Protect the bark of your tree from sunscald during the winter. To do this, you have two choices.
One is to paint the trunk with half white latex paint and half water.
Your other choice is to apply white tree wrap from December to March.
4. Protect Against Rodents and Insects
Treat for rodents and insects, so they won’t create wounds in your tree. Some growers spray insecticides to keep borers from generating holes in the trees.
5. Drain Water from the Base of the Tree
You want to be sure to prevent injury to the crown from the cold. You can do this by draining water away from the tree’s base.
Chemical Controls
If you live in area where this pathogen is widespread, you should treat your tree with chemicals as a preventative measure.
Apply captan, thiophanate-methyl, or lime sulfur (Bordeaux mixture) in 50% latex or kaolin clay to freshly cut pruning wounds. Do not apply copper hydroxide, since this has been shown to be toxic to the trees.
If your trees are part of an organic program, lime sulfur is safe to use.
Monitor Your Tree Closely
Try and make sure that your tree is not stressed and doesn’t have any wounds on it.
Leucostoma canker is common in backyard trees, so be very careful when you prune them. You may want to apply a chemical treatment after pruning, so the fungus will not be able to enter through pruning wounds.
Keep an eye out for gummosis. If you see it, try and determine if it is due to fungal injury. If so, quickly prune out the damaged tissue before it spreads.
And if you do lose a tree to this fungus, please remove it. The fungus will continue to live on the dead tissue and will keep producing spores to infect other trees.
Have you waged war against gummosis in your garden or home orchard? If so, let us know how it went in the comments.
© Ask the Experts, LLC. ALL RIGHTS RESERVED. See our TOS for more details. Uncredited photos: Shutterstock.
About Helga George, PhD
One of Helga George’s greatest childhood joys was reading about rare and greenhouse plants that would not grow in Delaware. Now that she lives near Santa Barbara, California, she is delighted that many of these grow right outside! Fascinated by the childhood discovery that plants make chemicals to defend themselves, Helga embarked on further academic study and obtained two degrees, studying plant diseases as a plant pathology major. She holds a BS in agriculture from Cornell University, and an MS from the University of Massachusetts Amherst. Helga then returned to Cornell to obtain a PhD, studying one of the model systems of plant defense. She transitioned to full-time writing in 2009.
I was told my orange tree has this and to use Monterey garden phos., and he said “foot rot” also. Lost instructions- do I spray on root areas also?
Dear Doris,
Thank you so much for your question! I’m so sorry that your tree has gummosis. Yes – you should also spray the root areas. I hope your tree gets better!
I think my tree has gummosis. What should I do?
Hi Michelle, I’m sorry that your tree has gummosis. There may not be a lot that you can do after the fact. A key thing to do is to figure out whether your gummosis is due to a fungus or not. Look for protrusions on the wood that look like black pimples. If you see those, the gummosis is due to a fungal infection. Prune out the infected areas as soon as you can to prevent further spread. You should clean your pruning tools between cuts, so you don’t spread the infection. You can use either rubbing alcohol or bleach.
I have a fruit tree that has a huge opening in the trunk that I believe has gummosis. Once it is in the trunk, should the tree be removed or can it be treated?
There are a lot of causes for gummosis, so your first step is to determine whether it is due to a fungal infection or not. Look closely at the wood in the opening, and see if there are small protrusions that look like black pimples. If so, prune out the damaged area. Unfortunately, fungicides will not work at this point. You don’t need to remove the tree unless it dies. Hopefully it won’t come to that, but it will keep spreading the infection even after death.
Hi. I have a mango tree and not sure if it has gummosis. The leaves also have brown around them. Please look at the pictures and give me any suggestions… thanks
Hi Jessica, I’m sorry that your mango tree is showing such symptoms. Gummosis is a general term for conditions that cause those types of systems on the trunks, so I would say that your tree has gummosis. The fissure in the trunk looks like your tree has bacterial canker (Xanthomonas campestris). Are the cankers gummy? If so, spraying the whole tree with copper every 10 days should help. However, the symptoms on the leaves would not be caused by that disease. It looks like it could be a response to a heavy application of fertilizer. Have you fertilized your tree… Read more »
Hi, my peaches are all oozing a clear hard substance. The rest of the tree looks great. Any ideas?
Hi Rick, The most likely possibility is that an insect like a stink bug has pierced the flesh of the fruit. If that is the case, you will have to cut the blemish out of the fruit before you can eat it. A less likely possibility is that the fruit are sunburned. There isn’t much you can do in that case.
That looks like damage due to the oriental fruit moth to me
Hi Kathy, Thank you so much for sharing that information with us! I will do some research on the oriental fruit moth.
I don’t doubt the stink bugs but it’s also caused by a white Chinese moth. My poor beautiful peach tree is now dying from gummosis! I’m afraid it will has to be cut down. Probably got it from when it was pruned last fall. Maybe from the pruning equipment or got in there in the wounds. Those moths are crazy killers, can’t get rid of them.
Hi Ashley, I’m so sorry to hear that your peach tree is dying! Gummosis is a cry for help for many different problems. I just mentioned stink bugs, because they are so common. Do you have any photos of the horrible moths?
My peaches have this coming out of them. What can I do to prevent this from happening next year?
Hi Stephanie, Do you mean your peach fruit, or the tree? It’s hard to advise you without knowing exactly what is causing the gummosis. It’s your tree’s cry for help, so it could be due to any one of a number of factors. If you have sunken dark tissue on the stems, it is probably the fungus Leucostoma, which the article discusses. However, it can also be due to mechanical damage (hitting it with a mower or weed whacker), herbicide damage, insect infestations, certain viruses, winter damage, or environmental stress. Is there sawdust in the gum? That would suggest a… Read more »
After researching on the web, I believe my mango tree has gummosis. Any advice that you can give to help me bring this tree back to a healthy state would be much appreciated.
Hi Gabriel, Unfortunately, you are correct. Gummosis can indicate any one of a number of problems, but in your mango’s case, I think it is due to bacterial canker (caused by Xanthomonas campestris). You should prune out any infected twigs, although I don’t know how feasible that is. Also spray with copper when the weather is wet to help keep the infection from spreading.
THANK YOU!!!
Please advise on “spray with copper,” not sure what you mean by that.
Also, I read that I should sterilize a sharp knife and cut 1 inch around cracks and peel off the bark to allow the healthy wood trunk to heal itself.
Is there a spray to hook up to a hose, like from Home Depot, that would help with the first picture, what looks like fungus on the leaves and fruit branch portions?
Thanks again…
Hi Gabriel, That makes sense to cut around the cracks and peel off the bark. Sorry I was not more clear about the copper. Many companies make sprayable forms of copper to treat bacterial and fungal diseases. Here is a similar product that you can hook up to your hose to spray. It sounds like you are on the right track to cure your tree, and I hope that you are able to do so.
Do you think my peach tree has gummosis? What can I do?
Hi Neha, It’s difficult to tell from the pictures, but I believe that you are right. Gummosis can be caused by many factors, so what you should do depends on what is causing the disorder. One common reason is a fungus that infects through pruning wounds. Look closely at the bark and see if there are structures that look like small black pimples. If there are, that means your tree is infected. You should carefully prune out the damaged tissue to the healthy wood and make sure to sterilize your pruning shears as you go. You can use bleach, or… Read more »
Around 30% of my peach tree leaves started curling with bulges, some yellow leaves, and of course sap leaking from the stems. I’m more than positive this is Gummosis from fungi but in your expert opinion do you think the curling is a byproduct from the Gummosis since it’s also fungi based or is it two different types of fungi causing both Gummosis AND peach tree curling? Is it also too late for any meaningful preventive measures? Just today I have started pruning but I have little hope it’ll prove effective.
Hi Abe, I’m so sorry to hear that your peach tree is exhibiting symptoms. Do the curled leaves turn crazy colors? There is a very common disease called peach curl that doesn’t cause the tree to leak sap. I am wondering if you might have a different disease than the leaf curl one caused by Taphrina. If you do have the peach leaf curl disease and leaking sap, I would say that you have two separate problems. I would suggest that you get a professional diagnosis to figure out exactly what is going on. Do you have an agricultural university… Read more »
Is this gummosis? i just recently noticed this on my lemon tree and some branches have died already and I had to cut them off. I was planning to spray Dithane contact fungicide and was wondering if it could cure them, but afraid to spray directly on fruits as it might affect them too. thanks!
Hi Gaia, Yes. It looks like gummosis. However, a number of factors can cause that, including fungi, insects, and even physiological disorders. I would hold off on applying the fungicide for now until you can get a diagnosis for the problem. Even if it is due to a fungus, not every fungicide works on every fungal pathogen. One candidate is root rot caused by Phytophthora. This water mold rots the root system, so the rest of the tree suffers. Carefully dig near the crown of the plant and see if the fine roots are rotten or healthy and white inside.… Read more »
Hi,
Last year I planted bare root North Star cherry. This spring it started leaking sap in five sap mounds on the trunk, starting about four feet above the ground .The sap oozing from cherry tree is free of sawdust.
Is it harmful for the tree? What to do? Thank you in advance, Milla
Hi Milla, I am so sorry that your cherry trees are exuding so much sap! It’s good that it is free of sawdust, but it could still indicate a problem. So many factors can cause gummosis that I can’t diagnose it very effectively. It is a huge help that you provided pictures. The plants look so healthy otherwise! If you look at the stem, are there any sunken parts under the gum? That could indicate a fungal infection. Since I can’t say for sure, I would suggest that you bring in an arborist, or someone else who is specialized at… Read more »
My prunus also appears to have gummosis, and what I haven’t found addressed anywhere is how to deal with it on a tree that is very very young — no more than 1/4 inch caliper, planted just last fall. I couldn’t possibly remove much without killing the tree entirely. Is the tree lost? Any treatment possible? Thank you!
Hi Amy, I’m so sorry about your tree. That is definitely gummosis, but it can have a large number of causes. Aggressive pruning is designed to control the fungi that cause cankers, but it doesn’t look like your tree is infected with them. Other causes can include insect damage, mechanical damage, certain viruses, winter damage, adverse growing sites, and herbicide damage. Borers often attack stone fruits, but if that were the case, there would be pieces of sawdust and little brown spots of excrement mixed in with the gum. I can’t see from the picture. Are either of those present?… Read more »
I do not see evidence of borers. Would you advise not to apply copper until I’m sure of the issue? Appreciate your help, and I’ll plan to call the extension service today.
Hi Amy, I am so glad that you will be speaking with the extension service. I am highly curious about what advice they will give you. I would wait on the copper until you have a better idea of what the cause is. It can be toxic.
I will let you know! Thank you.
Hi Helga I am wondering if my flowering peach has gummosis. Do you think there is any way I can save it? It appears to be on the majority of this front side and I don’t think it would be possible to prune it away due to the extent. I am wondering if I can try and build the tree health to help.. It looks very healthy during summer (it is currently winter where I am) however, I noticed during summer gone that this side had less growth. I have never pruned my tree, I am thinking the damage… Read more »
Hi Lou, I’m so sorry about your tree. To be honest, I’m not sure if it has gummosis. The gum is typically amber-colored. You are right that mowers can cause gummosis. The drastic pruning is only if your tree is infected with the fungal canker. I would suggest that you consult an arborist in your area to get a definitive diagnosis. Another option is your county extension agent. Here is a link to find out who to contact in your area: https://offices.sc.egov.usda.gov/locator/app. I hope that he or she can help you. If you have time, please keep us posted as… Read more »
Can my cherry tree be saved or should I cut it down and re-plant? I planted it in fall 2009 and it has been a productive tree. A few years ago, it started leaking a little sap and now it has multiple sites. My fault for not doing something sooner. The open/oozing site in photo is on the south side of the trunk toward the bottom. Pictures attached. Used to be a small branch or two looked dead. Now more branches are leafless. 😟
Hi Paula, Your poor tree! It looks like it does have an infection with the Leucostoma fungus that causes cankers. Normally, the advice is to prune out the infected areas, but that looks really difficult from the one picture that shows it at the base of so many branches. I hate to make such an important decision on the basis of the pictures without seeing the tree. Would it be feasible to bring in an arborist to look at it? Another option could be to contact your local county extension person, who would know better about what is going on… Read more »
Thank you for your reply, Helga. I reached out to the University of MN Extension Master Gardener program and that person thought it might be gummosis (sent the same pics) and suggested sending in a sample to the university lab for diagnosis to be sure. Also, she didn’t think the tree could be saved. I’ll see if there is a local arborist… Again, thanks!
Hi Paula, Thank you so much for letting us know about the upcoming diagnosis! I am very sorry that they think that your tree cannot be saved.
Hi, I saw this blog and found it useful for this problem. I have two grafts with gummosis, unfortunately, today I killed the orange tree because of this disease. The other foot, of tangerine, is infected, it has a more or less thick trunk, it is still new. I haven’t decided if I should get rid of it too, since small breaks in the trunk are spewing gum, and around the bark it is brown in color. It is close to the root. Is there a method to save the foot I love so much? I’m sad about it, I’ve… Read more »
Hi Vitória, I’m so sorry that you had to kill your orange tree. I also hope that you can save the tangerine. Could you possibly post pictures? Are you sure that it is infected with Leucostoma fungus? Is that what you mean by brown on the stem? You could try pruning the infected tissue out to save the tree. The article has instructions on how to do that. However, many things can cause gummosis, and not all of them are contagious – damage from mowers or weed-whackers, herbicide damage, cold damage, and environmental stresses come to mind. Insects, especially borers,… Read more »
Hi
I have gummosis on fruits of peach not on trees.
What I have to spray in fungicide?
Hi Ijaz, I’m so sorry to hear that. Many things, including insect infestations, can cause peaches to exude gum. I think you need to identify the source of the problem before you decide on using a fungicide. I would strongly suggest that you contact your local county extension agent to see if he or she can diagnose the problem and then advise you on the best treatment. The link to find the appropriate person is listed in my reply to Lou above. Another option might be a local ag school if there is one nearby. Please keep us posted as… Read more »
Hi , not sure if this thread is active still but is there anything I can do to stop mine from oozing?
Here’s another pic
Hi Aron, Yes! We are still answering questions. Your question is an excellent one that is very difficult to answer. Trees produce gum as a response to stress. You would have to address the underlying problem to get them to stop. I’m not positive, but it looks like your tree might have Leucostoma canker, which can infect at sites that have been pruned. The article discusses how to manage it. I would suggest that you get a professional diagnosis to make sure, so you know how to treat it. A local ag university or your local extension agent would be… Read more »
Just noticed this today and I see sap oozing from a few places in my nectarine tree, including the trunk. It seems to have just started. Is there anything I can do to help the tree? We love our tree! Thank you!
Hi Vijay, I’m so sorry about your tree. It is definitely gummosis, but that can be caused by a number of different factors. It is your tree’s cry for help. The problem is figuring out exactly what is wrong. Injuries from mowers or weed whackers can cause it, but that looks too high up on the tree for that to be the case. I can’t tell from the picture. Had the tree been pruned there? If so, it could be an infection by the fungus that causes Leucostoma canker that is discussed in the article. I would suggest you bring… Read more »
Hello! I think my Cherry tree has gummosis as well! Do you think I can still save him!? Help!! What should I do with my tree? What should I buy to make him better please!!?? Thank you!
Hi Bianca, I am so sorry that your cherry tree has gummosis. Unfortunately, a number of different things can cause this condition. They range from fungal infections and infestation by borers to herbicide damage, mechanical injury, and various environmental stresses. It’s difficult for me to figure out what is going on based on that one symptom. I would suggest that you contact your local horticulturalist and ask their advice. Another option is your county extension person. The link to contact them is in my reply to Lou’s question. I am highly curious and would love to hear back from you… Read more »
Hi Helga, I would like to start by thanking you for helping so many people with their problems. I can see that unfortunately, I’m not alone here. Please see photos attached of my cherry, peach and nectarine. They are in raised beds above clay but I fear they have been overwatered this winter here in Tasmania, Australia. Possibly waterlogged for several months. It has been cold and wet for months where they are growing, with possible exposure to multiple frosts. Last winter I didn’t water the trees at all and some of the soil got very dry and crusty. This… Read more »
Hi Craig, Thank you so much for your kind words! I’m so sorry that your weather has been so conducive to diseases on your fruit trees! You said you were spraying Burgundy. Could you have meant Bordeaux? It can be difficult to diagnose cankers from pictures, but species of the fungi Leucostoma (formerly Cytospora) are the major sources of cankers on stone fruit trees. Apparently, fungicides do not always control the disease, and it is necessary to ruthlessly prune the cankers out. Here is a PDF from Pennsylvania State University that gives a lot of detail on exactly how to… Read more »
Thank you so much Helga! That Pennsylvania State University article was very informative. I will attempt surgery to remove the cankers as soon as we have a forecast of dry weather. This could be quite a wait! I noticed the cankers were oozing a lot of gum today after we have just had three days of rain. I had taken some scion wood and stored in the fridge for my father to graft onto his nectarine. I’m guessing this is a bad idea as it may transfer the disease to his orchard. The scion wood appears healthy, but I guess… Read more »
Hi Craig, I am delighted that the PDF was helpful. Thank you so much for letting us know! I think it might be okay to graft them. This fungus tends to invade where there are wounds on the tree, and I think a healthy tree could resist infection. I can’t say for sure, though. I think you should seek the advice of a professional arborist in your area. I was going to lead you to the USDA, but fortunately I remembered that you are in Australia! It seems as if each of your states offers agricultural advice, and I would… Read more »
I want to know how to control gummosis diseases in stone fruit
Did ya read the article? That’s what it’s about.
Good article, thanks. If it is the fungus it will probably kill my appricot tree, as I noticed gummosis all around the trunk 🙁
Hi Volodymyr,
Thanks so much for your comment, although I am horrified to see the picture of the trunk of your poor tree.
It’s difficult to diagnose from pictures, so let’s hope it’s a response to an environmental insult and not the fungus. Are there black structures on the trunk that look like pimples? Those are diagnostic for the fungus.
Please keep us posted!
Hi, i see that my peach tree is presenting the symptoms of gummosis but I can’t tell if it is caused by fungus or not. I don’t see any black pimples as you said. But the tree is dying at an alarming rate (more than half has died in just one month). One of the arborists I spoke to said it might be fungus and that it could spread to the other trees in our yard (Mulberry and Italian Cyprus). Could that be true? (they also mentioned that it could be nearby Oleander poisoning the roots which I have read… Read more »
Hi Jessica, Your poor tree! It’s hard to diagnose those kind of symptoms from a distance. The gummosis could be a side effect from a systemic infection by a fungus. There are a couple things that could be going on. There is a dreadful wilt called Verticillium that affects many trees and shrubs. Here is an article about it from Iowa State U. Another thing could be one of the fungi (or a nasty water mold) that can cause root rot in trees. We have an article on the different kinds with some tips to tell them apart. Some of… Read more »
Good evening Doctor, it was with great dismay that I discovered Gum and separating bark at the bottom of my orange tree, I know that a diagnosis from a couple of pictures is difficult but if you do not mind, would you please look at these and see what you think what the cause might be? Also, how to treat?
Hi Juan, Thanks for providing pictures! I’m very concerned about the white masses on your tree. They look like the fungus Armillaria (the honey mushroom fungus). It’s a very common pathogen in the soil and is usually fatal. However, there are several things to look for to figure out if it is this disease. We have an article on Armillaria in apple trees, but the basic symptoms are common between different types of hosts. I would look for the classic rhizomorphs in the ground. The article has a picture of them. If you caught it early, there is one thing… Read more »
Hi Helga – thanks for putting together such a useful blog! I recently moved into a new house in Oregon with a very sad cherry tree in back. I noticed sections where it looks like the previous owners may have extensively pruned which now have various knobs of new growth surrounded by amber and clear gummosis. The tree is really not growing well and I can’t even identify any non-affected sections! The worst gummosis is around the trunk and most of the leaves are full of holes. Do these look like cankers to you? I’d like to try something but… Read more »
Hi Carolyn, Thank you so much for your compliments on the site! It’s a team of writers and editors. I am so sorry to see the pictures of your poor tree. I don’t think the gravel would hurt the drainage, and I suspect that whatever insect is eating the leaves is a separate issue than what is causing the tree to decline. It’s hard to see in the pictures, but they do look like cankers. However, the canker and gummosis can be due to diseases other than the one discussed in this article. I’m going to refer you to another… Read more »