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Watering apple and aspen tree #941828

Asked August 07, 2026, 3:59 PM EDT

Hello! We have an apple tree and an aspen tree on our property on the same irrigation line that don't seem to be doing well. 1. Apple tree - This is a pretty old tree. The diameter of the trunk is about 10". 3 of the branches of the apple tree have died and the leaves are curling. I'm not seeing any evidence of aphids. Photos attached. 2. Aspen tree - In the last month the leaves have started to turn brown. The leaves are not crispy. Photos attached. We have a TON of mulch under them, probably close to 18", and they are on drip emitters which we run every couple of weeks for 4hrs. I think we're overwatering them, but I would love your thoughts. Thank you! Emma

Deschutes County Oregon

Expert Response

Hi Emma,
Thank you for your question about your apple and aspen trees.

My first thought is that your mulch is quite deep at 18 inches. In general, mulch is recommended to be 3-4 inches deep. This includes any remaining mulch you may have added years before. Over mulching can create problems for the trees. Too much mulch can suffocate the roots, as the roots need oxygen for respiration. Deep mulch may create wet, moist soil; however, fungal diseases can develop in this situation.  I cannot determine what is causing the issues with your trees from your photos.

I am attaching some articles about mulching that you may find helpful. I recommend you call the Deschutes County OSU Extension office in Redmond at<personal data hidden> and ask to speak with Amy Jo Detweiler (oregonstate.edu). Amy Jo is our Community Horticulturist. She welcomes your garden questions and is a great resource. I am sure a conversation with Amy Jo will provide you with more information and helpful advice to assist you with your trees.

FS099: Problems With Over-Mulching Trees and Shrubs (Rutgers NJAES)

The Do’s and Don’ts of Mulching » Tree Care, Trees » HF&G

fact-sheet-watering-your-trees.pdf


Susan P., OSU Master Gardener Volunteer Replied August 10, 2026, 1:06 PM EDT

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