Apple tree disease - Ask Extension
What is this brown spot disease on my apple tree? Does any spray work, like Monterey horticultural oil?
Knowledgebase
Apple tree disease #869402
Asked May 21, 2024, 9:10 AM EDT
What is this brown spot disease on my apple tree? Does any spray work, like Monterey horticultural oil?
Multnomah County Oregon
Expert Response
We need more information to offer a diagnosis and treatment option for your tree. Provide a photo of the lower leaf surface. Also, a photo from a distance of the whole tree. Describe the % of the tree that is damaged, and what the history of the leaf problem is in recent years and how the fruit crop has been. Did the flowering look healthy this spring? Have you treated the tree for this or any other pests or diseases this year or last?
I want to share a link for EC 631, our main publication for managing home orchard disease and pests.
I look forward to hearing back from you.
I want to share a link for EC 631, our main publication for managing home orchard disease and pests.
I look forward to hearing back from you.
This is the Gravenstein in question, pictured from an angle as it is up against the back fence. I'd say about 25% of the leaves are affected, and this is the first year it has flowered enough to set fruit ( the tree is at least 6 years old). I think I saw this brown spot in a previous year but I'm not sure. I spray my trees with Monterey horticultural oil every year, because we seem to get worms in the fruit and some sort of leaf curl- not sure if it's codling moth or apple maggot. Thanks for any info you may have.
On Wed, May 22, 2024 at 10:32 AM, Ask Extension<<personal data hidden>> wrote:
You may have several issues with the leaves of this apple tree. The first image shows a few necrotic spots. Not apple scab but might be something related to an unknown leaf spot described here: https://pnwhandbooks.org/plantdisease/host-disease/apple-malus-spp-necrotic-leaf-spot
The second and third images show necrotic leaf blotches that look a lot like leaf minor. An insect the burrows between the leaf epidermis. https://pnwhandbooks.org/insect/tree-fruit/apple/apple-leafminer
The third image does show apple scab on the fruit. https://pnwhandbooks.org/plantdisease/host-disease/apple-malus-spp-scab
The second and third images show necrotic leaf blotches that look a lot like leaf minor. An insect the burrows between the leaf epidermis. https://pnwhandbooks.org/insect/tree-fruit/apple/apple-leafminer
The third image does show apple scab on the fruit. https://pnwhandbooks.org/plantdisease/host-disease/apple-malus-spp-scab
