I have a semi-dwarf Italian prune plum tree, which I acquired as a bare-root sapling. Before it began producing fruit, it developed leaf curl. This sp...
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plum tree leaf curl #778155
Asked November 20, 2021, 1:42 PM EST
I have a semi-dwarf Italian prune plum tree, which I acquired as a bare-root sapling. Before it began producing fruit, it developed leaf curl. This spread over the course of 2-3 years, stunting the tree's growth and preventing any fruit production. Last year I sprayed the tree every two weeks from December to bloom with a solution of neem oil and dish detergent. The tree responded nicely. It had no leaf curl this year. It bloomed and produced about thirty plums (thirty more than the prior year). It grew 6-7 feet. It looked very healthy and happy.
My question is: should I spray again this year or can I assume the leaf curl is gone? The tree is so much bigger now, a spray job would be a lot harder.
Thank you!
Multnomah CountyOregon
Expert Response
I need to know what you mean by leaf curl. There is a disease name the same but there are insect problems with that symptom. I want to be sure of your diagnosis before I answer. You could send images or a web site that has a picture of what you saw....
I never took pictures of the problem on my tree. It affected the new growth on the tree and caused the leaves to tightly curl up and prevented the branch from growing. It started on one part of the tree and eventually spread to affect most of the growing ends of the branches. When I googled it, I encountered the problem of plum leaf curl which was described as being due to small aphids. Neem oil was a safe and recommended treatment. Usually there were quite a few small ants that would be attracted to the affected areas. I was told the ants themselves were probably not the problem, but were attracted to byproducts of the infestation. Here are a couple of websites I looked at.
OK, that helps a lot. Yes, the aphid issue and not disease. (The Neem oil woudl not have helped the disease but does for aphids.) The clincher are the ants which are attracted to the honey dew. In fact they are little farmers tending to the aphids and harvesting the honey dew.
So now its back to your original question about the sprays. I think you can back off on the number of applications. Have a look at our home orchard guide and it will help you with the amount of spraying you have to do: https://catalog.extension.oregonstate.edu/ec631
