Hi Folks,
I received a Santa Rosa plum about 4 years ago from an online nursery. Almost from the beginning I would see what looked like a golden brown ooze coming out from specific places in the trunk of the tree. The ooze would dry out and then turn into a solid mass almost hard as rock. To me it looked like just plain old tree sap coming out from places of injury in the cambium layer. I didn't think much of it. Once I use a razor to cut off a section of the trunk that had this sap and then painted over it with white latex paint. Eventually it healed over fine. The other day I was walking past this tree and I noticed some more of this sap looking material. I touched it and it was really hard. Incidentally most of my apricot trees show the same sap oozing from the upper branches. I thought well this is just the tree waking out of dormancy and pushing so much sap out to the branches that it likely burst through the cambium layer in places and then froze solid. Here is why I am concerned though. Recently we have had lots of rain come through. Almost two days worth of rain. And also the temps have been high and it has been humid and sticky. Today I walked past that Santa Rosa plum tree and I see that some of the material which I thought was sap was gone and in places it was starting to ooze out again. I touched it and it was soft like jelly not hard as it was before. I looked on the ground near the trunk and I saw some piece of the material that had cleft off from the trunk and fallen onto the ground. I grabbed a paper towel and wiped off the material on the trunk and picked up the material from the ground. Then put it into a plastic bag and sealed it. Then I tossed it into the garbage. I am worried that I might be looking at fireblight cankers on my plum tree instead of tree sap. I am new to pomme and stone fruit growing and I don't really have prior experience dealing with fireblight. I was hoping you might be able to help me diagnose what this thing is. I will attach pictures later if you think it helps but I can say that the tree does not look sick. There are no wilted branches and nothing seems to be dying. I pruned it earlier this winter and the tree is now putting out lots of new shoots from the main trunk as well as from the other branches. Given that there is no sign of the kind of burned damage you would expect to see with fireblight is it likely this could just be sap from the tree instead? I really don't want to uproot the tree but I will if I think it is a threat to the rest of the orchard.
Thanks.
Can someone please have a look at these pictures and give me some feedback? Is this fireblight or maybe a fungal bacteria? I can add that when I was sampling the ooze yesterday it did not have any kind of smell. I have heard that the fireblight ooze has a sweet smelling order that attracts insects. I didn't notice any but because I have no prior experience with fireblight I don't know if the odor is strong enough for humans to detect.
I went ahead and cut the infected material out of the bark, sprayed the wound with a copper based fungicide (liquicop) and then repainted over it with exterior white latex paint which also has anti-fungal properties. My guess is I am dealing with Cytospora Canker on my Santa Rosa plum tree. I have three other Santa Rosa plum trees and none of them exhibits this problem. So I know this is not normal for these fruit trees. If you guys think my diagnosis might be wrong please feel free to let me know. I am interested in thoughtful criticisms.
caseroj wrote "Can someone please have a look at these pictures and give me some feedback? Is this fireblight or maybe a fungal bacteria?"
I think you can rule out fireblight.
From what I've heard but not experienced, the fireblight looks like the effected branch ends have been subjected to fire; dried up, twisted and curled, blackened leaf and stems. I don't know where you are, but it's commonly thought that where I am located, PNW west of the Cascades, the fireblight has not yet been a problem. Apparently this is subject to change as the climate shifts.
Concurrently, stone fruits in this region are known to be subject to all sorts of splash-spread, damp springtime environs, bacterial maladies. Bacterial, viral, and fungal distinctions are out of my depth at this time
, but others on this forum who are studied and variously practiced, hopefully, will have some time to respond soon. Another recent thread "Thoughts on Peach Leaf Curl resistant varieties" brings up the term 'bacterial canker', which may be generically what you have named more specifically. I suppose there to be a litany of specific cultures.
It would probably be helpful to know where you are situated.
I am in East Central Florida zone 9b. So yes we do have high humidity in this area and this whole week it has been raining almost every day. Due to the El Nino event of 2014-2015 we had several years (only now has our weather pattern returned to normal) of drought. Almost no rain would fall and I had to water all my trees by hand. Maybe that's why I have not yet experienced significant problems with disease in my orchard yet. If you want to know what the weather was like exactly in my orchard you can check here
https://www.wunderground.com/p.....sh#history
That's the weather underground link to all the data associated with a personal weather station in my home orchard. It shows the levels or rain fall and temperatures as well as barometric pressure and wind speed/direction. After I cut out the infect material yesterday and painted over it the rains started up again. This morning I checked the wounds and I did seem some sap. This stuff was completely clear and colorless/odorless so I am convinced it was just sap from the wounds. I got the idea of cytospora canker from this video on youtube.
Admittedly my problems don't look that bad but then again my tree is much younger. My concern is that I see this stuff traveling closer to the root of the tree. Not sure if it will kill the tree once it reaches the roots but there is little I can do to prevent it now anyway.
Here is something interesting that I found just now
https://horticulturetalk.wordp.....ra-canker/
Some of the symptoms they describe for the cytospora canker sound similar to what I am seeing. I paint my trunks with white latex paint to prevent sun burn since I we have such a hot sunny summer. I do notice that the areas where the ooze emanates from is always raised above the rest of the bark. I have apples and other plums nearby this tree so maybe my habit of painting the trunk has saved them from infection. Unfortunately in the web site above they recommend pruning a fair amount behind the canker. If I do that at this stage I lose the tree because it is so close to the grafting union. I have been debating whether I should remove this tree for several years now. It's the fastest growing plum tree I have but it hasn't really produced any fruit. Only just this year did I get some flowers. I managed to pollinate one of them with pollen from another nearby plum tree and one fruit was set. Unfortunately, the tree itself pruned the fruit earlier this years about a month ago. So far I have not receive any fruit from this tree. I wonder if I should just cut my losses and tear it out. Break my heart to do it because I have invested so much time into the tree. The money lost is not what hurts me. It's the wasted time and effort that pains me the most.
I was looking through the trunk of the tree earlier today and found on additional lesion. This one does look very much like the cytospora canker referenced in the OSU video above. So I am now about 90% confident that is what I am dealing with. Now that I know I can pay more attention to this tree and monitor these cankers. I don't mind periodically removing them and cleaning things out if it means my Santa Rosa plum tree can survive and produce fruit someday!
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