Plum Tree Infestation - Ask Extension
My plum tree got rocked by these little guys this year. Need oil seem to have stop them. They pretty much appeared over a few days that I was out of t...
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Plum Tree Infestation #804245
Asked August 02, 2022, 1:02 PM EDT
My plum tree got rocked by these little guys this year. Need oil seem to have stop them. They pretty much appeared over a few days that I was out of town. I’ve attached a photo. Could you please let me know the exact name of these things. Is there something I should do other than need oil? The tree was fruitless due to rain during pollination period. It was pruned in the spring and needs it again now. Should I wait until it’s winter dormant given that it’s had a lot of stress due to the bugs?
Thanks in advance
Gille Wilbanks
Multnomah County Oregon
Expert Response
Thanks for your question, Gille. I'm having difficulty seeing the insects on your tree's leaf, but it appears to be an infestation of aphids. This diagnostic page describes the various life cycles of aphids: https://pnwhandbooks.org/insect/tree-fruit/plum-prune/plum-prune-aphid You can wash them off with a strong stream of water, but, if that doesn't take care of the problem, the article recommends a variety of chemicals, including the active chemical in Neem oil. However, oils do nothing if not sprayed when the insect is an adult, rather than an egg. Please read the article to see when they should be applied, and follow label directions.
As for pruning, this is the wrong time. Your tree is already stressed, and hot temperatures and little water make it worse. I suggest you read the following guide to backyard orchards, from front to back, so you know the best practices for pruning and insects, among other issues: https://catalog.extension.oregonstate.edu/ec819
Good luck!
As for pruning, this is the wrong time. Your tree is already stressed, and hot temperatures and little water make it worse. I suggest you read the following guide to backyard orchards, from front to back, so you know the best practices for pruning and insects, among other issues: https://catalog.extension.oregonstate.edu/ec819
Good luck!
Thank you for getting back to me so quickly, I have a little concern in that what’s on my tree is completely white, no wings, very small body. I have not found any pictures of aphids that look like these. I have attached another photo. Hopefully it’ll be more clear. The ruler marks on the photo or a 16th of an inch.
I had some leaf curl but these don’t seem necessarily associated with those locations. In addition these are all located on tops of the leaves, none on the bottom.
Thanks again for your time,
Gille Wilbanks
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Gille: Sorry, but no photo was attached. This page has a list of the 19 insect pests of plum trees: https://pnwhandbooks.org/insect/crop-pests?combine=plum
I am sorry, but I simply cannot identify them. I suggest that you submit a sample to the OSU Insect ID Clinic: https://bpp.oregonstate.edu/plant-clinic/insect-id-clinic
Good luck!
Good luck!
OK. Thank you for your help! For my understanding, you are a Master Gardener, horticulturist, or ?
I will send an ID of these critters when I know.
Thanks again.
I am a Master Gardener volunteer, and have been on this panel for 7 years. Unfortunately, none of the 3 technologies I have access to can enlarge the photos with enough accuracy to provide a reliable ID. I can provide control suggestions, but only after an accurate identification is obtained.
Thanks for you time. It is appreciated. My wife and I just stumbled on some useful photo references. You were right. Looks like what is present is the “casting”, molted shells, of aphids. I have not seen any adult aphids. Just the white cast off skins. They look like some strange white spiders.
Well thanks, again. I will treat as aphids.
Good sleuthing!
