Apple disease

Question: What is this apple disease? Can it be treated? how?

responder: Betsy, UVM Extension Master Gardener Volunteerwww.uvm.edu/extension/mastergardenerWe do not intend to endorse any products we mention or criticize products we do not mention.When we include a link to a resource that recommends a chemical, it is for informational purposesonly; the chemicals may not be registered for use in Vermont. Replied July 22, 2023, 8:15 PM EDT
response: Thank you for your question Joseph. This looks like one of the fungal apple diseases likely caused by the very wet weather we have been having. I am going add in a collaborator, Dr. Ann Hazelrigg, to address to get a specific ID on the disease. I believe this is apple scab, but she has the final word. A few questions that can help with treatment suggestions. How old is your apple tree and do you know what type of apple tree this is?  (Some apple tree varieties are more resistant to fungal infections). Are the branches and leaves affected as well? Are most of the apples affected at this point? Have you been pruning the tree regularly? Don't worry if you can't answer all of these questions.  To start treatment, you will want to remove affected fruit and leaves and discard them. Do not compost them. Clean your shears with 70% or higher percent alcohol between cuts and wash gardening gloves after use. Pick up any fallen leaves and discard them. You will want to try to increase air circulation for next season by pruning this winter when the tree is dormant. I am including some references on apple scab and apple tree pruning https://extension.umn.edu/plant-diseases/apple-scab https://www.uvm.edu/~orchard/fruit/treefruit/tf_horticulture/AppleHortBasics/Readings/trainprune.pdf

responder: The Question Asker Replied July 23, 2023, 6:19 PM EDT
response: It’s a Macintosh that I planted around 45 years ago . Pruned regularly, producing horizontal branch spread.

responder: Betsy, UVM Extension Master Gardener Volunteerwww.uvm.edu/extension/mastergardenerWe do not intend to endorse any products we mention or criticize products we do not mention.When we include a link to a resource that recommends a chemical, it is for informational purposesonly; the chemicals may not be registered for use in Vermont. Replied July 24, 2023, 9:43 AM EDT
response: Thanks you for the information Joseph. Dr. Hazelrigg confirmed that this is apple scab, a fungus. It's great that you prune regularly and that's probably why you have not had to deal with this before, but as you know, this has been a very unusual year.  At this point removing affected fruit and leaves and cleaning up fallen leaves so that the fungus is diminished in the soil is the best thing to do. A previously healthy tree can generally handle this disease. Please see the previously cited reference for an extensive discussion of apple scab prevention and treatment options. I hope this helps and best of luck. This has been a challenging gardening year in VT.

responder: The Question Asker Replied July 24, 2023, 9:48 AM EDT
response: Thank you so much for your quick response and advice.

responder: Betsy, UVM Extension Master Gardener Volunteerwww.uvm.edu/extension/mastergardenerWe do not intend to endorse any products we mention or criticize products we do not mention.When we include a link to a resource that recommends a chemical, it is for informational purposesonly; the chemicals may not be registered for use in Vermont. Replied July 24, 2023, 2:19 PM EDT
response: You are welcome Joseph. Dr. Hazelrigg also sent me the following info to help you: MacIntosh is a very susceptible variety to scab. Commercial orchardists typically spray fungicide 15-20 times/season to control this disease. If you are using the fruit for cider, this would not be so necessary but if you want blemish-free fruit, it takes a lot of time and effort and fungicides! The first factsheet from Minnesota has good advice if you are going to go the fungicide route. It is too late this year to rescue anything but you could start next year and bud break. I imagine the tree is pretty big which makes it hard to spray unless you have good equipment. Pruning and raking leaves will help decrease the amount of scab but it is likely the tree will have it to some extent every year.