Gummosis (Whether induced) in Almond tree. - Ask Extension
Hello,
About an hour ago, I noticed good sized globules of tree sap under my almond tree. While searching, I found gummosis, and its symptoms.
W...
Knowledgebase
Gummosis (Whether induced) in Almond tree. #786750
Asked April 13, 2022, 5:34 PM EDT
Hello,
About an hour ago, I noticed good sized globules of tree sap under my almond tree. While searching, I found gummosis, and its symptoms.
While I did prune the tree in winter, the sap is not flowing from those cuts, but from the buds on established branches.
I have (in addition to the almond tree) a dwarf bing cherry tree, a pink lady apple tree and an anjou pear tree. None of these trees show any symptoms of stress or disease.
Also, I did treat all the trees in my backyard with fungicide prior to winter, and again before the buds broke in spring. The almond tree flowered on or about March 10th.
Any help or advice is greatly appreciated.
Lane County Oregon
Expert Response
Just got assigned this overdue question. Stone fruits (which include almonds) do have a tough time with the weather in the Willamette Valley. Cherries can do well, peaches are possible but there is a reason almonds are grown in southern CA - cold. Almonds flower early and can be hit with cold temps that can wipe out the crop or cause damage.
The flowers in your images all seem to be brown and necrotic. The ooze from these areas is a typical response of stone fruits to any kind of injury. The ooze has a very clear yellow color and that might be a good sign that it is just an injury response rather than an infection. (But that is not a hard and fast rule.) I have seen piles of ooze under peach trees that are other wise healthy. Here is some more info on gummosis: https://pnwhandbooks.org/plantdisease/host-disease/cherry-prunus-spp-gumming
Bacterial canker, as mentioned earlier, is likely on stone fruits. It is the number one establishment problem for all stone fruit throughout Oregon. The ooze can be much darker and somewhat cloudy. Here is some info on bacterial canker: https://pnwhandbooks.org/plantdisease/host-disease/cherry-prunus-spp-bacterial-canker
I would wait and watch what happens before doing too much. If the wood begins to die and shoots collapse then you can do some pruning of the affected branches. But they might recover just fine if not infected with the bacteria.
There are other issues that pome fruit get but not the ones discussed above. As for the fungicides, well, that depends on the active ingredient that you used. I would not expect them to be involved with this injury.
The flowers in your images all seem to be brown and necrotic. The ooze from these areas is a typical response of stone fruits to any kind of injury. The ooze has a very clear yellow color and that might be a good sign that it is just an injury response rather than an infection. (But that is not a hard and fast rule.) I have seen piles of ooze under peach trees that are other wise healthy. Here is some more info on gummosis: https://pnwhandbooks.org/plantdisease/host-disease/cherry-prunus-spp-gumming
Bacterial canker, as mentioned earlier, is likely on stone fruits. It is the number one establishment problem for all stone fruit throughout Oregon. The ooze can be much darker and somewhat cloudy. Here is some info on bacterial canker: https://pnwhandbooks.org/plantdisease/host-disease/cherry-prunus-spp-bacterial-canker
I would wait and watch what happens before doing too much. If the wood begins to die and shoots collapse then you can do some pruning of the affected branches. But they might recover just fine if not infected with the bacteria.
There are other issues that pome fruit get but not the ones discussed above. As for the fungicides, well, that depends on the active ingredient that you used. I would not expect them to be involved with this injury.
Hello my trusted friends at OSU Extension,
What can I do to rid myself of an apparent infestation? I've lost this years almonds to these little buggars.
Outside of professional pest control, is there a proven method to get rid of them?
I do have hummingbirds that take refuge in this tree on a daily basis, so I wouldn't want to go chemical until after first frost this coming fall/winter.
Any help would be appreciated.
Regards,
Jim Collins
Hi Jim, These are brown marmorated stink bug nymphs and yes they love almonds. We see the same in our late blooming almond trial plot. There really isn't a great management solution outside of insecticides, but for some crops exclusion netting can help prevent damage. Bagging apples for example can work well. That really isn't very practical for almonds but you could potentially net a whole tree. We also like kaolin clay as a deterrent for this insect, to homeowners it is marketed as "surround at home". It can be sprayed on the whole tree (turning it white). The bugs don't like it and it is not harmful to the tree, it actually helps the tree manage drought stress. Finally, I would be remiss not to mention that we are actively engaged in a biological control program against this insect. The egg parasitoid Trissolcus japonicus is becoming more widely established after it arrived in Oregon on its own and has been redistributed. It attacks the egg masses: https://catalog.extension.oregonstate.edu/em9164.
