Spots on apple tree leaves

Question: Hello!I live in Oxford, MI and I'm looking for help identifying the problem with my honeycrisp and pink last apple trees. I planted these in the spring of 2023. Early in the spring of this year I noticed damage to the lower bark (we have tree rings, so it's not from lawn mower, etc... But could be from critters) and shortly afterwards I noticed some spots on the leaves. It's been getting progressively worse. I've included pictures.What can I do to treat this? I'm really hoping to save these trees!

responder: Lindsay Brown  Replied August 07, 2024, 2:04 PM EDT
response: Hi Rachel,  There are multiple sources of damage here! Apple trees are uniquely difficult. They are excellent at getting attacked by all kinds of fungi, bacteria, and insect pests. Unfortunately, our disease control measures are designed to be proactive rather than reactive. General recommendation: Honeycrisp are notoriously sensitive. I would make sure you are applying plenty of nutrients and water to these trees throughout the season - especially calcium.  This fall, I would recommend removing any leaves from around the base of the trees when they fall. The leaves will harbor overwintering pathogens. Also this fall, apply a broadspectrum fungicide with copper or sulphur in it to the whole tree. Re-apply the fungicide in the spring prior to budbreak. Regular treatments of fungicides and insectides are needed to make sure no pests get at your trees. I will refer you to the resources below for details on those management decisions! I have apple integrated pest management resources attached here with information on how to manage these trees in the future. The Cornell Guide to Growing Fruit is a general approach to pest management and horticulture. The Apple IPM for Beginners guide is a nice intro to what can go wrong and when to treat for it. The organic guide is much more in depth, but if you are interested in growing organically it is a handy resource.

responder: The Question Asker Replied August 07, 2024, 4:02 PM EDT
response: Thank you for this information. I do have more questions:   You said to remove leaves and debris from the base of the trees. Should I be concerned about the wood mulch around the trees? Is there a better practice for weed control at the base of the tree? I usually add new mulch on top of the old in the spring. Should I be removing the old mulch entirely to reduce these pathogens?   Thanks,       On Wed, Aug 7, 2024, 2:04 PM Ask Extension <<personal data hidden>> wrote:

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responder: Lindsay Brown  Replied August 19, 2024, 8:30 AM EDT
response: Good morning Rachel,  Wood mulch is just fine here! The infected leaves and any fallen branches from the tree are primarily the potential problem here as they can harbor pathogens and help them overwinter in place.  Best,